feat: add fmt 12.2.0 as C++23 module package (import fmt;) by 1115040131 · Pull Request #63 · mcpplibs/mcpp-index

1115040131 · 2026-07-07T09:51:58Z

概述

新增公开的 fmt 包(空命名空间),将 {fmt} 12.2.0 以 C++23 模块形态收录,
用户可直接 import fmt;。它是 header 版 compat.fmt 的模块孪生包,两者
消费模型不同、可共存。

形态:module wrapper(generated_files)

fmt 的 release 自带官方模块单元 src/fmt.cc(export module fmt;),但不能
逐字喂给 mcpp:mcpp 的 M1 模块扫描器拒绝任何位于条件预处理块内的 import
(即使是不启用的死分支),而 fmt.cc 把 import std; 包在 #ifdef FMT_IMPORT_STD
里。该限制在 mcpp 0.0.81 / 0.0.82 / main 均存在,非版本问题。

因此描述符用 generated_files 复刻 fmt.cc,仅删除那 3 行(#ifdef /
import std; / #endif),其余逐字保留:

全局模块片段的 #include(std 头挂到全局模块)
export module fmt;(mcpp 据此注册 provider)
FMT_EXPORT 宏机制(fmt 头文件在 FMT_MODULE 下自行 export)
末尾 #include "format.cc" / "os.cc"(把实现附着到模块 fmt;若作为独立 TU
编译会留在全局模块,破坏模块链接)

include_dirs 暴露 */include(模块单元的 #include <fmt/*.h> 可解析)与
*/src(末尾 impl include 可解析)。import_std = false(默认走文本 std 头)。

CI

空命名空间包无法作为 workspace 成员(同公开的 imgui 包:空命名空间映射到
mcpp 内建默认索引,[indices] 无法把默认索引重定向到本地 path)。故新增
tests/smoke_fmt_module.sh —— reseed 默认索引后消费 import fmt;,在
validate.yml 中作为 fmt-module job 运行(与 imgui-module 同构)。

镜像

无 mcpp-res 写权限,下载 url 采用纯上游字符串(lint 对纯字符串 url 放行),
CN 镜像待维护者后续补充。

验证

mcpp 0.0.81(与 CI MCPP_VERSION 一致)本地跑 smoke:构建模块 fmt 并通过
行为断言。

Compiling fmt v12.2.0
Finished release [optimized]
Running target/.../bin/fmt-module-smoke
fmt module package ok: 2 + 3 = 5

本地复现 CI lint 全过,validate.yml YAML 校验通过。

Module sibling of the header-based compat.fmt: the public `fmt` package (empty namespace) exposes the C++23 module `fmt` so users write `import fmt;`. fmt's release ships an official module unit at src/fmt.cc, but mcpp's M1 scanner rejects any `import` inside a conditional preprocessor block (even a dead one), and fmt.cc guards `import std;` behind `#ifdef FMT_IMPORT_STD`. So the descriptor reproduces fmt.cc via generated_files with exactly those three lines removed — everything else verbatim, including the tail `#include "format.cc"/"os.cc"` that attaches the implementation to module fmt. include_dirs exposes */include and */src so both the module unit and its impl includes resolve. Empty-namespace packages can't be workspace members (like the imgui module package), so a thin driver tests/smoke_fmt_module.sh reseeds the default index and consumes `import fmt;`, wired into validate.yml as the fmt-module job. Verified locally on mcpp 0.0.81 (== CI): the smoke builds module fmt and its behavioral assertions pass. No mcpp-res write access, so the download url is a plain upstream string (CN mirror to be added by a maintainer). Co-Authored-By: Claude <noreply@anthropic.com>

Sunrisepeak · 2026-07-07T19:16:13Z

+  # thin driver that reseeds the default index and consumes `import fmt;`.
+  fmt-module:
+    runs-on: ubuntu-latest
+    timeout-minutes: 60


