feat: hack in support for tsconfig `extends` (#1147)

* hack in support for extends

* Update src/resolver/resolver.zig

Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>

* wip review fixes

* fix style

Co-authored-by: Victor Lin <victor.lin@airbnb.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
Co-authored-by: Victor Lin <vlin@twitter.com>

2 files changed, 47 insertions, 14 deletions

diff --git a/src/resolver/resolver.zig b/src/resolver/resolver.zig
index 8dbbba50e..97e4194b0 100644
--- a/src/resolver/resolver.zig
+++ b/src/resolver/resolver.zig
@@ -234,6 +234,7 @@ threadlocal var check_browser_map_buf: [bun.MAX_PATH_BYTES]u8 = undefined;
 threadlocal var remap_path_buf: [bun.MAX_PATH_BYTES]u8 = undefined;
 threadlocal var load_as_file_buf: [bun.MAX_PATH_BYTES]u8 = undefined;
 threadlocal var remap_path_trailing_slash: [bun.MAX_PATH_BYTES]u8 = undefined;
+threadlocal var tsconfig_paths_buf: [bun.MAX_PATH_BYTES]u8 = undefined;
 
 pub const DebugLogs = struct {
     what: string = "",
@@ -1771,8 +1772,8 @@ pub const Resolver = struct {
             const original_paths = entry.value_ptr.*;
 
             if (strings.indexOfChar(key, '*')) |star| {
-                const prefix = key[0 .. star - 1];
-                const suffix = key[star + 1 ..];
+                const prefix = if (star == 0) "" else key[0..star];
+                const suffix = if (star == key.len - 1) "" else key[star + 1 ..];
 
                 // Find the match with the longest prefix. If two matches have the same
                 // prefix length, pick the one with the longest suffix. This second edge
@@ -2697,6 +2698,45 @@ pub const Resolver = struct {
                     }
                     break :brk null;
                 };
+                if (info.tsconfig_json) |tsconfig_json| {
+                    var parent_configs = try std.BoundedArray(*TSConfigJSON, 64).init(0);
+                    try parent_configs.append(tsconfig_json);
+                    var current = tsconfig_json;
+                    while (current.extends.len > 0) {
+                        var ts_dir_name = Dirname.dirname(current.abs_path);
+                        // not sure why this needs cwd but we'll just pass in the dir of the tsconfig...
+                        var abs_path = ResolvePath.joinAbsStringBuf(ts_dir_name, &tsconfig_path_abs_buf, &[_]string{ ts_dir_name, current.extends }, .auto);
+                        var parent_config_maybe = try r.parseTSConfig(abs_path, 0);
+                        if (parent_config_maybe) |parent_config| {
+                            try parent_configs.append(parent_config);
+                            current = parent_config;
+                        } else {
+                            break;
+                        }
+                    }
+
+                    var merged_config = parent_configs.pop();
+                    // starting from the base config (end of the list)
+                    // successively apply the inheritable attributes to the next config
+                    while (parent_configs.popOrNull()) |parent_config| {
+                        if (parent_config.base_url.len > 0) {
+                            merged_config.base_url = parent_config.base_url;
+                            merged_config.base_url_for_paths = parent_config.base_url_for_paths;
+                        }
+                        merged_config.jsx = parent_config.mergeJSX(merged_config.jsx);
+
+                        if (parent_config.preserve_imports_not_used_as_values) |value| {
+                            merged_config.preserve_imports_not_used_as_values = value;
+                        }
+
+                        var iter = parent_config.paths.iterator();
+                        while (iter.next()) |c| {
+                            merged_config.paths.put(c.key_ptr.*, c.value_ptr.*) catch unreachable;
+                        }
+                        // todo deinit these parent configs somehow?
+                    }
+                    info.tsconfig_json = merged_config;
+                }
                 info.enclosing_tsconfig_json = info.tsconfig_json;
             }
         }
diff --git a/src/resolver/tsconfig_json.zig b/src/resolver/tsconfig_json.zig
index 34732beb8..d3a6a2062 100644
--- a/src/resolver/tsconfig_json.zig
+++ b/src/resolver/tsconfig_json.zig
@@ -33,6 +33,7 @@ pub const TSConfigJSON = struct {
     // More info: https://github.com/microsoft/TypeScript/issues/31869
     base_url_for_paths: string = "",
 
+    extends: string = "",
     // The verbatim values of "compilerOptions.paths". The keys are patterns to
     // match and the values are arrays of fallback paths to search. Each key and
     // each fallback path can optionally have a single "*" wildcard character.
@@ -49,7 +50,7 @@ pub const TSConfigJSON = struct {
 
     use_define_for_class_fields: ?bool = null,
 
-    preserve_imports_not_used_as_values: bool = false,
+    preserve_imports_not_used_as_values: ?bool = false,
 
     pub fn hasBaseURL(tsconfig: *const TSConfigJSON) bool {
         return tsconfig.base_url.len > 0;
@@ -108,18 +109,10 @@ pub const TSConfigJSON = struct {
         errdefer allocator.free(result.paths);
         if (json.asProperty("extends")) |extends_value| {
             if (!source.path.isNodeModule()) {
-                log.addWarning(&source, extends_value.loc, "\"extends\" is not implemented yet") catch unreachable;
+                if (extends_value.expr.asString(allocator) orelse null) |str| {
+                    result.extends = str;
+                }
             }
-            // if ((extends_value.expr.asString(allocator) catch null)) |str| {
-            //     if (extends(str, source.rangeOfString(extends_value.loc))) |base| {
-            //         result.jsx = base.jsx;
-            //         result.base_url_for_paths = base.base_url_for_paths;
-            //         result.use_define_for_class_fields = base.use_define_for_class_fields;
-            //         result.preserve_imports_not_used_as_values = base.preserve_imports_not_used_as_values;
-            //         //  https://github.com/microsoft/TypeScript/issues/14527#issuecomment-284948808
-            //         result.paths = base.paths;
-            //     }
-            // }
         }
         var has_base_url = false;