Make create_closure_js_library work on providers. (#607)

This follows a more common provider approach where rules are
responsible for providing supplier to helper functions vs. helper
functions trying make it workaround with a mix of targets and
providers.

This also unbundles provider extraction from unfurl to remove
implicit and optional behaviors behind it.

closure/compiler/closure_js_binary.bzl

@@ -26,6 +26,7 @@ load(
     "collect_js",
     "collect_runfiles",
     "difference",
+    "extract_providers",
     "find_js_module_roots",
     "get_jsfile_path",
     "sort_roots",
@@ -81,8 +82,8 @@ def _impl(ctx):
             ", ".join(JS_LANGUAGES.to_list()),
         ))
 
-    deps = unfurl(ctx.attr.deps, provider = ClosureJsLibraryInfo)
-    js = collect_js(deps, ctx.attr._closure_library_base, css = ctx.attr.css)
+    deps = extract_providers(ctx.attr.deps, ClosureJsLibraryInfo)
+    js = collect_js(unfurl(deps), css = ctx.attr.css)
     if not js.srcs:
         fail("There are no JS source files in the transitive closure")
 

closure/compiler/closure_js_library.bzl

@@ -24,6 +24,7 @@ load(
     "collect_js",
     "collect_runfiles",
     "convert_path_to_es6_module_name",
+    "extract_providers",
     "find_js_module_roots",
     "get_jsfile_path",
     "library_level_checks",
@@ -100,6 +101,8 @@ def _closure_js_library_impl(
         convention,
         includes = (),
         exports = depset(),
+        deps_stylesheets = [],
+        exports_stylesheets = [],
         internal_descriptors = depset(),
         no_closure_library = False,
         internal_expect_failure = False,
@@ -121,7 +124,7 @@ def _closure_js_library_impl(
     ):
         fail("Closure toolchain undefined; rule should include CLOSURE_JS_TOOLCHAIN_ATTRS")
 
-    closure_library_base = ctx.attr._closure_library_base
+    closure_library_base = extract_providers(ctx.attr._closure_library_base, ClosureJsLibraryInfo)
     closure_worker = ctx.executable._ClosureWorker
     unusable_type_definition = ctx.files._unusable_type_definition
     actions = ctx.actions
@@ -165,7 +168,7 @@ def _closure_js_library_impl(
 
     # Create a list of direct children of this rule. If any direct dependencies
     # have the exports attribute, those labels become direct dependencies here.
-    deps = unfurl(deps, provider = ClosureJsLibraryInfo)
+    deps = unfurl(deps)
 
     # Collect all the transitive stuff the child rules have propagated. Bazel has
     # a special nested set data structure that makes this efficient.
@@ -178,9 +181,8 @@ def _closure_js_library_impl(
     # JS binary is compiled, we'll make sure it's linked against a CSS binary
     # which is a superset of the CSS libraries in its transitive closure.
     stylesheets = []
-    for dep in deps:
-        if ClosureCssLibraryInfo in dep:
-            stylesheets.append(dep.label)
+    for dep in deps_stylesheets:
+        stylesheets.append(dep.label)
 
     # JsChecker is a program that's run via the ClosureWorker persistent Bazel
     # worker. This program is a modded version of the Closure Compiler. It does
@@ -265,7 +267,7 @@ def _closure_js_library_impl(
     info_files = []
     for dep in deps:
         # Polymorphic rules, e.g. closure_css_library, might not provide this.
-        info = getattr(dep[ClosureJsLibraryInfo], "info", None)
+        info = getattr(dep, "info", None)
         if info:
             args.add("--dep", info)
             info_files.append(info)
@@ -386,13 +388,15 @@ def _closure_js_library(ctx):
     library = _closure_js_library_impl(
         ctx,
         srcs,
-        ctx.attr.deps,
+        extract_providers(ctx.attr.deps, ClosureJsLibraryInfo),
         ctx.attr.testonly,
         ctx.attr.suppress,
         ctx.attr.lenient,
         ctx.attr.convention,
         getattr(ctx.attr, "includes", []),
-        ctx.attr.exports,
+        extract_providers(ctx.attr.exports, ClosureJsLibraryInfo),
+        extract_providers(ctx.attr.deps, ClosureCssLibraryInfo),
+        extract_providers(ctx.attr.exports, ClosureCssLibraryInfo),
         ctx.files.internal_descriptors,
         ctx.attr.no_closure_library,
         ctx.attr.internal_expect_failure,
@@ -409,7 +413,7 @@ def _closure_js_library(ctx):
         DefaultInfo(
             files = depset(),
             # The usual suspects are exported as runfiles, in addition to raw source.
-           runfiles = collect_runfiles(
+            runfiles = collect_runfiles(
                 ctx,
                 files = ctx.files.srcs,
                 extra_runfiles_attrs = ["exports"],

closure/private/defs.bzl

@@ -112,6 +112,7 @@ ClosureJsBinaryInfo = provider("ClosureJsBinaryInfo", fields = ["bin", "map", "l
 ClosureCssBinaryInfo = provider("ClosureCssBinaryInfo", fields = ["bin", "map", "renaming_map", "labels"])
 
