handle precompiled headers with `ccache` / fixed caching in some docker builds (#4505)

* CI-unixish.yml: handle precompiled headers with `ccache`

* actually support `ccache` in CMake < 3.17

* CI-unixish-docker.yml: split CMake build and test execution into separate steps

* findDependencies.cmake: only print message about macthcompiler being disabled when it is actually used

* CI-unixish-docker.yml: added missing `ccache` CMake options

.github/workflows/CI-unixish-docker.yml

@@ -52,7 +52,7 @@ jobs:
           key: ${{ github.workflow }}-${{ matrix.image }}
 
       # tests require CMake 3.9 - no ccache available
-      - name: Test CMake build (no tests)
+      - name: CMake build (no tests)
         if: matrix.image == 'ubuntu:14.04'
         run: |
           mkdir cmake.output
@@ -61,7 +61,7 @@ jobs:
           cmake --build . -- -j$(nproc)
 
       # tests require CMake 3.9 - ccache available
-      - name: Test CMake build (no tests)
+      - name: CMake build (no tests)
         if: matrix.image == 'centos:7' || matrix.image == 'ubuntu:16.04'
         run: |
           mkdir cmake.output
@@ -69,13 +69,18 @@ jobs:
           cmake -G "Unix Makefiles" -DHAVE_RULES=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache ..
           cmake --build . -- -j$(nproc)
 
-      - name: Test CMake build
+      - name: CMake build
         if: matrix.image != 'centos:7' && matrix.image != 'ubuntu:14.04' && matrix.image != 'ubuntu:16.04'
         run: |
           mkdir cmake.output
           cd cmake.output
-          cmake -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On ..
-          cmake --build . --target check -- -j$(nproc)
+          cmake -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache ..
+          cmake --build . -- -j$(nproc)
+
+      - name: Run CMake test
+        if: matrix.image != 'centos:7' && matrix.image != 'ubuntu:14.04' && matrix.image != 'ubuntu:16.04'
+        run: |
+          cmake --build cmake.output --target check -- -j$(nproc)
 
   build_make:
 

.github/workflows/CI-unixish.yml

@@ -17,6 +17,10 @@ jobs:
 
     runs-on: ${{ matrix.os }}
 
+    env:
+      # TODO: files are cached but are still cache misses on platforms other than ubuntu-22.04
+      CCACHE_SLOPPINESS: pch_defines,time_macros
+
     steps:
       - uses: actions/checkout@v2
 
@@ -62,6 +66,10 @@ jobs:
 
     runs-on: ${{ matrix.os }}
 
+    env:
+      # TODO: files are cached but are still cache misses
+      CCACHE_SLOPPINESS: pch_defines,time_macros
+
     steps:
       - uses: actions/checkout@v2
 

CMakeLists.txt

@@ -5,6 +5,7 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 include(GNUInstallDirs)
 
+include(cmake/ccache.cmake)
 include(cmake/compilerCheck.cmake)
 include(cmake/versions.cmake)
 include(cmake/options.cmake)

cmake/ccache.cmake

@@ -0,0 +1,7 @@
+if (CMAKE_VERSION VERSION_LESS "3.17")
+    if (CMAKE_CXX_COMPILER_LAUNCHER)
+        set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CMAKE_CXX_COMPILER_LAUNCHER}")
+    elseif (CMAKE_C_COMPILER_LAUNCHER)
+        set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CMAKE_C_COMPILER_LAUNCHER}")
+    endif()
+endif()

cmake/findDependencies.cmake

@@ -48,7 +48,7 @@ find_package(PythonInterp 3 QUIET)
 if (NOT PYTHONINTERP_FOUND)
     set(PYTHONINTERP_FOUND "")
     find_package(PythonInterp 2.7 QUIET)
-    if (NOT PYTHONINTERP_FOUND)
+    if (NOT PYTHONINTERP_FOUND AND NOT USE_MATCHCOMPILER_OPT STREQUAL "Off")
         message(WARNING "No python interpreter found. Therefore, the match compiler is switched off.")
         set(USE_MATCHCOMPILER_OPT "Off")
     endif()