fix: output .map files alongside .js within out_dir

examples/out_dir/BUILD.bazel

@@ -0,0 +1,27 @@
+load("@aspect_rules_swc//swc:defs.bzl", "swc")
+load("@aspect_bazel_lib//lib:testing.bzl", "assert_outputs")
+
+swc(
+    name = "transpile",
+    srcs = [
+        "a.ts",
+        "b.ts",
+    ],
+    out_dir = "out",
+    source_maps = "true",
+)
+
+# Since the srcs were in a filegroup, the swc macro cannot pre-declare the outputs.
+# So there is no label ":a.js" that we can reference from the build file.
+# However, a.js is still produced as one of the default outputs of the transpile rule.
+# We can verify this in an action that depends on the ":transpile" rule and reads the files.
+assert_outputs(
+    name = "check_outputs",
+    actual = "transpile",
+    expected = [
+        "examples/out_dir/out/a.js",
+        "examples/out_dir/out/a.js.map",
+        "examples/out_dir/out/b.js",
+        "examples/out_dir/out/b.js.map",
+    ],
+)

examples/out_dir/a.ts

@@ -0,0 +1 @@
+export const a: string = "a";

examples/out_dir/b.ts

@@ -0,0 +1 @@
+export const b: string = "b";

examples/out_dir/check_outputs.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+set -o errexit
+
+cd "$TEST_SRCDIR/$TEST_WORKSPACE/$(dirname $TEST_TARGET)"
+grep "export var a" out_dir/out/a.js
+grep "sourceMappingURL=a.js.map" out_dir/out/a.js
+grep --fixed-strings '"sources":["../a.ts"]' out_dir/out/a.js.map
+
+grep "export var b" out_dir/out/b.js
+grep "sourceMappingURL=b.js.map" out_dir/out/b.js
+grep --fixed-strings '"sources":["../b.ts"]' out_dir/out/b.js.map

swc/defs.bzl

@@ -68,7 +68,7 @@ def swc(name, srcs = None, args = [], data = [], output_dir = False, swcrc = Non
 
     if not output_dir:
         js_outs = _swc_lib.calculate_js_outs(srcs, out_dir)
-        map_outs = _swc_lib.calculate_map_outs(srcs, source_maps)
+        map_outs = _swc_lib.calculate_map_outs(srcs, out_dir, source_maps)
 
     swc_transpiler(
         name = name,

swc/private/swc.bzl

@@ -79,10 +79,15 @@ def _calculate_js_outs(srcs, out_dir = None):
 
     return js_outs
 
-def _calculate_map_outs(srcs, source_maps):
+def _calculate_map_outs(srcs, out_dir, source_maps):
     if source_maps in ["false", "inline"]:
         return []
-    return [paths.replace_extension(f, ".js.map") for f in srcs if _is_supported_src(f)]
+
+    map_outs = [paths.replace_extension(f, ".js.map") for f in srcs if _is_supported_src(f)]
+    if out_dir != None:
+        map_outs = [paths.join(out_dir, f) for f in map_outs]
+
+    return map_outs
 
 def _impl(ctx):
     swcinfo = ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo
@@ -133,7 +138,7 @@ def _impl(ctx):
         if len(ctx.attr.map_outs):
             map_outs = ctx.outputs.map_outs
         else:
-            map_outs = _declare_outputs(ctx, _calculate_map_outs(srcs, ctx.attr.source_maps))
+            map_outs = _declare_outputs(ctx, _calculate_map_outs(srcs, ctx.attr.out_dir, ctx.attr.source_maps))
 
         output_sources = js_outs + map_outs