Fix propagation of generator expressions from parent directory

.github/workflows/dev.yml

@@ -108,7 +108,8 @@ jobs:
         run: |
           echo "set man-db/auto-update false" | sudo debconf-communicate && sudo dpkg-reconfigure man-db
           sudo apt-get -qq update
-          sudo apt-get -qq install -y git build-essential cmake zlib1g-dev libbz2-dev libedit-dev
+          sudo apt-get -qq install -y git build-essential cmake zlib1g-dev libbz2-dev libedit-dev ninja-build
+
 
       - name: Checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -166,8 +167,8 @@ jobs:
           for useStaticLibs in ON OFF; do
             echo "== Testing CMake install interface with PCRE2_USE_STATIC_LIBS=$useStaticLibs =="
             rm -rf build
-            cmake $CMAKE_FLAGS -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="$INSTALL_PREFIX" -DPCRE2_USE_STATIC_LIBS=$useStaticLibs -B build
-            (cd build; make)
+            cmake -GNinja $CMAKE_FLAGS -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH="$INSTALL_PREFIX" -DPCRE2_USE_STATIC_LIBS=$useStaticLibs -B build
+            (cd build; ninja)
             ./build/test_executable
             ldd ./build/test_executable
             if [ $useStaticLibs = ON ]; then
@@ -190,8 +191,8 @@ jobs:
             shared=`echo $buildLibs | cut -d';' -f2`
             echo "== Testing CMake build interface with BUILD_STATIC_LIBS=$static and BUILD_SHARED_LIBS=$shared =="
             rm -rf build
-            cmake $CMAKE_FLAGS -DCMAKE_BUILD_TYPE=Debug -DBUILD_STATIC_LIBS=$static -DBUILD_SHARED_LIBS=$shared -B build
-            (cd build; make)
+            cmake -GNinja $CMAKE_FLAGS -DCMAKE_BUILD_TYPE=Debug -DBUILD_STATIC_LIBS=$static -DBUILD_SHARED_LIBS=$shared -B build
+            (cd build; ninja)
             ./build/test_executable
             ldd ./build/test_executable
             if [ $static = ON ]; then

CMakeLists.txt

@@ -178,14 +178,19 @@ check_include_file(windows.h HAVE_WINDOWS_H)
 pcre2_use_system_extensions()
 
 cmake_push_check_state(RESET)
-# Somewhat awkward code to propagate the _GNU_SOURCE definition (added to
-# COMPILE_DEFINITIONS by pcre2_use_system_extensions()).
+# Propagate the _GNU_SOURCE definition (added to COMPILE_DEFINITIONS by
+# pcre2_use_system_extensions()) so that these check_symbol_exists() calls
+# can find symbols only exposed with _GNU_SOURCE.
+# We only pass through known plain-text definitions (like _GNU_SOURCE) and
+# skip anything else (e.g. generator expressions inherited from a parent
+# project), because try_compile() cannot handle generator expressions.
 get_directory_property(_pcre2_compile_definitions COMPILE_DEFINITIONS)
 if(DEFINED _pcre2_compile_definitions)
   set(CMAKE_REQUIRED_DEFINITIONS "")
-  foreach(_def IN LISTS _pcre2_compile_definitions)
-    list(APPEND CMAKE_REQUIRED_DEFINITIONS "-D${_def}")
-  endforeach()
+  list(FIND _pcre2_compile_definitions "_GNU_SOURCE" _idx)
+  if(_idx GREATER -1)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS "-D_GNU_SOURCE")
+  endif()
 endif()
 
 check_symbol_exists(mkostemp stdlib.h HAVE_MKOSTEMP) # glibc 2.7

maint/cmake-tests/build-interface/CMakeLists.txt

@@ -3,6 +3,12 @@ project(TestBuildInterface C)
 set(CMAKE_C_STANDARD 99)
 set(CMAKE_C_STANDARD_REQUIRED TRUE)
 
+# We had a regression where a parent project compile definition containing
+# generator expressions was incorrectly propagated to CMAKE_REQUIRED_DEFINITIONS
+# (which doesn't support generator expressions). This dummy macro here prevents
+# that happening again.
+add_compile_definitions($<$<CONFIG:Debug>:PARENT_PROJECT_MACRO>)
+
 # To test the static vs dynamic interface, uncomment one of the following lines:
 # set(BUILD_STATIC_LIBS OFF)
 # set(BUILD_SHARED_LIBS ON)