erenon / rules_pch

Precompiled header rule for Bazel

Precompiled Header (PCH) support for Bazel + GCC

Requires GCC and Bazel 3.1. Clang support needs slight modification.

Usage

• Copy precompiled_headers.bzl to your workspace

• Create a header file that is going to be the first include in your source files, e.g: Common.hpp or stdafx.h

• Add common includes to this main header file - these are going to be precompiled

• Add a precompiled_headers rule, add cc_library dependencies that provide the header files included by the main header file:

   load("//:precompiled_headers.bzl", "precompiled_headers")
  
   precompiled_headers(
     name = "pch",
     main = "Common.hpp",
     deps = [":libA", ":libB"],
   )
  

• Depend on the created target, copts must include -fpch-deps:

   cc_binary(
     name = "app",
     copts = ["-Winvalid-pch", "-Werror", "-fpch-deps"],
     srcs = ["app.cpp"],
     deps = [":pch"],
   )
  

If -pch-deps is not specified, bazel will not rebuild app if pch changes. This is a GCC bug, see:

• https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14933
• https://bugs.openjdk.java.net/browse/JDK-7175914

Test

$ bazel build test/...

License

Public domain.