Merge #90

90: turn macros into attributes r=adamgreig a=japaric

This is a PoC implementation of RFC #82. Assuming that we are OK with this implementation we should
add some compile fail tests (e.g. using a function with the wrong signature as the entry point)
before landing this.

Look at the diff of the examples to get an overview of the changes.

cc @rust-embedded/cortex-m

Co-authored-by: Jorge Aparicio <jorge@japaric.io>

45 files changed, 1205 insertions, 319 deletions

diff --git a/cortex-m-rt/.gitignore b/cortex-m-rt/.gitignore
index c71d6db..d8748d6 100644
--- a/cortex-m-rt/.gitignore
+++ b/cortex-m-rt/.gitignore
@@ -1,4 +1,5 @@
 **/*.rs.bk
+.#*
 Cargo.lock
 bin/*.after
 bin/*.before
diff --git a/cortex-m-rt/.travis.yml b/cortex-m-rt/.travis.yml
index caa29ef..fd45f63 100644
--- a/cortex-m-rt/.travis.yml
+++ b/cortex-m-rt/.travis.yml
@@ -3,24 +3,29 @@ language: rust
 matrix:
   include:
     - env: TARGET=x86_64-unknown-linux-gnu
-      rust: stable
-      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
-
-    - env: TARGET=thumbv6m-none-eabi
-      rust: stable
-      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
-
-    - env: TARGET=thumbv7m-none-eabi
-      rust: stable
-      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
-
-    - env: TARGET=thumbv7em-none-eabi
-      rust: stable
+      # TODO switch to 1.30-beta
+      rust: nightly
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
-    - env: TARGET=thumbv7em-none-eabihf
-      rust: stable
-      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+      # TODO enable when 1.30-beta is out
+    # - env: TARGET=thumbv6m-none-eabi
+    #   rust: beta
+    #   if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
+      # TODO enable when 1.30-beta is out
+    # - env: TARGET=thumbv7m-none-eabi
+    #   rust: beta
+    #   if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
+      # TODO enable when 1.30-beta is out
+    # - env: TARGET=thumbv7em-none-eabi
+    #   rust: beta
+    #   if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
+      # TODO enable when 1.30-beta is out
+    # - env: TARGET=thumbv7em-none-eabihf
+    #   rust: beta
+    #   if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv6m-none-eabi
       rust: nightly
diff --git a/cortex-m-rt/Cargo.toml b/cortex-m-rt/Cargo.toml
index 0dfbaf7..9cf2c14 100644
--- a/cortex-m-rt/Cargo.toml
+++ b/cortex-m-rt/Cargo.toml
@@ -12,11 +12,15 @@ version = "0.5.3"
 
 [dependencies]
 r0 = "0.2.1"
+cortex-m-rt-macros = { path = "macros", version = "0.1.0" }
 
 [dev-dependencies]
-panic-semihosting = "0.3.0"
-panic-abort = "0.2.0"
 cortex-m = "0.5.4"
+panic-abort = "0.3.0"
+panic-semihosting = "0.4.0"
+
+[target.'cfg(not(target_os = "none"))'.dev-dependencies]
+compiletest_rs = "0.3.14"
 
 [features]
 device = []
diff --git a/cortex-m-rt/ci/script.sh b/cortex-m-rt/ci/script.sh
index 7d1cc67..cecb975 100644
--- a/cortex-m-rt/ci/script.sh
+++ b/cortex-m-rt/ci/script.sh
@@ -5,18 +5,31 @@ main() {
 
     cargo check --target $TARGET --features device
 
+    if [ $TARGET = x86_64-unknown-linux-gnu ]; then
+        ( cd macros && cargo check && cargo test )
+
+        cargo test --test compiletest
+    fi
+
     local examples=(
         alignment
-        minimal
+        divergent-default-handler
+        divergent-exception
+        entry-static
         main
+        minimal
         override-exception
         pre_init
         state
+        unsafe-default-handler
+        unsafe-hard-fault
+        unsafe-entry
+        unsafe-exception
     )
     local fail_examples=(
         data_overflow
     )
-    if [ $TRAVIS_RUST_VERSION = nightly ]; then
+    if [ $TARGET != x86_64-unknown-linux-gnu ]; then
         # linking with GNU LD
         for ex in "${examples[@]}"; do
             cargo rustc --target $TARGET --example $ex -- \
@@ -48,29 +61,23 @@ main() {
         # linking with rustc's LLD
         for ex in "${examples[@]}"; do
             cargo rustc --target $TARGET --example $ex -- \
-                  -C linker=rust-lld \
                   -C link-arg=-Tlink.x
 
             cargo rustc --target $TARGET --example $ex --release -- \
-                  -C linker=rust-lld \
                   -C link-arg=-Tlink.x
         done
         for ex in "${fail_examples[@]}"; do
             ! cargo rustc --target $TARGET --example $ex -- \
-                  -C linker=rust-lld \
                   -C link-arg=-Tlink.x
 
             ! cargo rustc --target $TARGET --example $ex --release -- \
-                  -C linker=rust-lld \
                   -C link-arg=-Tlink.x
         done
 
         cargo rustc --target $TARGET --example device --features device -- \
-              -C linker=rust-lld \
               -C link-arg=-Tlink.x
 
         cargo rustc --target $TARGET --example device --features device --release -- \
-              -C linker=rust-lld \
               -C link-arg=-Tlink.x
     fi
 
diff --git a/cortex-m-rt/examples/alignment.rs b/cortex-m-rt/examples/alignment.rs
index 5635851..25d755d 100644
--- a/cortex-m-rt/examples/alignment.rs
+++ b/cortex-m-rt/examples/alignment.rs
@@ -4,13 +4,12 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry)]
 extern crate cortex_m_rt as rt;
 extern crate panic_abort;
 
 use core::ptr;
 
-entry!(main);
+use rt::entry;
 
 static mut BSS1: u16 = 0;
 static mut BSS2: u8 = 0;
@@ -19,6 +18,7 @@ static mut DATA2: u16 = 1;
 static RODATA1: &[u8; 3] = b"012";
 static RODATA2: &[u8; 2] = b"34";
 
+#[entry]
 fn main() -> ! {
     unsafe {
         let _bss1 = ptr::read_volatile(&BSS1);
diff --git a/cortex-m-rt/examples/data_overflow.rs b/cortex-m-rt/examples/data_overflow.rs
index 396f1c8..ceec18b 100644
--- a/cortex-m-rt/examples/data_overflow.rs
+++ b/cortex-m-rt/examples/data_overflow.rs
@@ -5,13 +5,12 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry)]
 extern crate cortex_m_rt as rt;
 extern crate panic_abort;
 
 use core::ptr;
 
-entry!(main);
+use rt::entry;
 
 // This large static array uses most of .rodata
 static RODATA: [u8; 48*1024] = [1u8; 48*1024];
@@ -20,6 +19,7 @@ static RODATA: [u8; 48*1024] = [1u8; 48*1024];
 // without also overflowing RAM.
 static mut DATA: [u8; 16*1024] = [1u8; 16*1024];
 
