erlang: simplify generated sources handling

Summary:
We weren't using the map result - a simple list is enough, we can also simplify the code by moving where the output path is generated (and how we generate it now that we don't have multiple toolchains).

The rejection of modules from `src` was a noop, unless there was a duplicate module - one generated and one in sources, but we should absolutely error if that is the case, rather than silently ignoring it as before.

Reviewed By: TheGeorge

Differential Revision: D81781359

fbshipit-source-id: e57765d723e40546c862697e75b4859f407d1c7b

Author: michalmuskala

erlang/erlang_application.bzl

@@ -115,18 +115,18 @@ def _build_erlang_application(ctx: AnalysisContext, name: str, toolchain: Toolch
     build_environment = erlang_build.prepare_build_environment(dep_info, include_info)
 
     # build generated inputs
-    generated_source_artifacts = erlang_build.build_steps.generated_source_artifacts(ctx, toolchain, name)
+    generated_source_artifacts = erlang_build.build_steps.generated_source_artifacts(ctx, toolchain)
 
     # Put all sources in a src folder, both for hermeticity (erlc will try to load .hrl files next to the .erl file)
     # and to ultimately put it in the app folder
-    src_dir = _link_src_dir(ctx, extra_srcs = generated_source_artifacts.values())
+    src_dir = _link_src_dir(ctx, extra_srcs = generated_source_artifacts)
 
     # collect all inputs
     src_artifacts = [
         src
         for src in ctx.attrs.srcs
-        if erlang_build.utils.is_erl(src) and erlang_build.utils.module_name(src) not in generated_source_artifacts
-    ] + generated_source_artifacts.values()
+        if erlang_build.utils.is_erl(src)
+    ] + generated_source_artifacts
 
     private_header_artifacts = [header for header in ctx.attrs.srcs if erlang_build.utils.is_hrl(header)]
 

erlang/erlang_build.bzl

@@ -26,6 +26,7 @@ load(
 _BUILD_DIR = "__build"
 _DEP_FILES_DIR = paths.join(_BUILD_DIR, "__dep_files")
 _DEP_INFO_FILE = paths.join(_DEP_FILES_DIR, "app.info.dep")
+_GENERATED_DIR = paths.join(_BUILD_DIR, "__generated")
 
 BuildEnvironment = record(
     includes = field(IncludesMapping, {}),
@@ -86,21 +87,16 @@ def _prepare_build_environment(
         beams = beams,
     )
 
-def _generated_source_artifacts(ctx: AnalysisContext, toolchain: Toolchain, name: str) -> PathArtifactMapping:
+def _generated_source_artifacts(ctx: AnalysisContext, toolchain: Toolchain) -> list[Artifact]:
     """Generate source output artifacts and build actions for generated erl files."""
 
-    def build(src, custom_include_opt):
-        return _build_xyrl(
-            ctx,
-            toolchain,
-            src,
-            custom_include_opt,
-            ctx.actions.declare_output(generated_erl_path(name, src)),
-        )
-
-    yrl_outputs = {module_name(src): build(src, "yrl_includefile") for src in ctx.attrs.srcs if _is_yrl(src)}
-    xrl_outputs = {module_name(src): build(src, "xrl_includefile") for src in ctx.attrs.srcs if _is_xrl(src)}
-    return yrl_outputs | xrl_outputs
+    results = []
+    for src in ctx.attrs.srcs:
+        if _is_yrl(src):
+            results.append(_build_xyrl(ctx, toolchain, src, "yrl_includefile"))
+        elif _is_xrl(src):
+            results.append(_build_xyrl(ctx, toolchain, src, "xrl_includefile"))
+    return results
 
 # mutates build_environment in place
 def _generate_include_artifacts(
@@ -245,9 +241,9 @@ def _build_xyrl(
         ctx: AnalysisContext,
         toolchain: Toolchain,
         xyrl: Artifact,
-        custom_include_opt: str,
-        output: Artifact) -> Artifact:
+        custom_include_opt: str) -> Artifact:
     """Generate an erl file out of an xrl or yrl input file."""
+    output = ctx.actions.declare_output(_GENERATED_DIR, "{}.erl".format(module_name(xyrl)))
     erlc = toolchain.otp_binaries.erlc
     custom_include = getattr(ctx.attrs, custom_include_opt, None)
     cmd = cmd_args(erlc)
@@ -446,14 +442,6 @@ def _preserved_opts(opts: list[str]) -> cmd_args:
     joined = cmd_args(preserved, delimiter = ", ")
     return cmd_args(joined, format = "{options, [{}]}")
 
-def generated_erl_path(appname: str, src: Artifact) -> str:
-    """The output path for generated erl files."""
-    return paths.join(
-        _BUILD_DIR,
-        "__generated_%s" % (appname,),
-        "%s.erl" % (module_name(src),),
-    )
-
 def module_name(in_file: Artifact) -> str:
     """ Returns the basename of the artifact without extension """
     end = in_file.basename.rfind(".")