remove std + fmt

Author: Neargye

.github/workflows/install.yaml

@@ -67,7 +67,7 @@ jobs:
           repository: fmtlib/fmt
           path: fmt-src
 
-      - name: Install toolchain
+      - name: Install toolchain and fmt
         run: |
           brew install gcc ninja
           python3 -m pip install cmake==4.4.0 --break-system-packages
@@ -76,6 +76,7 @@ jobs:
             -DCMAKE_CXX_COMPILER="${CXX}" \
             -DCMAKE_CXX_STANDARD=20 \
             -DCMAKE_CXX_STANDARD_REQUIRED=ON \
+            -DCMAKE_CXX_SCAN_FOR_MODULES=OFF \
             -DCMAKE_INSTALL_PREFIX="${RUNNER_TEMP}/fmt" \
             -DBUILD_SHARED_LIBS=OFF \
             -DFMT_DOC=OFF \

.github/workflows/ubuntu.yml

@@ -117,11 +117,9 @@ jobs:
       if: ${{ matrix.compiler.import_std == 'TRUE' }}
       run: |
         cxx_standard=23
-        fmt_integration=OFF
         stdlib_options=(-DCMAKE_CXX_FLAGS:STRING=-stdlib=libc++)
         if [[ "${{ matrix.compiler.cc }}" == gcc-* ]]; then
           cxx_standard=26
-          fmt_integration=ON
           stdlib_options=(-DCMAKE_CXX_STDLIB_MODULES_JSON="$("${CXX}" -print-file-name=libstdc++.modules.json)")
         fi
 
@@ -133,7 +131,7 @@ jobs:
           -DCMAKE_CXX_EXTENSIONS=OFF \
           -DMAGIC_ENUM_USE_MODULES:BOOL=TRUE \
           -DMAGIC_ENUM_MODULE_IMPORT_STD:BOOL=TRUE \
-          -DMAGIC_ENUM_MODULE_WITH_FMT:BOOL="${fmt_integration}" \
+          -DMAGIC_ENUM_MODULE_WITH_FMT:BOOL=FALSE \
           -GNinja \
           "${stdlib_options[@]}"
 

CMakeLists.txt

@@ -39,13 +39,16 @@ unset(MAGIC_ENUM_VERIFY_INTERFACE_HEADER_SETS_DEFAULT)
 option(MAGIC_ENUM_USE_MODULES "Build the magic_enum C++20 module target" OFF)
 option(MAGIC_ENUM_MODULE_IMPORT_STD "Build the module target with import std" OFF)
 set(MAGIC_ENUM_MODULE_WITH_FMT_DEFAULT OFF)
-if(MAGIC_ENUM_USE_MODULES AND (TARGET fmt::fmt-module OR TARGET fmt::fmt))
+if(MAGIC_ENUM_USE_MODULES AND NOT MAGIC_ENUM_MODULE_IMPORT_STD AND (TARGET fmt::fmt-module OR TARGET fmt::fmt))
   set(MAGIC_ENUM_MODULE_WITH_FMT_DEFAULT ON)
 endif()
 option(MAGIC_ENUM_MODULE_WITH_FMT "Build the module target with fmt integration" ${MAGIC_ENUM_MODULE_WITH_FMT_DEFAULT})
 unset(MAGIC_ENUM_MODULE_WITH_FMT_DEFAULT)
 option(MAGIC_ENUM_OPT_INSTALL_PACKAGE_XML "Include package.xml when installing" ${MAGIC_ENUM_OPT_INSTALL})
 
