fix: pass all srcs to ts_project transpilers

Fixes #219

docs/transpiler.md

@@ -20,13 +20,16 @@ Read more: https://blog.aspect.dev/typescript-speedup
 The `transpiler` attribute of `ts_project` lets you select which tool produces the JavaScript outputs. The default value of `None` means that `tsc` should do transpiling along with type-checking, as this is the simplest configuration without additional dependencies. However as noted above, it's also the slowest.
 
 The `transpiler` attribute accepts a rule or macro with this signature:
-`name, srcs, js_outs, map_outs, **kwargs`
+`name, srcs, **kwargs`
 where the `**kwargs` attribute propagates the tags, visibility, and testonly attributes from `ts_project`.
 
-If you need to pass additional attributes to the transpiler rule, you can use a
+If you need to pass additional attributes to the transpiler rule such as `out_dir`, you can use a
 [partial](https://github.com/bazelbuild/bazel-skylib/blob/main/lib/partial.bzl)
 to bind those arguments at the "make site", then pass that partial to this attribute where it will be called with the remaining arguments.
-
+The transpiler rule or macro is responsible for predicting and declaring outputs.
+If you want to pre-declare the outputs (so that they can be addressed by a Bazel label, like `//path/to:index.js`)
+then you should use a macro which calculates the predicted outputs and supplies them to a `ctx.attr.outputs` attribute
+on the rule.
 See the examples/transpiler directory for a simple example using Babel, or
 <https://github.com/aspect-build/bazel-examples/tree/main/ts_project_transpiler>
 for a more complete example that also shows usage of SWC.

examples/transpiler/babel.bzl

@@ -1,32 +1,37 @@
 "Adapter from the Babel CLI to the ts_project#transpiler interface"
 
+load("@aspect_rules_js//js:defs.bzl", "js_library")
 load("@npm//examples:@babel/cli/package_json.bzl", "bin")
 
 # buildifier: disable=function-docstring
-def babel(name, srcs, js_outs, map_outs, **kwargs):
+def babel(name, srcs, **kwargs):
     # rules_js runs under the output tree in bazel-out/[arch]/bin
     # and we additionally chdir to the examples/ folder beneath that.
     execroot = "../../../.."
 
+    outs = []
+
     # In this example we compile each file individually.
     # You might instead use a single babel_cli call to compile
     # a directory of sources into an output directory,
     # but you'll need to:
     # - make sure the input directory only contains files listed in srcs
     # - make sure the js_outs are actually created in the expected path
     for idx, src in enumerate(srcs):
+        if not src.endswith(".ts"):
+            fail("babel example transpiler only supports source .ts files")
+
+        js_out = src.replace(".ts", ".js")
+        map_out = src.replace(".ts", ".js.map")
+
         # see https://babeljs.io/docs/en/babel-cli
         args = [
             "{}/$(location {})".format(execroot, src),
             "--presets=@babel/preset-typescript",
             "--out-file",
-            "{}/$(location {})".format(execroot, js_outs[idx]),
+            "{}/$(location {})".format(execroot, js_out),
+            "--source-maps",
         ]
-        outs = [js_outs[idx]]
-
-        if len(map_outs) > 0:
-            args.append("--source-maps")
-            outs.append(map_outs[idx])
 
         bin.babel(
             name = "{}_{}".format(name, idx),
@@ -35,7 +40,15 @@ def babel(name, srcs, js_outs, map_outs, **kwargs):
                 "//examples:node_modules/@babel/preset-typescript",
             ],
             chdir = "examples",
-            outs = outs,
+            outs = [js_out, map_out],
             args = args,
             **kwargs
         )
+
+        outs.append(js_out)
+        outs.append(map_out)
+
+    js_library(
+        name = name,
+        srcs = outs,
+    )

ts/defs.bzl

@@ -298,16 +298,14 @@ def ts_project(
     typings_out_dir = declaration_dir if declaration_dir else out_dir
     tsbuildinfo_path = ts_build_info_file if ts_build_info_file else name + ".tsbuildinfo"
 
