ci: Make ccache optional

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21781>

.gitlab-ci/build/g++-link-werror.sh

@@ -0,0 +1,15 @@
+#!/bin/sh -e
+
+if [ "$(ps -p $(ps -p $PPID -o ppid --no-headers) -o comm --no-headers)" != ninja ]; then
+    # Not invoked by ninja (e.g. for a meson feature check)
+    exec g++ "$@"
+fi
+
+if [ "$(eval printf "'%s'" "\"\${$(($#-1))}\"")" = "-c" ]; then
+    # Not invoked for linking
+    exec g++ "$@"
+fi
+
+# Compiler invoked by ninja for linking. Add -Werror to turn compiler warnings into errors
+# with LTO. (meson's werror should arguably do this, but meanwhile we need to)
+exec g++ "$@" -Werror

.gitlab-ci/build/gcc-link-werror.sh

@@ -0,0 +1,15 @@
+#!/bin/sh -e
+
+if [ "$(ps -p $(ps -p $PPID -o ppid --no-headers) -o comm --no-headers)" != ninja ]; then
+    # Not invoked by ninja (e.g. for a meson feature check)
+    exec gcc "$@"
+fi
+
+if [ "$(eval printf "'%s'" "\"\${$(($#-1))}\"")" = "-c" ]; then
+    # Not invoked for linking
+    exec gcc "$@"
+fi
+
+# Compiler invoked by ninja for linking. Add -Werror to turn compiler warnings into errors
+# with LTO. (meson's werror should arguably do this, but meanwhile we need to)
+exec gcc "$@" -Werror

.gitlab-ci/build/gitlab-ci.yml

@@ -25,11 +25,13 @@
     - |
       export PATH="/usr/lib/ccache:$PATH"
       export CCACHE_BASEDIR="$PWD"
+      if test -x /usr/bin/ccache; then
         section_start ccache_before "ccache stats before build"
         ccache --show-stats
         section_end ccache_before
+      fi
   after_script:
-    - ccache --show-stats | grep "cache hit rate"
+    - if test -x /usr/bin/ccache; then ccache --show-stats | grep "cache hit rate"; fi
     - !reference [default, after_script]
 
 .build-windows:
@@ -182,7 +184,7 @@ debian-build-testing:
     GALLIUM_DRIVERS: "iris,nouveau,kmsro,r300,r600,freedreno,swrast,svga,v3d,vc4,virgl,etnaviv,panfrost,lima,zink,d3d12,asahi,crocus"
     VULKAN_DRIVERS: swrast
     EXTRA_OPTION: >
-      --native-file .gitlab-ci/build/meson-native-lto-wrappers.txt
+      --native-file .gitlab-ci/build/meson-native-lto-wrappers-ccache.txt
       -D spirv-to-dxil=true
       -D osmesa=true
       -D tools=drm-shim,etnaviv,freedreno,glsl,intel,intel-ui,nir,nouveau,lima,panfrost,asahi

.gitlab-ci/build/meson-native-lto-wrappers-ccache.txt

@@ -0,0 +1,3 @@
+[binaries]
+c = 'ccache-gcc-link-werror.sh'
+cpp = 'ccache-g++-link-werror.sh'

.gitlab-ci/build/meson-native-lto-wrappers.txt

@@ -1,3 +1,3 @@
 [binaries]
-c = 'ccache-gcc-link-werror.sh'
-cpp = 'ccache-g++-link-werror.sh'
+c = 'gcc-link-werror.sh'
+cpp = 'g++-link-werror.sh'

.gitlab-ci/container/container_post_build.sh

@@ -7,4 +7,6 @@ fi
 # Clean up any build cache for rust.
 rm -rf /.cargo
 
+if test -x /usr/bin/ccache; then
     ccache --show-stats
+fi

.gitlab-ci/container/container_pre_build.sh

@@ -1,5 +1,6 @@
 #!/bin/sh
 
+if test -x /usr/bin/ccache; then
     if test -f /etc/debian_version; then
         CCACHE_PATH=/usr/lib/ccache
     elif test -f /etc/alpine-release; then
@@ -19,6 +20,9 @@ export PATH=$CCACHE_PATH:$PATH
     export CC="${CCACHE_PATH}/gcc"
     export CXX="${CCACHE_PATH}/g++"
 
+    ccache --show-stats
+fi
+
 # When not using the mold linker (e.g. unsupported architecture), force
 # linkers to gold, since it's so much faster for building.  We can't use
 # lld because we're on old debian and it's buggy.  ming fails meson builds
@@ -27,8 +31,6 @@ find /usr/bin -name \*-ld -o -name ld | \
     grep -v mingw | \
     xargs -n 1 -I '{}' ln -sf '{}.gold' '{}'
 
-ccache --show-stats
-
 # Make a wrapper script for ninja to always include the -j flags
 {
     echo '#!/bin/sh -x'