+if(MAGIC_ENUM_MODULE_IMPORT_STD AND MAGIC_ENUM_MODULE_WITH_FMT)
+  message(FATAL_ERROR "MAGIC_ENUM_MODULE_IMPORT_STD and MAGIC_ENUM_MODULE_WITH_FMT cannot be enabled together; use std::format with import std")
+endif()
 if(MAGIC_ENUM_MODULE_IMPORT_STD AND NOT MAGIC_ENUM_USE_MODULES)
   message(FATAL_ERROR "MAGIC_ENUM_MODULE_IMPORT_STD requires MAGIC_ENUM_USE_MODULES=ON")
 endif()
@@ -159,17 +162,18 @@ function(magic_enum_make_module_library name)
   )
   target_link_libraries(${name} PUBLIC ${PROJECT_NAME})
   target_compile_features(${name} PUBLIC cxx_std_${MAGIC_ENUM_MODULE_CXX_STANDARD})
-  if(ARGN)
+  if(ARGC GREATER 1)
     # Optional private definitions build test variants with custom magic_enum configurations.
     target_compile_definitions(${name} PRIVATE ${ARGN})
   endif()
 
   # Module-only definitions stay private; CMake exports them for installed module sources without propagating them to importers.
   if(MAGIC_ENUM_MODULE_FMT_TARGET)
     target_link_libraries(${name} PUBLIC ${MAGIC_ENUM_MODULE_FMT_TARGET})
-    target_compile_definitions(${name} PRIVATE MAGIC_ENUM_MODULE_WITH_FMT)
     if(MAGIC_ENUM_MODULE_USES_FMT_MODULE)
       target_compile_definitions(${name} PRIVATE MAGIC_ENUM_USE_FMT_MODULE)
+    else()
+      target_compile_definitions(${name} PRIVATE MAGIC_ENUM_USE_FMT_HEADER)
     endif()
   endif()
 

README.md

@@ -362,8 +362,8 @@ Header-only C++17 library provides static reflection for enums, work with any en
   Do not use `#include <magic_enum/...>` and `import magic_enum;` in the same program. Use the same compiler, standard library, and C++ standard when building and consuming an installed module. The pkg-config package supports only the header-only target.
 
   Optional settings:
-  - `{fmt}` support is enabled automatically when `fmt::fmt-module` or `fmt::fmt` already exists. The module target is preferred when it uses the same C++ standard. Set `MAGIC_ENUM_MODULE_WITH_FMT=ON` to require `{fmt}`, or `OFF` to disable it.
-  - Set `MAGIC_ENUM_MODULE_IMPORT_STD=ON` to enable experimental `import std` support. This requires a compatible CMake toolchain.
+  - `{fmt}` support is enabled automatically when `fmt::fmt-module` or `fmt::fmt` already exists and `import std` is disabled. The module target is preferred when it uses the same C++ standard. Set `MAGIC_ENUM_MODULE_WITH_FMT=ON` to require `{fmt}`, or `OFF` to disable it.
+  - Set `MAGIC_ENUM_MODULE_IMPORT_STD=ON` to enable experimental `import std` support. Use `std::format` in this mode. `{fmt}` integration cannot be enabled. This requires a compatible CMake toolchain.
 
 ## Header-only compiler compatibility
 

module/magic_enum.cppm

@@ -1,7 +1,7 @@
 module;
 
 #include <version>
-#if defined(MAGIC_ENUM_MODULE_WITH_FMT) && !defined(MAGIC_ENUM_USE_FMT_MODULE)
+#ifdef MAGIC_ENUM_USE_FMT_HEADER
 #  include <fmt/format.h>
 #endif
 
@@ -203,7 +203,7 @@ namespace detail {
 #endif
 }
 
-#if defined(MAGIC_ENUM_MODULE_WITH_FMT) && !defined(MAGIC_ENUM_USE_FMT_MODULE)
+#ifdef MAGIC_ENUM_USE_FMT_HEADER
 export namespace fmt {
   using fmt::formatter;
 }

test/installed_module/main.cpp

@@ -3,7 +3,6 @@
 
 #include <version>
 
-// Include fmt before import std to avoid duplicate standard-library declarations with GCC modules.
 #if defined(MAGIC_ENUM_TEST_FMT) && !defined(MAGIC_ENUM_TEST_FMT_MODULE)
 #  include <fmt/format.h>
 #endif