 ClosureCssLibraryInfo = provider("ClosureCssLibraryInfo", fields = [
+    "label",
     "srcs",
     "labels",
     "transitive",
@@ -131,16 +132,17 @@ def get_jsfile_path(f):
     # TODO(tjgq): Remove .zip once J2CL is switched to tree artifacts.
     return f.path if f.extension in ["js", "zip"] else None
 
+def extract_providers(deps, provider):
+    return [dep[provider] for dep in deps if provider in dep]
+
 def unfurl(deps, provider = ""):
     """Returns deps as well as deps exported by parent rules."""
     res = []
     for dep in deps:
-        if not provider or provider in dep:
-            res.append(dep)
-        if type(provider) == "Provider" and provider in dep and hasattr(dep[provider], "exports"):
-            for edep in dep[provider].exports:
-                if not provider or provider in edep:
-                    res.append(edep)
+        res.append(dep)
+        if hasattr(dep, "exports"):
+            for edep in dep.exports:
+                res.append(edep)
     return res
 
 def collect_js(
@@ -159,16 +161,16 @@ def collect_js(
     js_module_roots = []
     has_closure_library = False
     for dep in deps:
-        srcs += [getattr(dep[ClosureJsLibraryInfo], "srcs", depset())]
-        ijs_files += [getattr(dep[ClosureJsLibraryInfo], "ijs_files", depset())]
-        infos += [getattr(dep[ClosureJsLibraryInfo], "infos", depset())]
-        modules += [getattr(dep[ClosureJsLibraryInfo], "modules", depset())]
-        descriptors += [getattr(dep[ClosureJsLibraryInfo], "descriptors", depset())]
-        stylesheets += [getattr(dep[ClosureJsLibraryInfo], "stylesheets", depset())]
-        js_module_roots += [getattr(dep[ClosureJsLibraryInfo], "js_module_roots", depset())]
+        srcs += [getattr(dep, "srcs", depset())]
+        ijs_files += [getattr(dep, "ijs_files", depset())]
+        infos += [getattr(dep, "infos", depset())]
+        modules += [getattr(dep, "modules", depset())]
+        descriptors += [getattr(dep, "descriptors", depset())]
+        stylesheets += [getattr(dep, "stylesheets", depset())]
+        js_module_roots += [getattr(dep, "js_module_roots", depset())]
         has_closure_library = (
             has_closure_library or
-            getattr(dep[ClosureJsLibraryInfo], "has_closure_library", False)
+            getattr(dep, "has_closure_library", False)
         )
     if no_closure_library:
         if has_closure_library:

closure/protobuf/closure_proto_library.bzl

@@ -17,7 +17,7 @@
 
 load("@rules_proto//proto:defs.bzl", "ProtoInfo")
 load("//closure/compiler:closure_js_library.bzl", "create_closure_js_library")
-load("//closure/private:defs.bzl", "CLOSURE_JS_TOOLCHAIN_ATTRS", "ClosureJsLibraryInfo", "unfurl")
+load("//closure/private:defs.bzl", "CLOSURE_JS_TOOLCHAIN_ATTRS", "ClosureJsLibraryInfo", "extract_providers")
 
 def _generate_closure_js_progress_message(name):
     # TODO(yannic): Add a better message?
@@ -61,8 +61,8 @@ def _closure_proto_aspect_impl(target, ctx):
     js = _generate_closure_js(target, ctx)
 
     srcs = depset([js])
-    deps = unfurl(ctx.rule.attr.deps, provider = ClosureJsLibraryInfo)
-    deps += [ctx.attr._closure_library, ctx.attr._closure_protobuf_jspb]
+    deps = ctx.rule.attr.deps + [ctx.attr._closure_library, ctx.attr._closure_protobuf_jspb]
+    deps = extract_providers(deps, ClosureJsLibraryInfo)
 
     suppress = [
         "missingProperties",

closure/stylesheets/closure_css_library.bzl

@@ -29,6 +29,7 @@ def _closure_css_library(ctx):
     css = collect_css(deps, ctx.attr.orientation)
     return [
         ClosureCssLibraryInfo(
+            label = ctx.label,
             srcs = depset(ctx.files.srcs, transitive = [css.srcs]),
             labels = depset([ctx.label], transitive = [css.labels]),
             orientation = ctx.attr.orientation,