fix: Handle dot root dir depth

examples/root_dir/BUILD.bazel

@@ -14,6 +14,30 @@ swc(
     source_maps = True,
 )
 
+# Test case for root_dir="." (should have depth 0)
+swc(
+    name = "compile_dot",
+    srcs = [
+        "src/a.ts",
+        "src/b.ts",
+        "src/sub/c.ts",
+    ],
+    out_dir = "out_dot",
+    root_dir = ".",
+    source_maps = True,
+)
+
+# Test case for nested root_dir
+swc(
+    name = "compile_nested",
+    srcs = [
+        "src/sub/c.ts",
+    ],
+    out_dir = "out_nested",
+    root_dir = "src/sub",
+    source_maps = True,
+)
+
 # Assert that the output of "compile" rule matches the expected file.
 write_source_files(
     name = "test",
@@ -23,6 +47,24 @@ write_source_files(
     },
 )
 
+# Assert outputs for dot root_dir test
+write_source_files(
+    name = "test_dot",
+    files = {
+        "expected_dot/src/a.js": ":out_dot/src/a.js",
+        "expected_dot/src/b.js": ":out_dot/src/b.js",
+        "expected_dot/src/sub/c.js": ":out_dot/src/sub/c.js",
+    },
+)
+
+# Assert outputs for nested root_dir test
+write_source_files(
+    name = "test_nested",
+    files = {
+        "expected_nested/c.js": ":out_nested/c.js",
+    },
+)
+
 [
     assert_json_matches(
         name = "test_%s" % f.replace("/", "-"),
@@ -37,3 +79,26 @@ write_source_files(
         "sub/c",
     ]
 ]
+
+[
+    assert_json_matches(
+        name = "test_dot_%s" % f.replace("/", "-"),
+        file1 = ":out_dot/%s.js.map" % f,
+        file2 = "expected_dot/%s.js.map.golden" % f,
+        filter1 = ".sourceRoot,.sources",
+        filter2 = ".sourceRoot,.sources",
+    )
+    for f in [
+        "src/a",
+        "src/b",
+        "src/sub/c",
+    ]
+]
+
+assert_json_matches(
+    name = "test_nested_c",
+    file1 = ":out_nested/c.js.map",
+    file2 = "expected_nested/c.js.map.golden",
+    filter1 = ".sourceRoot,.sources",
+    filter2 = ".sourceRoot,.sources",
+)

examples/root_dir/expected_dot/src/a.js.map.golden

@@ -0,0 +1,5 @@
+{
+    "sources": [
+        "../../src/a.ts"
+    ]
+}

examples/root_dir/expected_dot/src/b.js.map.golden

@@ -0,0 +1,5 @@
+{
+    "sources": [
+        "../../src/b.ts"
+    ]
+}

examples/root_dir/expected_dot/src/sub/c.js.map.golden

@@ -0,0 +1,5 @@
+{
+    "sources": [
+        "../../../src/sub/c.ts"
+    ]
+}

examples/root_dir/expected_nested/c.js.map.golden

@@ -0,0 +1,5 @@
+{
+    "sources": [
+        "../src/sub/c.ts"
+    ]
+}

swc/private/swc.bzl

@@ -245,7 +245,7 @@ def _calculate_source_file(ctx, src):
     # out of src subdir
     if src_pkg:
         src_pkg_depth = len(src_pkg.split("/"))
-        root_dir_depth = len(ctx.attr.root_dir.split("/")) if ctx.attr.root_dir else 0
+        root_dir_depth = len(ctx.attr.root_dir.split("/")) if ctx.attr.root_dir and ctx.attr.root_dir != "." else 0
         effective_depth = max(0, src_pkg_depth - root_dir_depth)
         s = paths.join(s, "/".join([".." for _ in range(effective_depth)]))