+#[entry]
 fn main() -> ! {
     unsafe {
         let _bigdata = ptr::read_volatile(&RODATA as *const u8);
diff --git a/cortex-m-rt/examples/device.rs b/cortex-m-rt/examples/device.rs
index 4395db2..950a564 100644
--- a/cortex-m-rt/examples/device.rs
+++ b/cortex-m-rt/examples/device.rs
@@ -5,13 +5,12 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry)]
 extern crate cortex_m_rt as rt;
 extern crate panic_semihosting;
 
-// the program entry point
-entry!(main);
+use rt::entry;
 
+#[entry]
 fn main() -> ! {
     loop {}
 }
diff --git a/cortex-m-rt/examples/divergent-default-handler.rs b/cortex-m-rt/examples/divergent-default-handler.rs
new file mode 100644
index 0000000..cbb8bb1
--- /dev/null
+++ b/cortex-m-rt/examples/divergent-default-handler.rs
@@ -0,0 +1,19 @@
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+fn DefaultHandler(_irqn: i16) -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/examples/divergent-exception.rs b/cortex-m-rt/examples/divergent-exception.rs
new file mode 100644
index 0000000..9998884
--- /dev/null
+++ b/cortex-m-rt/examples/divergent-exception.rs
@@ -0,0 +1,18 @@
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+fn SysTick() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/examples/entry-static.rs b/cortex-m-rt/examples/entry-static.rs
new file mode 100644
index 0000000..1b2e118
--- /dev/null
+++ b/cortex-m-rt/examples/entry-static.rs
@@ -0,0 +1,20 @@
+//! `static mut` variables local to the entry point are safe to use
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt as rt;
+extern crate panic_semihosting;
+
+use rt::entry;
+
+#[entry]
+fn main() -> ! {
+    static mut COUNT: u32 = 0;
+
+    loop {
+        *COUNT += 1;
+    }
+}
diff --git a/cortex-m-rt/examples/minimal.rs b/cortex-m-rt/examples/minimal.rs
index a036046..6f60180 100644
--- a/cortex-m-rt/examples/minimal.rs
+++ b/cortex-m-rt/examples/minimal.rs
@@ -5,13 +5,13 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry)]
 extern crate cortex_m_rt as rt;
 extern crate panic_semihosting;
 
-// the program entry point
-entry!(main);
+use rt::entry;
 
+// the program entry point
+#[entry]
 fn main() -> ! {
     loop {}
 }
diff --git a/cortex-m-rt/examples/override-exception.rs b/cortex-m-rt/examples/override-exception.rs
index 2f100a2..3e0af25 100644
--- a/cortex-m-rt/examples/override-exception.rs
+++ b/cortex-m-rt/examples/override-exception.rs
@@ -6,29 +6,24 @@
 #![no_std]
 
 extern crate cortex_m;
-#[macro_use(entry, exception)]
 extern crate cortex_m_rt as rt;
 extern crate panic_semihosting;
 
 use cortex_m::asm;
-use rt::ExceptionFrame;
-
-// the program entry point
-entry!(main);
+use rt::{entry, exception, ExceptionFrame};
 
+#[entry]
 fn main() -> ! {
     loop {}
 }
 
-exception!(*, default_handler);
-
-fn default_handler(_irqn: i16) {
+#[exception]
+fn DefaultHandler(_irqn: i16) {
     asm::bkpt();
 }
 
-exception!(HardFault, hard_fault);
-
-fn hard_fault(_ef: &ExceptionFrame) -> ! {
+#[exception]
+fn HardFault(_ef: &ExceptionFrame) -> ! {
     asm::bkpt();
 
     loop {}
diff --git a/cortex-m-rt/examples/pre_init.rs b/cortex-m-rt/examples/pre_init.rs
index 7258936..00e2f2c 100644
--- a/cortex-m-rt/examples/pre_init.rs
+++ b/cortex-m-rt/examples/pre_init.rs
@@ -4,19 +4,17 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry, pre_init)]
 extern crate cortex_m_rt as rt;
 extern crate panic_semihosting;
 
-pre_init!(disable_watchdog);
+use rt::{entry, pre_init};
 
+#[pre_init]
 unsafe fn disable_watchdog() {
     // Do what you need to disable the watchdog.
 }
 
-// the program entry point
-entry!(main);
-
+#[entry]
 fn main() -> ! {
     loop {}
 }
diff --git a/cortex-m-rt/examples/state.rs b/cortex-m-rt/examples/state.rs
index dbacdaf..573914f 100644
--- a/cortex-m-rt/examples/state.rs
+++ b/cortex-m-rt/examples/state.rs
@@ -5,20 +5,20 @@
 #![no_main]
 #![no_std]
 
-#[macro_use(entry, exception)]
 extern crate cortex_m_rt as rt;
 extern crate panic_semihosting;
 
-// the program entry point
-entry!(main);
+use rt::{entry, exception};
 
+#[entry]
 fn main() -> ! {
     loop {}
 }
 
 // exception handler with state
-exception!(SysTick, sys_tick, state: u32 = 0);
+#[exception]
+fn SysTick() {
+    static mut STATE: u32 = 0;
 
