commit 3558f5caaf97f4bda7c899a062a35c4c62956c5a
author Chris Mumford <cmumford@google.com> Fri May 26 06:33:03 2023 -0700
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> Fri May 26 15:23:15 2023 +0000
tree 1a44f54f0d358218d18549bb8c89549ae73f393b
parent ac897edeb16a449c6e519e13ddf3decd8a6cb763

Add show_includes GN build argument

Add a show_includes GN build argument which is used for include
file analysis. show_includes requires clang to be used and adds
the -H compile argument. This produces output that can be analyzed
to understand all header files included by the source file being
compiled. Here is a sample of the output:

```
[11/1330] clang++-14 -H <other-flags...> -c \
  ../../src/gpu/ganesh/GrAHardwareBufferImageGenerator.cpp -o \
  obj/src/gpu/ganesh/gpu.GrAHardwareBufferImageGenerator.o
. ../../include/core/SkTypes.h
.. ../../include/private/base/SkFeatures.h
.. ../../include/private/base/SkLoadUserConfig.h
... ../../include/private/base/SkFeatures.h
... ../../include/config/SkUserConfig.h
.. ../../include/private/base/SkAPI.h
... ../../include/private/base/SkLoadUserConfig.h

<many other headers>
```

Bug: skia:12159
Change-Id: Ideeb6daa9fd27cb8f5be02f358b0d1c8c5f6dc91
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/703456
Auto-Submit: Chris Mumford <cmumford@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Chris Mumford <cmumford@google.com>

gn/BUILDCONFIG.gn

diff --git a/gn/BUILDCONFIG.gn b/gn/BUILDCONFIG.gn
index 188614c..acf4a54 100644
--- a/gn/BUILDCONFIG.gn
+++ b/gn/BUILDCONFIG.gn
@@ -33,6 +33,10 @@
   ios_min_target = ""
   ios_use_simulator =
       target_os == "ios" && (target_cpu == "x86" || target_cpu == "x64")
+
+  # Enable -H, which prints the include tree during compilation.
+  # For use by external tools for analyzing include files.
+  show_includes = false
 }
 declare_args() {
   is_debug = !is_official_build

gn/skia/BUILD.gn

diff --git a/gn/skia/BUILD.gn b/gn/skia/BUILD.gn
index bed7053..c712107 100644
--- a/gn/skia/BUILD.gn
+++ b/gn/skia/BUILD.gn
@@ -180,6 +180,21 @@
     ldflags += [ "-static-libstdc++" ]
   }
 
+  if (show_includes) {
+    assert(is_clang, "show_includes requires clang to build.")
+    if (is_win) {
+      cflags += [
+        "/clang:-H",
+        "/clang:-fshow-skipped-includes",
+      ]
+    } else {
+      cflags += [
+        "-H",
+        "-fshow-skipped-includes",
+      ]
+    }
+  }
+
   if (is_ios) {
     if (target_cpu == "arm") {
       _arch_flags = [