-    js_outs = _lib.calculate_js_outs(srcs, out_dir, root_dir, allow_js, preserve_jsx, emit_declaration_only)
-    map_outs = _lib.calculate_map_outs(srcs, out_dir, root_dir, source_map, preserve_jsx, emit_declaration_only)
-    typings_outs = _lib.calculate_typings_outs(srcs, typings_out_dir, root_dir, declaration, composite, allow_js)
-    typing_maps_outs = _lib.calculate_typing_maps_outs(srcs, typings_out_dir, root_dir, declaration_map, allow_js)
+    tsc_typings_outs = _lib.calculate_typings_outs(srcs, typings_out_dir, root_dir, declaration, composite, allow_js)
+    tsc_typing_maps_outs = _lib.calculate_typing_maps_outs(srcs, typings_out_dir, root_dir, declaration_map, allow_js)
 
     tsc_js_outs = []
     tsc_map_outs = []
     if not transpiler:
-        tsc_js_outs = js_outs
-        tsc_map_outs = map_outs
+        tsc_js_outs = _lib.calculate_js_outs(srcs, out_dir, root_dir, allow_js, preserve_jsx, emit_declaration_only)
+        tsc_map_outs = _lib.calculate_map_outs(srcs, out_dir, root_dir, source_map, preserve_jsx, emit_declaration_only)
         tsc_target_name = name
     else:
         # To stitch together a tree of ts_project where transpiler is a separate rule,
@@ -317,28 +315,17 @@ def ts_project(
         typecheck_target_name = "%s_typecheck" % name
         test_target_name = "%s_typecheck_test" % name
 
-        transpile_srcs = [s for s in srcs if _lib.is_ts_src(s, allow_js)]
-        if (len(transpile_srcs) != len(js_outs)):
-            fail("ERROR: illegal state: transpile_srcs has length {} but js_outs has length {}".format(
-                len(transpile_srcs),
-                len(js_outs),
-            ))
-
         if type(transpiler) == "function" or type(transpiler) == "rule":
             transpiler(
                 name = transpile_target_name,
-                srcs = transpile_srcs,
-                js_outs = js_outs,
-                map_outs = map_outs,
+                srcs = srcs,
                 **common_kwargs
             )
         elif partial.is_instance(transpiler):
             partial.call(
                 transpiler,
                 name = transpile_target_name,
-                srcs = transpile_srcs,
-                js_outs = js_outs,
-                map_outs = map_outs,
+                srcs = srcs,
                 **common_kwargs
             )
         else:
@@ -365,7 +352,7 @@ def ts_project(
             name = name,
             # Include the tsc target in srcs to pick-up both the direct & transitive declaration outputs so
             # that this js_library can be a valid dep for downstream ts_project or other rules_js derivative rules.
-            srcs = js_outs + map_outs + [tsc_target_name],
+            srcs = [transpile_target_name, tsc_target_name],
             deps = deps,
             **common_kwargs
         )
@@ -390,8 +377,8 @@ def ts_project(
         root_dir = root_dir,
         js_outs = tsc_js_outs,
         map_outs = tsc_map_outs,
-        typings_outs = typings_outs,
-        typing_maps_outs = typing_maps_outs,
+        typings_outs = tsc_typings_outs,
+        typing_maps_outs = tsc_typing_maps_outs,
         buildinfo_out = tsbuildinfo_path if composite or incremental else None,
         emit_declaration_only = emit_declaration_only,
         tsc = tsc,

ts/test/BUILD.bazel

@@ -1,6 +1,5 @@
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 load("@bazel_skylib//rules:write_file.bzl", "write_file")
-
 load(":mock_transpiler.bzl", "mock")
 load(":transpiler_tests.bzl", "transpiler_test_suite")
 load("//ts:defs.bzl", "ts_project")
@@ -52,6 +51,15 @@ ts_project(
     tsconfig = _TSCONFIG,
 )
 