-fn sys_tick(state: &mut u32) {
-    *state += 1;
+    *STATE += 1;
 }
diff --git a/cortex-m-rt/examples/unsafe-default-handler.rs b/cortex-m-rt/examples/unsafe-default-handler.rs
new file mode 100644
index 0000000..48bd31e
--- /dev/null
+++ b/cortex-m-rt/examples/unsafe-default-handler.rs
@@ -0,0 +1,16 @@
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+unsafe fn DefaultHandler(_irqn: i16) {}
diff --git a/cortex-m-rt/examples/unsafe-entry.rs b/cortex-m-rt/examples/unsafe-entry.rs
new file mode 100644
index 0000000..feb6f44
--- /dev/null
+++ b/cortex-m-rt/examples/unsafe-entry.rs
@@ -0,0 +1,13 @@
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry]
+unsafe fn foo() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/examples/unsafe-exception.rs b/cortex-m-rt/examples/unsafe-exception.rs
new file mode 100644
index 0000000..d67f06f
--- /dev/null
+++ b/cortex-m-rt/examples/unsafe-exception.rs
@@ -0,0 +1,16 @@
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+unsafe fn SysTick() {}
diff --git a/cortex-m-rt/examples/unsafe-hard-fault.rs b/cortex-m-rt/examples/unsafe-hard-fault.rs
new file mode 100644
index 0000000..b091d47
--- /dev/null
+++ b/cortex-m-rt/examples/unsafe-hard-fault.rs
@@ -0,0 +1,18 @@
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+unsafe fn HardFault(_ef: &ExceptionFrame) -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/macros/Cargo.toml b/cortex-m-rt/macros/Cargo.toml
new file mode 100644
index 0000000..d0644ee
--- /dev/null
+++ b/cortex-m-rt/macros/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "cortex-m-rt-macros"
+version = "0.1.0"
+authors = ["Jorge Aparicio <jorge@japaric.io>"]
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote = "0.6.6"
+rand = "0.5.5"
+proc-macro2 = "0.4.15"
+
+[dependencies.syn]
+features = ["extra-traits", "full"]
+version = "0.14.8"
+
+[dev-dependencies]
+cortex-m-rt = { path = ".." }
diff --git a/cortex-m-rt/macros/src/lib.rs b/cortex-m-rt/macros/src/lib.rs
new file mode 100644
index 0000000..bd34b04
--- /dev/null
+++ b/cortex-m-rt/macros/src/lib.rs
@@ -0,0 +1,534 @@
+#![deny(warnings)]
+
+extern crate proc_macro;
+extern crate rand;
+#[macro_use]
+extern crate quote;
+extern crate proc_macro2;
+extern crate syn;
+
+use proc_macro2::Span;
+use rand::Rng;
+use syn::{FnArg, Ident, Item, ItemFn, ItemStatic, ReturnType, Stmt, Type, Visibility};
+
+use proc_macro::TokenStream;
+
+/// Attribute to declare the entry point of the program
+///
+/// **IMPORTANT**: This attribute must be used once in the dependency graph and must be used on a
+/// reachable item (i.e. there must be no private modules between the item and the root of the
+/// crate). If the item is in the root of the crate you'll be fine.
+///
+/// The specified function will be called by the reset handler *after* RAM has been initialized. In
+/// the case of the `thumbv7em-none-eabihf` target the FPU will also be enabled before the function
+/// is called.
+///
+/// The type of the specified function must be `[unsafe] fn() -> !` (never ending function)
+///
+/// # Properties
+///
+/// The entry point will be called by the reset handler. The program can't reference to the entry
+/// point, much less invoke it.
+///
+/// `static mut` variables declared within the entry point are safe to access. The compiler can't
+/// prove this is safe so the attribute will help by making a transformation to the source code: for
+/// this reason a variable like `static mut FOO: u32` will become `let FOO: &'static mut u32;`. Note
+/// that `&'static mut` references have move semantics.
+///
+/// # Examples
+///
+/// - Simple entry point
+///
+/// ``` no_run
+/// # #![no_main]
+/// # use cortex_m_rt_macros::entry;
+/// #[entry]
+/// fn main() -> ! {
+///     loop {
+///         /* .. */
+///     }
+/// }
+/// ```
+///
+/// - `static mut` variables local to the entry point are safe to modify.
+///
+/// ``` no_run
+/// # #![no_main]
+/// # use cortex_m_rt_macros::entry;
+/// #[entry]
+/// fn main() -> ! {
+///     static mut FOO: u32 = 0;
+///
+///     let foo: &'static mut u32 = FOO;
+///     assert_eq!(*foo, 0);
+///     *foo = 1;
+///     assert_eq!(*foo, 1);
+///
+///     loop {
+///         /* .. */
+///     }
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn entry(args: TokenStream, input: TokenStream) -> TokenStream {
+    let f: ItemFn = syn::parse(input).expect("`#[entry]` must be applied to a function");
+
+    // check the function signature
+    assert!(
+        f.constness.is_none()
+            && f.vis == Visibility::Inherited
+            && f.abi.is_none()
+            && f.decl.inputs.is_empty()
+            && f.decl.generics.params.is_empty()
+            && f.decl.generics.where_clause.is_none()
+            && f.decl.variadic.is_none()
+            && match f.decl.output {
+                ReturnType::Default => false,
+                ReturnType::Type(_, ref ty) => match **ty {
+                    Type::Never(_) => true,
+                    _ => false,
+                },
+            },
+        "`#[entry]` function must have signature `[unsafe] fn() -> !`"
+    );
+
+    assert!(
+        args.to_string() == "",
+        "`entry` attribute must have no arguments"
+    );
+
+    // XXX should we blacklist other attributes?
+    let attrs = f.attrs;
+    let ident = f.ident;
+    let (statics, stmts) = extract_static_muts(f.block.stmts);
+
+    let vars = statics
+        .into_iter()
+        .map(|var| {
+            let ident = var.ident;
+            // `let` can't shadow a `static mut` so we must give the `static` a different
+            // name. We'll create a new name by appending an underscore to the original name
+            // of the `static`.
+            let mut ident_ = ident.to_string();
+            ident_.push('_');
+            let ident_ = Ident::new(&ident_, Span::call_site());
+            let ty = var.ty;
+            let expr = var.expr;
+
+            quote!(
+                static mut #ident_: #ty = #expr;
+                #[allow(non_snake_case)]
+                let #ident: &'static mut #ty = unsafe { &mut #ident_ };
+            )
+        }).collect::<Vec<_>>();
+
+    quote!(
+        // TODO(forbid) see tests/compile-fail/entry-hidden.rs
+        // #[forbid(dead_code)]
+        #[export_name = "main"]
+        #(#attrs)*
+        pub fn #ident() -> ! {
+            #(#vars)*
+
+            #(#stmts)*
+        }
+    ).into()
+}
+
+/// Attribute to declare an exception handler
+///
+/// **IMPORTANT**: This attribute must be used on reachable items (i.e. there must be no private
+/// modules between the item and the root of the crate). If the item is in the root of the crate
+/// you'll be fine.
+///
+/// # Syntax
+///
+/// ```
+/// # use cortex_m_rt_macros::exception;
+/// #[exception]
+/// fn SysTick() {
+///     // ..
+/// }
+///
+/// # fn main() {}
+/// ```
+///
+/// where the name of the function must be one of:
+///
+/// - `DefaultHandler`
+/// - `NonMaskableInt`
+/// - `HardFault`
+/// - `MemoryManagement` (a)
+/// - `BusFault` (a)
+/// - `UsageFault` (a)
+/// - `SecureFault` (b)
+/// - `SVCall`
+/// - `DebugMonitor` (a)
+/// - `PendSV`
+/// - `SysTick`
+///
+/// (a) Not available on Cortex-M0 variants (`thumbv6m-none-eabi`)
+///
+/// (b) Only available on ARMv8-M
+///
+/// # Usage
+///
+/// `#[exception] fn HardFault(..` sets the hard fault handler. The handler must have signature
+/// `[unsafe] fn(&ExceptionFrame) -> !`. This handler is not allowed to return as that can cause
+/// undefined behavior.
+///
+/// `#[exception] fn DefaultHandler(..` sets the *default* handler. All exceptions which have not
+/// been assigned a handler will be serviced by this handler. This handler must have signature
+/// `[unsafe] fn(irqn: i16) [-> !]`. `irqn` is the IRQ number (See CMSIS); `irqn` will be a negative
+/// number when the handler is servicing a core exception; `irqn` will be a positive number when the
+/// handler is servicing a device specific exception (interrupt).
+///
+/// `#[exception] fn Name(..` overrides the default handler for the exception with the given `Name`.
+/// These handlers must have signature `[unsafe] fn() [-> !]`. When overriding these other exception
