Feat: use CMAKE_CXX_STDLIB_MODULES_JSON from preset

Author: ClausKlein

.CMakeUserPresets.json

@@ -1,8 +1,8 @@
 {
-  "version": 8,
+  "version": 9,
   "cmakeMinimumRequired": {
     "major": 3,
-    "minor": 28,
+    "minor": 30,
     "patch": 0
   },
   "configurePresets": [
@@ -32,7 +32,10 @@
       "inherits": [
         "dev-common",
         "ci-Darwin"
-      ]
+      ],
+      "cacheVariables": {
+        "CMAKE_CXX_STDLIB_MODULES_JSON": "$env{CMAKE_CXX_STDLIB_MODULES_JSON}"
+      }
     },
     {
       "name": "dev-Windows",

CMakeLists.txt

@@ -11,15 +11,15 @@ if(CMAKE_CXX_SCAN_FOR_MODULES)
     set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD
         "d0edc3af-4c50-42ea-a356-e2862fe7a444"
     )
-    if(APPLE AND $ENV{CXX} STREQUAL g++-15)
-        set(CMAKE_CXX_STDLIB_MODULES_JSON
-            /usr/local/Cellar/gcc/15.2.0/lib/gcc/current/libstdc++.modules.json
-        )
-    else()
-        set(CMAKE_CXX_STDLIB_MODULES_JSON
-            $ENV{LLVM_DIR}/lib/c++/libc++.modules.json
-        )
-    endif()
+    # if(APPLE AND $ENV{CXX} STREQUAL g++-15)
+    #     set(CMAKE_CXX_STDLIB_MODULES_JSON
+    #         $ENV{GCC_DIR}/lib/gcc/current/libstdc++.modules.json
+    #     )
+    # else()
+    #     set(CMAKE_CXX_STDLIB_MODULES_JSON
+    #         $ENV{LLVM_DIR}/lib/c++/libc++.modules.json
+    #     )
+    # endif()
 endif()
 
 #==================================================
@@ -127,7 +127,7 @@ if(CMAKE_GENERATOR STREQUAL "Ninja" AND FMT_USE_MODULES)
 
     # Tell CMake that we explicitly want `import std`.
     # This will initialize the property on all targets declared after this to 1
-    if(NOT APPLE AND 23 IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD)
+    if(${CMAKE_CXX_STANDARD} IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD)
         set(CMAKE_CXX_MODULE_STD ON)
     endif()
 

GNUmakefile

@@ -1,26 +1,35 @@
 # Standard stuff
 
 .SUFFIXES:
-$(VERBOSE).SILENT:
 
-MAKEFLAGS+= --no-builtin-rules
-MAKEFLAGS+= --warn-undefined-variables
+MAKEFLAGS+= --no-builtin-rules  # Disable the built-in implicit rules.
+# MAKEFLAGS+= --warn-undefined-variables        # Warn when an undefined variable is referenced.
+# MAKEFLAGS+= --include-dir=$(CURDIR)/conan     # Search DIRECTORY for included makefiles (*.mk).
 
 export hostSystemName=$(shell uname)
 
 ifeq (${hostSystemName},Darwin)
-  export LLVM_PREFIX:=$(shell brew --prefix llvm)
-  export LLVM_DIR?=$(shell realpath ${LLVM_PREFIX})
+  export LLVM_PREFIX=$(shell brew --prefix llvm)
+  export LLVM_DIR=$(shell realpath ${LLVM_PREFIX})
   export PATH:=${LLVM_DIR}/bin:${PATH}
-  # export CXX:=clang++
 
-  # to test g++-15:
+  # export CMAKE_CXX_STDLIB_MODULES_JSON=${LLVM_DIR}/lib/c++/libc++.modules.json
+  # export CXX=clang++
+  # export LDFLAGS=-L$(LLVM_DIR)/lib/c++ -lc++abi -lc++ -lc++experimental
+  # export GCOV="llvm-cov gcov"
+
+  ### TODO: to test g++-15:
+  export GCC_PREFIX=$(shell brew --prefix gcc)
+  export GCC_DIR=$(shell realpath ${GCC_PREFIX})
+
+  export CMAKE_CXX_STDLIB_MODULES_JSON=${GCC_DIR}/lib/gcc/current/libstdc++.modules.json
   export CXX:=g++-15
   export CXXFLAGS:=-stdlib=libstdc++
+  export GCOV="gcov"
 else ifeq (${hostSystemName},Linux)
-  export LLVM_DIR?=/usr/lib/llvm-20
+  export LLVM_DIR=/usr/lib/llvm-20
   export PATH:=${LLVM_DIR}/bin:${PATH}
-  export CXX:=clang++-20
+  export CXX=clang++-20
 endif
 
 .PHONY: all check test example format clean distclean
@@ -67,6 +76,5 @@ GNUmakefile :: ;
 *.json :: ;
 
 # Anything we don't know how to build will use this rule.
-# The command is a do-nothing command.
-#
-% :: ;
+% ::
+	ninja -C build $(@)