Pass headers along as transitive dependencies (#4298)

This fixes github.com/cloudflare/circl relative imports by making those
headers available at compile time.

**What type of PR is this?**

Feature

**What does this PR do? Why is it needed?**

Expose headers in GoArchive so that compilepkg can make them visible.
This will make it possible for relative imports to find header files.

**Which issues(s) does this PR fix?**

Fixes #4154 

**Other notes for review**

Author: patrickmscott

go/private/actions/archive.bzl

@@ -87,6 +87,11 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
     importpath, _ = effective_importpath_pkgpath(source)
 
     cgo_out_dir = None
+    headers = depset(
+        direct = [f for f in source.srcs if f.path.split(".")[-1].lower().startswith("h")],
+        transitive = [a._headers for a in direct],
+    )
+
     if source.cgo and not go.mode.pure:
         cgo_out_dir = go.declare_directory(go, path = out_lib.basename + ".cgo")
 
@@ -116,6 +121,7 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
             importpath = importpath,
             importmap = importmap,
             archives = direct,
+            headers = headers,
             out_lib = out_lib,
             out_export = out_export,
             out_facts = out_facts,
@@ -146,6 +152,7 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
             importpath = importpath,
             importmap = importmap,
             archives = direct,
+            headers = headers,
             out_lib = out_lib,
             out_export = out_export,
             out_facts = out_facts,
@@ -217,4 +224,5 @@ def emit_archive(go, source = None, _recompile_suffix = "", recompile_internal_d
         cgo_deps = depset(transitive = [cgo_deps] + [a.cgo_deps for a in direct]),
         cgo_exports = cgo_exports,
         runfiles = runfiles,
+        _headers = headers,
     )

go/private/actions/compilepkg.bzl

@@ -57,6 +57,7 @@ def emit_compilepkg(
         importpath = "",
         importmap = "",
         archives = [],
+        headers = depset(),
         cgo = False,
         cgo_inputs = depset(),
         cgo_out_dir = None,
@@ -95,7 +96,7 @@ def emit_compilepkg(
     sdk = go.sdk
     inputs_direct = (sources + embedsrcs + [sdk.package_list] +
                      [archive.data.export_file for archive in archives])
-    inputs_transitive = [sdk.headers, sdk.tools, go.stdlib.libs]
+    inputs_transitive = [sdk.headers, sdk.tools, go.stdlib.libs, headers]
     outputs = [out_lib, out_export]
 
     shared_args = go.builder_args(go, use_path_mapping = True)

go/private/rules/test.bzl

@@ -732,6 +732,7 @@ def _recompile_external_deps(go, external_go_info, internal_archive, library_lab
                 cgo_exports = depset(transitive = [a.cgo_exports for a in deps]),
                 runfiles = go_info.runfiles,
                 mode = go.mode,
+                _headers = internal_archive._headers,
             )
         label_to_archive[label] = archive
 

tests/core/transitive_headers/a/BUILD.bazel

@@ -0,0 +1,11 @@
+load("//go:def.bzl", "go_library")
+
+go_library(
+    name = "a",
+    srcs = [
+        "a.go",
+        "a.s",
+    ],
+    deps = ["//tests/core/transitive_headers/b"],
+    importpath = "github.com/bazelbuild/rules_go/tests/core/transitive_headers/a",
+)

tests/core/transitive_headers/a/a.go

@@ -0,0 +1 @@
+package a

tests/core/transitive_headers/a/a.s

@@ -0,0 +1 @@
+#include "../b/b.h"

tests/core/transitive_headers/b/BUILD.bazel

@@ -0,0 +1,12 @@
+load("//go:def.bzl", "go_library")
+
+go_library(
+    name = "b",
+    srcs = [
+        "b.go",
+        "b.h",
+    ],
+    deps = ["//tests/core/transitive_headers/c"],
+    importpath = "github.com/bazelbuild/rules_go/tests/core/transitive_headers/b",
+    visibility = ["//visibility:public"],
+)

tests/core/transitive_headers/b/b.go

@@ -0,0 +1 @@
+package b

tests/core/transitive_headers/b/b.h

@@ -0,0 +1 @@
+#include "../c/c.h"

tests/core/transitive_headers/c/BUILD.bazel

@@ -0,0 +1,11 @@
+load("//go:def.bzl", "go_library")
+
+go_library(
+    name = "c",
+    srcs = [
+        "c.go",
+        "c.h",
+    ],
+    importpath = "github.com/bazelbuild/rules_go/tests/core/transitive_headers/c",
+    visibility = ["//visibility:public"],
+)