+/// it's possible to add state to them by declaring `static mut` variables at the beginning of the
+/// body of the function. These variables will be safe to access from the function body.
+///
+/// # Properties
+///
+/// Exception handlers can only be called by the hardware. Other parts of the program can't refer to
+/// the exception handlers, much less invoke them as if they were functions.
+///
+/// `static mut` variables declared within an exception handler are safe to access and can be used
+/// to preserve state across invocations of the handler. The compiler can't prove this is safe so
+/// the attribute will help by making a transformation to the source code: for this reason a
+/// variable like `static mut FOO: u32` will become `let FOO: &mut u32;`.
+///
+/// # Examples
+///
+/// - Setting the `HardFault` handler
+///
+/// ```
+/// # extern crate cortex_m_rt;
+/// # extern crate cortex_m_rt_macros;
+/// # use cortex_m_rt_macros::exception;
+/// #[exception]
+/// fn HardFault(ef: &cortex_m_rt::ExceptionFrame) -> ! {
+///     // prints the exception frame as a panic message
+///     panic!("{:#?}", ef);
+/// }
+///
+/// # fn main() {}
+/// ```
+///
+/// - Setting the default handler
+///
+/// ```
+/// # use cortex_m_rt_macros::exception;
+/// #[exception]
+/// fn DefaultHandler(irqn: i16) {
+///     println!("IRQn = {}", irqn);
+/// }
+///
+/// # fn main() {}
+/// ```
+///
+/// - Overriding the `SysTick` handler
+///
+/// ```
+/// extern crate cortex_m_rt as rt;
+///
+/// use rt::exception;
+///
+/// #[exception]
+/// fn SysTick() {
+///     static mut COUNT: i32 = 0;
+///
+///     // `COUNT` is safe to access and has type `&mut i32`
+///     *COUNT += 1;
+///
+///     println!("{}", COUNT);
+/// }
+///
+/// # fn main() {}
+/// ```
+#[proc_macro_attribute]
+pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream {
+    let f: ItemFn = syn::parse(input).expect("`#[exception]` must be applied to a function");
+
+    assert!(
+        args.to_string() == "",
+        "`exception` attribute must have no arguments"
+    );
+
+    let ident = f.ident;
+
+    enum Exception {
+        DefaultHandler,
+        HardFault,
+        Other,
+    }
+
+    let ident_s = ident.to_string();
+    let exn = match &*ident_s {
+        "DefaultHandler" => Exception::DefaultHandler,
+        "HardFault" => Exception::HardFault,
+        // NOTE that at this point we don't check if the exception is available on the target (e.g.
+        // MemoryManagement is not available on Cortex-M0)
+        "NonMaskableInt" | "MemoryManagement" | "BusFault" | "UsageFault" | "SecureFault"
+        | "SVCall" | "DebugMonitor" | "PendSV" | "SysTick" => Exception::Other,
+        _ => panic!("{} is not a valid exception name", ident_s),
+    };
+
+    // XXX should we blacklist other attributes?
+    let attrs = f.attrs;
+    let block = f.block;
+    let stmts = block.stmts;
+
+    let hash = random_ident();
+    match exn {
+        Exception::DefaultHandler => {
+            assert!(
+                f.constness.is_none()
+                    && f.vis == Visibility::Inherited
+                    && f.abi.is_none()
+                    && f.decl.inputs.len() == 1
+                    && f.decl.generics.params.is_empty()
+                    && f.decl.generics.where_clause.is_none()
+                    && f.decl.variadic.is_none()
+                    && match f.decl.output {
+                        ReturnType::Default => true,
+                        ReturnType::Type(_, ref ty) => match **ty {
+                            Type::Tuple(ref tuple) => tuple.elems.is_empty(),
+                            Type::Never(..) => true,
+                            _ => false,
+                        },
+                    },
+                "`DefaultHandler` exception must have signature `[unsafe] fn(i16) [-> !]`"
+            );
+
+            let arg = match f.decl.inputs[0] {
+                FnArg::Captured(ref arg) => arg,
+                _ => unreachable!(),
+            };
+
+            quote!(
+                #[export_name = #ident_s]
+                #(#attrs)*
+                pub extern "C" fn #hash() {
+                    extern crate core;
+
+                    const SCB_ICSR: *const u32 = 0xE000_ED04 as *const u32;
+
+                    let #arg = unsafe { core::ptr::read(SCB_ICSR) as u8 as i16 - 16 };
+
+                    #(#stmts)*
+                }
+            ).into()
+        }
+        Exception::HardFault => {
+            assert!(
+                f.constness.is_none()
+                    && f.vis == Visibility::Inherited
+                    && f.abi.is_none()
+                    && f.decl.inputs.len() == 1
+                    && match f.decl.inputs[0] {
+                        FnArg::Captured(ref arg) => match arg.ty {
+                            Type::Reference(ref r) => {
+                                r.lifetime.is_none() && r.mutability.is_none()
+                            }
+                            _ => false,
+                        },
+                        _ => false,
+                    }
+                    && f.decl.generics.params.is_empty()
+                    && f.decl.generics.where_clause.is_none()
+                    && f.decl.variadic.is_none()
+                    && match f.decl.output {
+                        ReturnType::Default => false,
+                        ReturnType::Type(_, ref ty) => match **ty {
+                            Type::Never(_) => true,
+                            _ => false,
+                        },
+                    },
+                "`HardFault` exception must have signature `[unsafe] fn(&ExceptionFrame) -> !`"
+            );
+
+            let arg = match f.decl.inputs[0] {
+                FnArg::Captured(ref arg) => arg,
+                _ => unreachable!(),
+            };
+
+            let pat = &arg.pat;
+
+            quote!(
+                #[export_name = "UserHardFault"]
+                #(#attrs)*
+                pub extern "C" fn #hash(#arg) -> ! {
+                    extern crate cortex_m_rt;
+
+                    // further type check of the input argument
+                    let #pat: &cortex_m_rt::ExceptionFrame = #pat;
+
+                    #(#stmts)*
+                }
+            ).into()
+        }
+        Exception::Other => {
+            assert!(
+                f.constness.is_none()
+                    && f.vis == Visibility::Inherited
+                    && f.abi.is_none()
+                    && f.decl.inputs.is_empty()
+                    && f.decl.generics.params.is_empty()
+                    && f.decl.generics.where_clause.is_none()
+                    && f.decl.variadic.is_none()
+                    && match f.decl.output {
+                        ReturnType::Default => true,
+                        ReturnType::Type(_, ref ty) => match **ty {
+                            Type::Tuple(ref tuple) => tuple.elems.is_empty(),
+                            Type::Never(..) => true,
+                            _ => false,
+                        },
+                    },
+                "`#[exception]` functions other than `DefaultHandler` and `HardFault` must \
+                 have signature `[unsafe] fn() [-> !]`"
+            );
+
+            let (statics, stmts) = extract_static_muts(stmts);
+
+            let vars = statics
+                .into_iter()
+                .map(|var| {
+                    let ident = var.ident;
+                    // `let` can't shadow a `static mut` so we must give the `static` a different
+                    // name. We'll create a new name by appending an underscore to the original name
+                    // of the `static`.
+                    let mut ident_ = ident.to_string();
+                    ident_.push('_');
+                    let ident_ = Ident::new(&ident_, Span::call_site());
+                    let ty = var.ty;
+                    let expr = var.expr;
+
+                    quote!(
+                    static mut #ident_: #ty = #expr;
+                    #[allow(non_snake_case)]
+                    let #ident: &mut #ty = unsafe { &mut #ident_ };
+                )
+                }).collect::<Vec<_>>();
+
+            quote!(
+                #[export_name = #ident_s]
