c++ - 系统 libc 文件的 Clang 工具链失败

Question

我为 Clang 编写了一个自定义 (cc_) 工具链。经过一些来回，我现在大部分时间都在工作。然而，它失败了:

undeclared inclusion(s) in rule '//foo:foo'
this rule is missing dependency declarations for the following files included by 'foo/foobar.cpp':
  '/usr/include/features.h'
  '/usr/include/stdc-predef.h'
  '/usr/include/x86_64-linux-gnu/sys/cdefs.h'
  '/usr/include/x86_64-linux-gnu/bits/wordsize.h'
  '/usr/include/x86_64-linux-gnu/gnu/stubs.h'
  '/usr/include/x86_64-linux-gnu/gnu/stubs-64.h'
  '/usr/include/stdint.h'
  '/usr/include/x86_64-linux-gnu/bits/wchar.h'
  '/usr/include/stdio.h'
  '/usr/include/x86_64-linux-gnu/bits/types.h'
  '/usr/include/x86_64-linux-gnu/bits/typesizes.h'
  '/usr/include/libio.h'
  '/usr/include/_G_config.h'
  '/usr/include/wchar.h'
  '/usr/include/x86_64-linux-gnu/bits/stdio_lim.h'
  '/usr/include/x86_64-linux-gnu/bits/sys_errlist.h'
  '/usr/include/math.h'
  '/usr/include/x86_64-linux-gnu/bits/math-vector.h'
  '/usr/include/x86_64-linux-gnu/bits/libm-simd-decl-stubs.h'
  '/usr/include/x86_64-linux-gnu/bits/huge_val.h'
  '/usr/include/x86_64-linux-gnu/bits/huge_valf.h'
  '/usr/include/x86_64-linux-gnu/bits/huge_vall.h'
  '/usr/include/x86_64-linux-gnu/bits/inf.h'
  '/usr/include/x86_64-linux-gnu/bits/nan.h'
  '/usr/include/x86_64-linux-gnu/bits/mathdef.h'
  '/usr/include/x86_64-linux-gnu/bits/mathcalls.h'
  '/usr/include/assert.h'
  '/usr/include/string.h'
  '/usr/include/xlocale.h'

那么应该如何处理这些文件呢？简单地为工具链硬编码这些？或者是否有一个开关可以忽略系统的依赖性(/usr)？或者更确切地说，使用像 musl、newlib 或 bionic 这样的密封 libc。

编辑:

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有关实际工具链的更多详细信息，请参阅:https://github.com/abergmeier/bazel_toolchains

Answer 1

您需要将编译器的内置包含路径放入 crosstool 原型(prototype)的 cxx_builtin_include_directory 字段中，以便 Bazel 知道在包含依赖项验证期间忽略它们。您可以通过运行类似的命令来查看 gcc 兼容编译器的内置包含路径

$ $CC -x c++ -v - -c -o /dev/null < /dev/null

并寻找类似的输出

#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/7
 /usr/include/x86_64-linux-gnu/c++/7
 /usr/include/c++/7/backward
 /usr/lib/gcc/x86_64-linux-gnu/7/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include