+# Ensure the output files are predeclared
+build_test(
+    name = "out_refs_test",
+    targets = [
+        "big.js",
+        "big.d.ts",
+    ],
+)
+
 # This target proves that transpilation doesn't require typechecking:
 #
 # $ bazel build examples/swc:transpile_with_typeerror
@@ -98,7 +106,7 @@ transpiler_test_suite()
 ts_project(
     name = "rootdir_works_with_repeated_directory",
     srcs = ["root/deep/root/deep_src.ts"],
+    root_dir = "root",
     transpiler = mock,
     tsconfig = _TSCONFIG,
-    root_dir = "root",
-)
+)

ts/test/mock_transpiler.bzl

@@ -1,26 +1,68 @@
 "Fixture to demonstrate a custom transpiler for ts_project"
 
-load("@bazel_skylib//rules:copy_file.bzl", "copy_file")
-load("@bazel_skylib//rules:write_file.bzl", "write_file")
-
 _DUMMY_SOURCEMAP = """{"version":3,"sources":["%s"],"mappings":"AAAO,KAAK,CAAC","file":"in.js","sourcesContent":["fake"]}"""
 
-def mock(name, srcs, js_outs, map_outs, **kwargs):
-    """Mock transpiler macro.
+def _mock_impl(ctx):
+    src_files = [src for src in ctx.files.srcs if src.short_path.endswith(".ts") and not src.short_path.endswith(".d.ts")]
+    out_files = []
+
+    for src in src_files:
+        out_path = src.short_path[len(ctx.attr.pkg_dir) + 1:] if src.short_path.startswith(ctx.attr.pkg_dir) else src.short_path
+
+        js_file = ctx.actions.declare_file(out_path.replace(".ts", ".js"))
+        map_file = ctx.actions.declare_file(out_path.replace(".ts", ".js.map"))
 
-    In real usage you would wrap a rule like
-    https://github.com/aspect-build/rules_swc/blob/main/docs/swc.md
-    """
+        out_files.append(js_file)
+        out_files.append(map_file)
 
-    for i, s in enumerate(srcs):
-        copy_file(
-            name = "_{}_{}_js".format(name, s),
-            src = s,
-            out = js_outs[i],
+        ctx.actions.run_shell(
+            inputs = [src],
+            outputs = [js_file],
+            command = "cp $@",
+            arguments = [src.path, js_file.path.replace(".ts", ".js")],
         )
 
-        write_file(
-            name = "_{}_{}_map".format(name, s),
-            out = map_outs[i],
-            content = [_DUMMY_SOURCEMAP % s],
+        ctx.actions.write(
+            output = map_file,
+            content = _DUMMY_SOURCEMAP % src.short_path,
         )
+
+    return DefaultInfo(files = depset(out_files))
+
+mock_impl = rule(
+    attrs = {
+        "srcs": attr.label_list(
+            doc = "TypeScript source files",
+            allow_files = True,
+            mandatory = True,
+        ),
+
+        # Used only to predeclare outputs
+        "outs": attr.output_list(),
+
+        # TODO: why is this needed?
+        "pkg_dir": attr.string(),
+    },
+    implementation = _mock_impl,
+)
+
+def mock(name, srcs, source_map = False, **kwargs):
+    # Calculate pre-declared outputs so they can be referenced as targets.
+    # This is an optional transpiler feature aligning with the default tsc transpiler.
+    js_outs = [
+        src.replace(".ts", ".js")
+        for src in srcs
+        if (src.endswith(".ts") and not src.endswith(".d.ts"))
+    ]
+    map_outs = [js.replace(".js", ".js.map") for js in js_outs] if source_map else []
+
+    # Run the rule producing those pre-declared outputs as well as any other outputs
+    # which can not be determined ahead of time such as within directories, goruped
+    # within a filegroup() etc.
+    mock_impl(
+        name = name,
+        srcs = srcs,
+        outs = js_outs + map_outs,
+        pkg_dir = native.package_name(),
+        **kwargs
+    )