+                #(#attrs)*
+                pub fn #hash() {
+                    extern crate cortex_m_rt;
+
+                    // check that this exception actually exists
+                    cortex_m_rt::Exception::#ident;
+
+                    #(#vars)*
+
+                    #(#stmts)*
+                }
+            ).into()
+        }
+    }
+}
+
+/// Attribute to mark which function will be called at the beginning of the reset handler.
+///
+/// **IMPORTANT**: This attribute must be used once in the dependency graph and must be used on a
+/// reachable item (i.e. there must be no private modules between the item and the root of the
+/// crate). If the item is in the root of the crate you'll be fine.
+///
+/// The function must have the signature of `unsafe fn()`.
+///
+/// The function passed will be called before static variables are initialized. Any access of static
+/// variables will result in undefined behavior.
+///
+/// # Examples
+///
+/// ```
+/// # use cortex_m_rt_macros::pre_init;
+/// #[pre_init]
+/// unsafe fn before_main() {
+///     // do something here
+/// }
+///
+/// # fn main() {}
+/// ```
+#[proc_macro_attribute]
+pub fn pre_init(args: TokenStream, input: TokenStream) -> TokenStream {
+    let f: ItemFn = syn::parse(input).expect("`#[pre_init]` must be applied to a function");
+
+    // check the function signature
+    assert!(
+        f.constness.is_none()
+            && f.vis == Visibility::Inherited
+            && f.unsafety.is_some()
+            && f.abi.is_none()
+            && f.decl.inputs.is_empty()
+            && f.decl.generics.params.is_empty()
+            && f.decl.generics.where_clause.is_none()
+            && f.decl.variadic.is_none()
+            && match f.decl.output {
+                ReturnType::Default => true,
+                ReturnType::Type(_, ref ty) => match **ty {
+                    Type::Tuple(ref tuple) => tuple.elems.is_empty(),
+                    _ => false,
+                },
+            },
+        "`#[pre_init]` function must have signature `unsafe fn()`"
+    );
+
+    assert!(
+        args.to_string() == "",
+        "`pre_init` attribute must have no arguments"
+    );
+
+    // XXX should we blacklist other attributes?
+    let attrs = f.attrs;
+    let ident = f.ident;
+    let block = f.block;
+
+    quote!(
+        #[export_name = "__pre_init"]
+        #(#attrs)*
+        pub unsafe fn #ident() #block
+    ).into()
+}
+
+// Creates a random identifier
+fn random_ident() -> Ident {
+    let mut rng = rand::thread_rng();
+    Ident::new(
+        &(0..16)
+            .map(|i| {
+                if i == 0 || rng.gen() {
+                    ('a' as u8 + rng.gen::<u8>() % 25) as char
+                } else {
+                    ('0' as u8 + rng.gen::<u8>() % 10) as char
+                }
+            }).collect::<String>(),
+        Span::call_site(),
+    )
+}
+
+/// Extracts `static mut` vars from the beginning of the given statements
+fn extract_static_muts(stmts: Vec<Stmt>) -> (Vec<ItemStatic>, Vec<Stmt>) {
+    let mut istmts = stmts.into_iter();
+
+    let mut statics = vec![];
+    let mut stmts = vec![];
+    while let Some(stmt) = istmts.next() {
+        match stmt {
+            Stmt::Item(Item::Static(var)) => if var.mutability.is_some() {
+                statics.push(var);
+            } else {
+                stmts.push(Stmt::Item(Item::Static(var)));
+            },
+            _ => {
+                stmts.push(stmt);
+                break;
+            }
+        }
+    }
+
+    stmts.extend(istmts);
+
+    (statics, stmts)
+}
diff --git a/cortex-m-rt/src/lib.rs b/cortex-m-rt/src/lib.rs
index 10f60f6..17c4a63 100644
--- a/cortex-m-rt/src/lib.rs
+++ b/cortex-m-rt/src/lib.rs
@@ -14,9 +14,16 @@
 //!
 //! - Enabling the FPU before the program entry point if the target is `thumbv7em-none-eabihf`.
 //!
-//! This crate also provides a mechanism to set exception handlers: see the [`exception!`] macro.
+//! This crate also provides the following attributes:
 //!
-//! [`exception!`]: macro.exception.html
+//! - [`#[entry]`] to declare the entry point of the program
+//! - [`#[exception]`] to override an exception handler. If not overridden all exception handlers
+//!   default to an infinite loop.
+//! - [`#[pre_init]`] to run code *before* `static` variables are initialized
+//!
+//! [`#[entry]`]: ../cortex_m_rt_macros/fn.entry.html
+//! [`#[exception]`]: ../cortex_m_rt_macros/fn.exception.html
+//! [`#[pre_init]`]: ../cortex_m_rt_macros/fn.pre_init.html
 //!
 //! # Requirements
 //!
@@ -87,25 +94,23 @@
 //! This section presents a minimal application built on top of `cortex-m-rt`. Apart from the
 //! mandatory `memory.x` linker script describing the memory layout of the device, the hard fault
 //! handler and the default exception handler must also be defined somewhere in the dependency
-//! graph (cf. [`exception!`]). In this example we define them in the binary crate:
+//! graph (see [`#[exception]`]). In this example we define them in the binary crate:
 //!
 //! ``` ignore
 //! // IMPORTANT the standard `main` interface is not used because it requires nightly
 //! #![no_main]
 //! #![no_std]
 //!
-//! #[macro_use(entry, exception)]
 //! extern crate cortex_m_rt as rt;
 //!
 //! // makes `panic!` print messages to the host stderr using semihosting
 //! extern crate panic_semihosting;
 //!
-//! use rt::ExceptionFrame;
+//! use rt::entry;
 //!
 //! // use `main` as the entry point of this application
-//! entry!(main);
-//!
 //! // `main` is not allowed to return
+//! #[entry]
 //! fn main() -> ! {
 //!     // initialization
 //!
@@ -113,20 +118,6 @@
 //!         // application logic
 //!     }
 //! }
-//!
-//! // define the hard fault handler
-//! exception!(HardFault, hard_fault);
-//!
-//! fn hard_fault(ef: &ExceptionFrame) -> ! {
-//!     panic!("{:#?}", ef);
-//! }
-//!
-//! // define the default exception handler
-//! exception!(*, default_handler);
-//!
-//! fn default_handler(irqn: i16) {
-//!     panic!("unhandled exception (IRQn={})", irqn);
-//! }
 //! ```
 //!
 //! To actually build this program you need to place a `memory.x` linker script somewhere the linker
@@ -207,15 +198,15 @@
 //!
 //! [`entry!`]:  macro.entry.html
 //!
-//! - `DefaultHandler`. This is the default handler. This function will contain, or call, the
-//! function you declared in the second argument of `exception!(*, ..)`.
+//! - `DefaultHandler`. This is the default handler. If not overridden using `#[exception] fn
+//! DefaultHandler(..` this will be an infinite loop.
 //!
 //! - `HardFault`. This is the hard fault handler. This function is simply a trampoline that jumps
-//! into the user defined hard fault handler: `UserHardFault`. The trampoline is required to set up
-//! the pointer to the stacked exception frame.
+//! into the user defined hard fault handler named `UserHardFault`. The trampoline is required to
+//! set up the pointer to the stacked exception frame.
 //!
-//! - `UserHardFault`. This is the user defined hard fault handler. This function will contain, or
-//! call, the function you declared in the second argument of `exception!(HardFault, ..)`
+//! - `UserHardFault`. This is the user defined hard fault handler. If not overridden using
+//! `#[exception] fn HardFault(..` this will be an infinite loop.
 //!
 //! - `__STACK_START`. This is the first entry in the `.vector_table` section. This symbol contains
 //! the initial value of the stack pointer; this is where the stack will be located -- the stack
@@ -356,8 +347,8 @@
 //! PROVIDE(Bar = DefaultHandler);
 //! ```
 //!
-//! This weakly aliases both `Foo` and `Bar`. `DefaultHandler` is the default exception handler that
-//! the user provides via `exception!(*, ..)` and that the core exceptions use unless overridden.
+//! This weakly aliases both `Foo` and `Bar`. `DefaultHandler` is the default exception handler and
+//! that the core exceptions use unless overridden.
 //!
 //! Because this linker script is provided by a dependency of the final application the dependency
 //! must contain build script that puts `device.x` somewhere the linker can find. An example of such
@@ -397,11 +388,14 @@
 #![deny(warnings)]
 #![no_std]
 