不用加这个

Sunrisepeak · 2026-07-07T19:18:59Z

+        modules      = { "fmt" },
+        include_dirs = { "*/include", "*/src" },
+        generated_files = {
+            ["mcpp_generated/fmt_module.cc"] = "// Formatting library for C++ - C++20 module\n//\n// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors\n// All rights reserved.\n//\n// For the license information refer to format.h.\n\nmodule;\n\n#define FMT_MODULE\n\n#ifdef _MSVC_LANG\n#  define FMT_CPLUSPLUS _MSVC_LANG\n#else\n#  define FMT_CPLUSPLUS __cplusplus\n#endif\n\n// Put all implementation-provided headers into the global module fragment\n// to prevent attachment to this module.\n#ifndef FMT_IMPORT_STD\n#  include <algorithm>\n#  include <bitset>\n#  include <chrono>\n#  include <cmath>\n#  include <complex>\n#  include <cstddef>\n#  include <cstdint>\n#  include <cstdio>\n#  include <cstdlib>\n#  include <cstring>\n#  include <ctime>\n#  include <exception>\n#  if FMT_CPLUSPLUS > 202002L\n#    include <expected>\n#  endif\n#  include <filesystem>\n#  include <fstream>\n#  include <functional>\n#  include <iterator>\n#  include <limits>\n#  include <locale>\n#  include <memory>\n#  include <optional>\n#  include <ostream>\n#  include <source_location>\n#  include <stdexcept>\n#  include <string>\n#  include <string_view>\n#  include <system_error>\n#  include <thread>\n#  include <type_traits>\n#  include <typeinfo>\n#  include <utility>\n#  include <variant>\n#  include <vector>\n#else\n#  include <limits.h>\n#  include <stdint.h>\n#  include <stdio.h>\n#  include <stdlib.h>\n#  include <string.h>\n#  include <time.h>\n#endif\n#include <cerrno>\n#include <climits>\n#include <version>\n\n#if __has_include(<cxxabi.h>)\n#  include <cxxabi.h>\n#endif\n#if defined(_MSC_VER) || defined(__MINGW32__)\n#  include <intrin.h>\n#endif\n#if defined __APPLE__ || defined(__FreeBSD__)\n#  include <xlocale.h>\n#endif\n#if __has_include(<winapifamily.h>)\n#  include <winapifamily.h>\n#endif\n#if (__has_include(<fcntl.h>) || defined(__APPLE__) || \\\n     defined(__linux__)) &&                            \\\n    (!defined(WINAPI_FAMILY) || (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))\n#  include <fcntl.h>\n#  include <sys/stat.h>\n#  include <sys/types.h>\n#  ifndef _WIN32\n#    include <unistd.h>\n#  else\n#    include <io.h>\n#  endif\n#endif\n#ifdef _WIN32\n#  if defined(__GLIBCXX__)\n#    include <ext/stdio_filebuf.h>\n#    include <ext/stdio_sync_filebuf.h>\n#  endif\n#  define WIN32_LEAN_AND_MEAN\n#  include <windows.h>\n#endif\n\nexport module fmt;\n\n\n#define FMT_EXPORT export\n#define FMT_BEGIN_EXPORT export {\n#define FMT_END_EXPORT }\n\n// If you define FMT_ATTACH_TO_GLOBAL_MODULE\n//  - all declarations are detached from module 'fmt'\n//  - the module behaves like a traditional static library, too\n//  - all library symbols are mangled traditionally\n//  - you can mix TUs with either importing or #including the {fmt} API\n#ifdef FMT_ATTACH_TO_GLOBAL_MODULE\nextern \"C++\" {\n#endif\n\n#ifndef FMT_OS\n#  define FMT_OS 1\n#endif\n\n// All library-provided declarations and definitions must be in the module\n// purview to be exported.\n#include \"fmt/args.h\"\n#include \"fmt/chrono.h\"\n#include \"fmt/color.h\"\n#include \"fmt/compile.h\"\n#include \"fmt/format.h\"\n#if FMT_OS\n#  include \"fmt/os.h\"\n#endif\n#include \"fmt/ostream.h\"\n#include \"fmt/printf.h\"\n#include \"fmt/ranges.h\"\n#include \"fmt/std.h\"\n#include \"fmt/xchar.h\"\n\n#ifdef FMT_ATTACH_TO_GLOBAL_MODULE\n}\n#endif\n\n#ifdef FMT_ATTACH_TO_GLOBAL_MODULE\nextern \"C++\" {\n#endif\n\n#if FMT_HAS_INCLUDE(\"format.cc\")\n#  include \"format.cc\"\n#endif\n#if FMT_OS && FMT_HAS_INCLUDE(\"os.cc\")\n#  include \"os.cc\"\n#endif\n\n#ifdef FMT_ATTACH_TO_GLOBAL_MODULE\n}\n#endif\n",


这个可以使用多行语法展开不用使用 \n 放到单行。类似下面

generated_files = { ["mcpp_generated/nlohmann.json.cppm"] = [[ // L1 // L2 // .... ]], },

Sunrisepeak · 2026-07-07T19:19:48Z

+if [[ -z "$MCPP_BIN" || ! -x "$MCPP_BIN" ]]; then
+    echo "FATAL: set MCPP=/path/to/mcpp or put mcpp on PATH" >&2
+    exit 1
+fi


这个老式的ci方式已经废弃可以不用添加

Sunrisepeak · 2026-07-07T19:20:39Z

+-- (no glob), like nlohmann.json / compat.eigen.
+package = {
+    spec        = "1",
+    namespace   = "",


这个可以加上作者名或 org 名作为命名空间

Sunrisepeak · 2026-07-07T19:22:39Z

这个62PR 很规范, 建议本PR直接作为支持模块化的 fmt 库然后添加类似 62的 tests 最小测试工程。就可以省略 62 compat 模式了

feat: add compat.fmt 12.2.0 (C++ source compat) #62

Sunrisepeak · 2026-07-07T19:38:47Z

最新版本好像默认就是支持模块化的不用额外使用 generated_files 好像

https://github.com/fmtlib/fmt/blob/1be298e1bd68957e4cd352e1f676f00e07dcfb57/src/fmt.cc

Sunrisepeak · 2026-07-07T19:40:34Z

#ifdef FMT_IMPORT_STD 包描述文件直接定义这个宏就可以了

Sunrisepeak requested changes Jul 7, 2026

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Sunrisepeak mentioned this pull request Jul 7, 2026

feat: add compat.fmt 12.2.0 (C++ source compat) #62

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feat: add fmt 12.2.0 as C++23 module package (import fmt;)#63

feat: add fmt 12.2.0 as C++23 module package (import fmt;)#63
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1115040131 commented Jul 7, 2026 •

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概述

形态:module wrapper(generated_files)

CI

镜像

验证

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1115040131 commented Jul 7, 2026 •

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