使用GCC≥12编译GCC时libcpp因格式安全警告构建失败

尝试用版本≥12的GCC编译GCC源码，执行make时出现多个格式安全相关的错误，报错代码经git blame确认自2012年未修改，怀疑是构建配置遗漏。当前在Nix Shell环境下构建，相关信息如下：

错误日志 #

tti -I../../../../gittea/gcc/libcpp -I.
-I../../../../gittea/gcc/libcpp/../include
-I../../../../gittea/gcc/libcpp/include    -c -o expr.o -MT expr.o
-MMD -MP -MF .deps/expr.Tpo ../../../../gittea/gcc/libcpp/expr.cc
../../../../gittea/gcc/libcpp/expr.cc: In function ‘unsigned int
cpp_classify_number(cpp_reader*, const cpp_token*, const char**,
location_t)’:
../../../../gittea/gcc/libcpp/expr.cc:842:35: error: format not a
string literal and no format arguments [-Werror=format-security]
  842 |             cpp_warning_with_line (pfile, CPP_W_LONG_LONG,
virtual_location,
      |
~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  843 |                                    0, message);
      |                                    ~~~~~~~~~~~
../../../../gittea/gcc/libcpp/expr.cc:845:38: error: format not a
string literal and no format arguments [-Werror=format-security]
  845 |             cpp_pedwarning_with_line (pfile, CPP_W_LONG_LONG,
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
  846 |                                       virtual_location, 0, message);
      |                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../../gittea/gcc/libcpp/expr.cc:855:33: error: format not a
string literal and no format arguments [-Werror=format-security]
  855 |           cpp_warning_with_line (pfile, CPP_W_SIZE_T_LITERALS,
      |           ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  856 |                                  virtual_location, 0, message);
      |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../../gittea/gcc/libcpp/expr.cc:867:42: error: format not a
string literal and no format arguments [-Werror=format-security]
  867 |                 cpp_pedwarning_with_line (pfile, CPP_W_C11_C2X_COMPAT,
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  868 |                                           virtual_location, 0, message);
      |                                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../../gittea/gcc/libcpp/expr.cc:870:39: error: format not a
string literal and no format arguments [-Werror=format-security]
  870 |                 cpp_warning_with_line (pfile, CPP_W_C11_C2X_COMPAT,
      |                 ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  871 |                                        virtual_location, 0, message);
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../../gittea/gcc/libcpp/expr.cc:877:35: error: format not a
string literal and no format arguments [-Werror=format-security]
  877 |               cpp_error_with_line (pfile, CPP_DL_PEDWARN,
virtual_location, 0,
      |
~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  878 |                                    message);
      |                                    ~~~~~~~~
cc1plus: some warnings are being treated as errors

当前Nix Flake配置 #

{
  description = "gcc compiler";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let pkgs = nixpkgs.legacyPackages.${system};
      in {
        packages = {
          default = pkgs.gnumake;
        };
        formatter = pkgs.nixpkgs-fmt;

        devShell = pkgs.mkShell {
          buildInputs = [
            pkgs.gnumake
            pkgs.gcc13

            pkgs.libgcc
            pkgs.glibc

            pkgs.gmp
            pkgs.libmpc
            pkgs.mpfr
            pkgs.flex
            pkgs.bison

            pkgs.isl
            pkgs.pkg-config
            pkgs.autoconf-archive
            pkgs.autoconf
            pkgs.automake
          ];
        };
      }
    );
}

解决步骤 #

1. 调整GCC构建配置参数 #

高版本GCC默认开启-Wformat-security并将其转为错误，可在configure阶段禁用该规则的错误转换：

../configure --disable-werror=format-security

若需临时禁用所有警告转错误（不推荐，可能掩盖其他问题）：

../configure --disable-werror

2. 修改Nix Shell环境变量 #

在Nix Shell的mkShell中显式覆盖编译参数，禁用该错误：

devShell = pkgs.mkShell {
  buildInputs = [
    # 保留原有依赖
    pkgs.gnumake
    pkgs.gcc13
    pkgs.libgcc
    pkgs.glibc
    pkgs.gmp
    pkgs.libmpc
    pkgs.mpfr
    pkgs.flex
    pkgs.bison
    pkgs.isl
    pkgs.pkg-config
    pkgs.autoconf-archive
    pkgs.autoconf
    pkgs.automake
  ];
  # 禁用format-security的错误转换
  CFLAGS = "-Wno-error=format-security";
  CXXFLAGS = "-Wno-error=format-security";
};

3. 更换编译用的GCC版本 #

GCC官方推荐用比目标版本低一级的编译器编译自身，比如编译GCC 13时用GCC 12。可在Nix配置中将pkgs.gcc13替换为pkgs.gcc12，降低编译工具链版本以兼容旧代码。

4. 切换GCC源码分支 #

若编译的是未适配新警告规则的旧GCC分支，可切换到对应稳定分支（如gcc-13-branch），该分支代码已适配高版本编译器的警告规则。

内容的提问来源于stack exchange，提问作者vincenzopalazzo