+extern crate cortex_m_rt_macros as macros;
 extern crate r0;
 
 use core::fmt;
 use core::sync::atomic::{self, Ordering};
 
+pub use macros::{entry, exception, pre_init};
+
 /// Registers stacked (pushed into the stack) during an exception
 #[derive(Clone, Copy)]
 #[repr(C)]
@@ -474,8 +468,6 @@ pub static __RESET_VECTOR: unsafe extern "C" fn() -> ! = Reset;
 #[no_mangle]
 pub unsafe extern "C" fn Reset() -> ! {
     extern "C" {
-        // This symbol will be provided by the user via the `entry!` macro
-        fn main() -> !;
 
         // These symbols come from `link.x`
         static mut __sbss: u32;
@@ -485,11 +477,17 @@ pub unsafe extern "C" fn Reset() -> ! {
         static mut __edata: u32;
         static __sidata: u32;
 
+    }
+
+    extern "Rust" {
+        // This symbol will be provided by the user via `#[entry]`
+        fn main() -> !;
+
+        // This symbol will be provided by the user via `#[pre_init]`
         fn __pre_init();
     }
 
-    let pre_init: unsafe extern "C" fn() = __pre_init;
-    pre_init();
+    __pre_init();
 
     // Initialize RAM
     r0::zero_bss(&mut __sbss, &mut __ebss);
@@ -551,31 +549,6 @@ pub unsafe extern "C" fn DefaultHandler_() -> ! {
 #[no_mangle]
 pub unsafe extern "C" fn DefaultPreInit() {}
 
-/// Macro to define the entry point of the program
-///
-/// **NOTE** This macro must be invoked once and must be invoked from an accessible module, ideally
-/// from the root of the crate.
-///
-/// Usage: `entry!(path::to::entry::point)`
-///
-/// The specified function will be called by the reset handler *after* RAM has been initialized. In
-/// the case of the `thumbv7em-none-eabihf` target the FPU will also be enabled before the function
-/// is called.
-///
-/// The signature of the specified function must be `fn() -> !` (never ending function)
-#[macro_export]
-macro_rules! entry {
-    ($path:expr) => {
-        #[export_name = "main"]
-        pub extern "C" fn __impl_main() -> ! {
-            // validate the signature of the program entry point
-            let f: fn() -> ! = $path;
-
-            f()
-        }
-    };
-}
-
 /* Exceptions */
 #[doc(hidden)]
 pub enum Exception {
@@ -721,206 +694,3 @@ pub static __INTERRUPTS: [unsafe extern "C" fn(); 32] = [{
 
     DefaultHandler
 }; 32];
-
-/// Macro to set or override a processor core exception handler
-///
-/// **NOTE** This macro must be invoked from an accessible module, ideally from the root of the
-/// crate.
-///
-/// # Syntax
-///
-/// ``` ignore
-/// exception!(
-///     // Name of the exception
-///     $Name:ident,
-///
-///     // Path to the exception handler (a function)
-///     $handler:expr,
-///
-///     // Optional, state preserved across invocations of the handler
-///     state: $State:ty = $initial_state:expr,
-/// );
-/// ```
-///
-/// where `$Name` can be one of:
-///
-/// - `*`
-/// - `NonMaskableInt`
-/// - `HardFault`
-/// - `MemoryManagement` (a)
-/// - `BusFault` (a)
-/// - `UsageFault` (a)
-/// - `SecureFault` (b)
-/// - `SVCall`
-/// - `DebugMonitor` (a)
-/// - `PendSV`
-/// - `SysTick`
-///
-/// (a) Not available on Cortex-M0 variants (`thumbv6m-none-eabi`)
-///
-/// (b) Only available on ARMv8-M
-///
-/// # Usage
-///
-/// `exception!(HardFault, ..)` sets the hard fault handler. The handler must have signature
-/// `fn(&ExceptionFrame) -> !`. This handler is not allowed to return as that can cause undefined
-/// behavior. It's mandatory to set the `HardFault` handler somewhere in the dependency graph of an
-/// application.
-///
-/// `exception!(*, ..)` sets the *default* handler. All exceptions which have not been assigned a
-/// handler will be serviced by this handler. This handler must have signature `fn(irqn: i16)`.
-/// `irqn` is the IRQ number (cf. CMSIS); `irqn` will be a negative number when the handler is
-/// servicing a core exception; `irqn` will be a positive number when the handler is servicing a
-/// device specific exception (interrupt). It's mandatory to set the default handler somewhere
-/// in the dependency graph of an application.
-///
-/// `exception!($Exception, ..)` overrides the default handler for `$Exception`. All exceptions,
-/// except for `HardFault`, can be assigned some `$State`.
-///
-/// # Examples
-///
-/// - Setting the `HardFault` handler
-///
-/// ```
-/// #[macro_use(exception)]
-/// extern crate cortex_m_rt as rt;
-///
-/// use rt::ExceptionFrame;
-///
-/// exception!(HardFault, hard_fault);
-///
-/// fn hard_fault(ef: &ExceptionFrame) -> ! {
-///     // prints the exception frame as a panic message
-///     panic!("{:#?}", ef);
-/// }
-///
-/// # fn main() {}
-/// ```
-///
-/// - Setting the default handler
-///
-/// ```
-/// #[macro_use(exception)]
-/// extern crate cortex_m_rt as rt;
-///
-/// exception!(*, default_handler);
-///
-/// fn default_handler(irqn: i16) {
-///     println!("IRQn = {}", irqn);
-/// }
-///
-/// # fn main() {}
-/// ```
-///
-/// - Overriding the `SysTick` handler
-///
-/// ```
-/// #[macro_use(exception)]
-/// extern crate cortex_m_rt as rt;
-///
-/// exception!(SysTick, sys_tick, state: u32 = 0);
-///
-/// fn sys_tick(count: &mut u32) {
-///     println!("count = {}", *count);
-///
-///     *count += 1;
-/// }
-///
-/// # fn main() {}
-/// ```
-#[macro_export]
-macro_rules! exception {
-    (* , $handler:expr) => {
-        #[allow(unsafe_code)]
-        #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible
-        #[no_mangle]
-        pub unsafe extern "C" fn DefaultHandler() {
-            extern crate core;
-
-            // validate the signature of the user provided handler
-            let f: fn(i16) = $handler;
-
-            const SCB_ICSR: *const u32 = 0xE000_ED04 as *const u32;
-
-            // NOTE not volatile so the compiler can opt the load operation away if the value is
-            // unused
-            f(core::ptr::read(SCB_ICSR) as u8 as i16 - 16)
-        }
-    };
-
-    (HardFault, $handler:expr) => {
-        #[allow(unsafe_code)]
-        #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible
-        #[no_mangle]
-        pub unsafe extern "C" fn UserHardFault(ef: &$crate::ExceptionFrame) {
-            // validate the signature of the user provided handler
-            let f: fn(&$crate::ExceptionFrame) -> ! = $handler;
-
-            f(ef)
-        }
-    };
-
-    ($Name:ident, $handler:expr,state: $State:ty = $initial_state:expr) => {
-        #[allow(unsafe_code)]
-        #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible
-        #[no_mangle]
-        pub unsafe extern "C" fn $Name() {
-            static mut STATE: $State = $initial_state;
-
-            // check that this exception exists
-            let _ = $crate::Exception::$Name;
-
-            // validate the signature of the user provided handler
-            let f: fn(&mut $State) = $handler;
-
-            f(&mut STATE)
-        }
-    };
-
-    ($Name:ident, $handler:expr) => {
-        #[allow(unsafe_code)]
-        #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible
-        #[no_mangle]
-        pub unsafe extern "C" fn $Name() {
-            // check that this exception exists
-            let _ = $crate::Exception::$Name;
-
-            // validate the signature of the user provided handler
-            let f: fn() = $handler;
-
-            f()
-        }
-    };
-}
-
-/// Macro to set the function to be called at the beginning of the reset handler.
-///
-/// The function must have the signature of `unsafe fn()`.
-///
-/// The function passed will be called before static variables are initialized. Any access of static
-/// variables will result in undefined behavior.
-///
-/// # Examples
-///
-/// ``` ignore
-/// pre_init!(foo::bar);
-///
-/// mod foo {
-///     pub unsafe fn bar() {
-///         // do something here
-///     }
-/// }
-/// ```
-#[macro_export]
-macro_rules! pre_init {
-    ($handler:path) => {
-        #[allow(unsafe_code)]
-        #[deny(private_no_mangle_fns)] // raise an error if this item is not accessible
-        #[no_mangle]
-        pub unsafe extern "C" fn __pre_init() {
-            // validate user handler
-            let f: unsafe fn() = $handler;
-            f();
-        }
-    };
-}
diff --git a/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-1.rs b/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-1.rs
new file mode 100644
index 0000000..037e9c8
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-1.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `DefaultHandler` exception must have signature `[unsafe] fn(i16) [-> !]`
+fn DefaultHandler(_irqn: i16, undef: u32) {}
diff --git a/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-2.rs b/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-2.rs
new file mode 100644
index 0000000..8fc4a7e
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/default-handler-bad-signature-2.rs
@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `DefaultHandler` exception must have signature `[unsafe] fn(i16) [-> !]`
+fn DefaultHandler(_irqn: i16) -> u32 {
+    0
+}
diff --git a/cortex-m-rt/tests/compile-fail/default-handler-hidden.rs b/cortex-m-rt/tests/compile-fail/default-handler-hidden.rs
new file mode 100644
index 0000000..059c10b
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/default-handler-hidden.rs
@@ -0,0 +1,22 @@
+// ignore-test :sadface: it's not possible to prevent this user error at compile time
+// see rust-lang/rust#53975 for details
+
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+mod hidden {
+    use cortex_m_rt::exception;
+
+    #[exception]
+    fn DefaultHandler(_irqn: i16) {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/default-handler-twice.rs b/cortex-m-rt/tests/compile-fail/default-handler-twice.rs
new file mode 100644
index 0000000..7d6ad98
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/default-handler-twice.rs
@@ -0,0 +1,22 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+fn DefaultHandler(_irqn: i16) {}
+
+pub mod reachable {
+    use cortex_m_rt::exception;
+
+    #[exception] //~ ERROR symbol `DefaultHandler` is already defined
+    fn DefaultHandler(_irqn: i16) {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/entry-args.rs b/cortex-m-rt/tests/compile-fail/entry-args.rs
new file mode 100644
index 0000000..07cb4bd
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-args.rs
@@ -0,0 +1,13 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry(foo)] //~ ERROR custom attribute panicked
+//~^ HELP `entry` attribute must have no arguments
+fn foo() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/entry-bad-signature-1.rs b/cortex-m-rt/tests/compile-fail/entry-bad-signature-1.rs
new file mode 100644
index 0000000..5eeb49f
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-bad-signature-1.rs
@@ -0,0 +1,11 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry] //~ ERROR custom attribute panicked
+//~^ HELP `#[entry]` function must have signature `[unsafe] fn() -> !`
+fn foo() {}
diff --git a/cortex-m-rt/tests/compile-fail/entry-bad-signature-2.rs b/cortex-m-rt/tests/compile-fail/entry-bad-signature-2.rs
new file mode 100644
index 0000000..18bbaed
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-bad-signature-2.rs
@@ -0,0 +1,11 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry] //~ ERROR custom attribute panicked
+//~^ HELP `#[entry]` function must have signature `[unsafe] fn() -> !`
+fn foo(undef: i32) -> ! {}
diff --git a/cortex-m-rt/tests/compile-fail/entry-bad-signature-3.rs b/cortex-m-rt/tests/compile-fail/entry-bad-signature-3.rs
new file mode 100644
index 0000000..09b75e9
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-bad-signature-3.rs
@@ -0,0 +1,13 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry] //~ ERROR custom attribute panicked
+//~^ HELP `#[entry]` function must have signature `[unsafe] fn() -> !`
+extern "C" fn foo() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/entry-hidden.rs b/cortex-m-rt/tests/compile-fail/entry-hidden.rs
new file mode 100644
index 0000000..7d74063
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-hidden.rs
@@ -0,0 +1,19 @@
+// ignore-test :sadface: it's not possible to prevent this user error at compile time
+// see rust-lang/rust#53975 for details
+
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+mod hidden {
+    use cortex_m_rt::entry;
+
+    // this function needs to be "reachable" (all modules between it and the crate root must be
+    // `pub`) or linking will fail
+    #[entry]
+    fn foo() -> ! { //~ ERROR function is never used
+        loop {}
+    }
+}
diff --git a/cortex-m-rt/tests/compile-fail/entry-twice.rs b/cortex-m-rt/tests/compile-fail/entry-twice.rs
new file mode 100644
index 0000000..b2819f6
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/entry-twice.rs
@@ -0,0 +1,17 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::entry;
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[entry] //~ ERROR symbol `main` is already defined
+fn bar() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/exception-args.rs b/cortex-m-rt/tests/compile-fail/exception-args.rs
new file mode 100644
index 0000000..85613ff
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/exception-args.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception(SysTick)] //~ ERROR custom attribute panicked
+//~^ HELP `exception` attribute must have no arguments
+fn SysTick() {}
diff --git a/cortex-m-rt/tests/compile-fail/exception-bad-signature-1.rs b/cortex-m-rt/tests/compile-fail/exception-bad-signature-1.rs
new file mode 100644
index 0000000..966493e
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/exception-bad-signature-1.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `#[exception]` functions other than `DefaultHandler` and `HardFault` must have signature `[unsafe] fn() [-> !]`
+fn SysTick(undef: u32) {}
diff --git a/cortex-m-rt/tests/compile-fail/exception-bad-signature-2.rs b/cortex-m-rt/tests/compile-fail/exception-bad-signature-2.rs
new file mode 100644
index 0000000..8504771
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/exception-bad-signature-2.rs
@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `#[exception]` functions other than `DefaultHandler` and `HardFault` must have signature `[unsafe] fn() [-> !]`
+fn SysTick() -> u32 {
+    0
+}
diff --git a/cortex-m-rt/tests/compile-fail/exception-hidden.rs b/cortex-m-rt/tests/compile-fail/exception-hidden.rs
new file mode 100644
index 0000000..053c81c
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/exception-hidden.rs
@@ -0,0 +1,22 @@
+// ignore-test :sadface: it's not possible to prevent this user error at compile time
+// see rust-lang/rust#53975 for details
+
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+mod hidden {
+    use cortex_m_rt::exception;
+
+    #[exception]
+    fn SysTick() {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/exception-twice.rs b/cortex-m-rt/tests/compile-fail/exception-twice.rs
new file mode 100644
index 0000000..5377fce
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/exception-twice.rs
@@ -0,0 +1,22 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+fn SysTick() {}
+
+pub mod reachable {
+    use cortex_m_rt::exception;
+
+    #[exception] //~ ERROR symbol `SysTick` is already defined
+    fn SysTick() {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/hard-fault-bad-signature-1.rs b/cortex-m-rt/tests/compile-fail/hard-fault-bad-signature-1.rs
new file mode 100644
index 0000000..83fda5f
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/hard-fault-bad-signature-1.rs
@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `HardFault` exception must have signature `[unsafe] fn(&ExceptionFrame) -> !`
+fn HardFault(_ef: &ExceptionFrame, undef: u32) -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/hard-fault-hidden.rs b/cortex-m-rt/tests/compile-fail/hard-fault-hidden.rs
new file mode 100644
index 0000000..31237c4
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/hard-fault-hidden.rs
@@ -0,0 +1,24 @@
+// ignore-test :sadface: it's not possible to prevent this user error at compile time
+// see rust-lang/rust#53975 for details
+
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+mod hidden {
+    use cortex_m_rt::{exception, ExceptionFrame};
+
+    #[exception]
+    fn HardFault(_ef: &ExceptionFrame) -> ! {
+        loop {}
+    }
+}
diff --git a/cortex-m-rt/tests/compile-fail/hard-fault-twice.rs b/cortex-m-rt/tests/compile-fail/hard-fault-twice.rs
new file mode 100644
index 0000000..90270e5
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/hard-fault-twice.rs
@@ -0,0 +1,26 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception]
+fn HardFault(_ef: &ExceptionFrame) -> ! {
+    loop {}
+}
+
+pub mod reachable {
+    use cortex_m_rt::{exception, ExceptionFrame};
+
+    #[exception] //~ ERROR symbol `UserHardFault` is already defined
+    fn HardFault(_ef: &ExceptionFrame) -> ! {
+        loop {}
+    }
+}
diff --git a/cortex-m-rt/tests/compile-fail/pre-init-args.rs b/cortex-m-rt/tests/compile-fail/pre-init-args.rs
new file mode 100644
index 0000000..716b211
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/pre-init-args.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, pre_init};
+
+#[pre_init(foo)] //~ ERROR custom attribute panicked
+//~^ HELP `pre_init` attribute must have no arguments
+unsafe fn foo() {}
+
+#[entry]
+fn baz() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-1.rs b/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-1.rs
new file mode 100644
index 0000000..58d3022
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-1.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, pre_init};
+
+#[pre_init] //~ ERROR custom attribute panicked
+//~^ HELP `#[pre_init]` function must have signature `unsafe fn()`
+fn foo() {}
+
+#[entry]
+fn bar() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-2.rs b/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-2.rs
new file mode 100644
index 0000000..e47ed59
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/pre-init-bad-signature-2.rs
@@ -0,0 +1,16 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, pre_init};
+
+#[pre_init] //~ ERROR custom attribute panicked
+//~^ HELP `#[pre_init]` function must have signature `unsafe fn()`
+unsafe fn foo(undef: i32) {}
+
+#[entry]
+fn bar() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/pre-init-hidden.rs b/cortex-m-rt/tests/compile-fail/pre-init-hidden.rs
new file mode 100644
index 0000000..f512d62
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/pre-init-hidden.rs
@@ -0,0 +1,23 @@
+// ignore-test :sadface: it's not possible to prevent this user error at compile time
+// see rust-lang/rust#53975 for details
+
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+mod hidden {
+    use cortex_m_rt::pre_init;
+
+    // this function needs to be "reachable" (all modules between it and the crate root must be
+    // `pub`) or the function will be ignored
+    #[entry]
+    unsafe fn pre_init() {} //~ ERROR function is never used
+}
+
+#[entry]
+fn foo() -> ! {
+    //~ ERROR function is never used
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compile-fail/pre-init-twice.rs b/cortex-m-rt/tests/compile-fail/pre-init-twice.rs
new file mode 100644
index 0000000..5fb1ade
--- /dev/null
+++ b/cortex-m-rt/tests/compile-fail/pre-init-twice.rs
@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, pre_init};
+
+#[pre_init]
+unsafe fn foo() {}
+
+#[pre_init] //~ ERROR symbol `__pre_init` is already defined
+unsafe fn bar() {}
+
+#[entry]
+fn baz() -> ! {
+    loop {}
+}
diff --git a/cortex-m-rt/tests/compiletest.rs b/cortex-m-rt/tests/compiletest.rs
new file mode 100644
index 0000000..6cea3ac
--- /dev/null
+++ b/cortex-m-rt/tests/compiletest.rs
@@ -0,0 +1,21 @@
+extern crate compiletest_rs as compiletest;
+
+use std::path::PathBuf;
+
+fn run_mode(mode: &'static str) {
+    let mut config = compiletest::Config::default();
+
+    config.mode = mode.parse().expect("Invalid mode");
+    config.src_base = PathBuf::from(format!("tests/{}", mode));
+    // config.link_deps(); // Populate config.target_rustcflags with dependencies on the path
+    config.target_rustcflags =
+        Some("-L target/debug -L target/debug/deps -C panic=abort".to_owned());
+    // config.clean_rmeta(); // If your tests import the parent crate, this helps with E0464
+
+    compiletest::run_tests(&config);
+}
+
+#[test]
+fn compile_test() {
+    run_mode("compile-fail");
+}