ci: Convert CompilerWarnings job to meson

This is part of the overall move toward meson.  This particular step
was previously held up because the headerscheck target was not ported
to meson, but this has been done a few months ago (commit
e82fc27e09).  This conversion is relatively straightforward.  The
scope of each individual build step (e.g., what features it enables,
what optimization level it uses) has been maintained, except as noted.

It actually covers a bit more now, as it also compiles various test
code via the testprep target.

One thing we're losing is the sharing of the configure cache between
the steps (gcc.cache, clang.cache).  There is a way to do that in
meson (meson-private/coredata.dat), but it's not meant to be used
across different build directories, and so making that work might be a
more significant restructuring.  The overall performance of the CI
runs seems to be about on par nonetheless.

Bitcode for JIT inlining is no longer built in this job, since meson
doesn't support it.  It added little to warning coverage, and the
Linux autoconf job still builds it.

Co-authored-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/e52e2c29-4834-4c64-a200-eddcba38fb4d%40eisentraut.org

.github/workflows/pg-ci.yml

@@ -94,7 +94,7 @@ env:
     -Dzlib=enabled
     -Dzstd=enabled
 
-  # Shared between the Linux autoconf job and the CompilerWarnings jobs
+  # Used by the Linux autoconf job
   LINUX_CONFIGURE_FEATURES: >-
     --with-gssapi
     --with-icu
@@ -1151,10 +1151,6 @@ jobs:
   # with various combinations of cassert/dtrace flags. Trace probes have
   # a history of getting accidentally broken; the matrix is there to
   # catch that.
-  #
-  # The autoconf cache files (gcc.cache / clang.cache) are intentionally
-  # reused across the matrix entries that share a compiler, so we don't
-  # pay for full feature detection on every entry.
   compiler-warnings:
     name: CompilerWarnings
     needs: [setup, sanity-check]
@@ -1170,7 +1166,17 @@ jobs:
       # Use larger ccache cache as this job compiles with multiple
       # compilers / flag combinations.
       CCACHE_MAXSIZE: "1G"
-      DEFAULT_BUILD: world-bin
+
+      # Enable everything else in LINUX_CONFIGURE_FEATURES but not in
+      # MESON_COMMON_FEATURES.
+      MESON_FEATURES: >-
+        -Dgssapi=enabled
+        -Dlibcurl=enabled
+        -Dllvm=enabled
+        -Dpam=enabled
+        -Dselinux=enabled
+        -Dsystemd=enabled
+        -Duuid=ossp
 
     steps:
       - *nix_sysinfo_step
@@ -1178,33 +1184,30 @@ jobs:
       - *ccache_restore_default_step
       - *ccache_restore_branch_step
 
-      - name: Setup workspace
-        run: |
-          echo "COPT=-Werror" > src/Makefile.custom
-
       # gcc, cassert off, dtrace on
       - name: gcc warnings + (dtrace)
         if: ${{ !cancelled() }}
         env:
-          CONF: ${{env.LINUX_CONFIGURE_FEATURES}} --cache gcc.cache --enable-dtrace
+          CONF: ${{env.MESON_COMMON_FEATURES}} ${{env.MESON_FEATURES}} -Ddtrace=enabled
           CC: ccache gcc
           CXX: ccache g++
-          CLANG: ccache clang
         run: &compiler_warnings_cmd |
           echo "::group::configure"
-          ./configure \
+          rm -rf build
+          meson setup \
+            -Dwerror=true \
+            -Ddebug=false \
             ${{env.CONF}} \
-            CLANG="ccache clang"
+            build
           echo "::endgroup::"
 
-          make -s -j${{env.BUILD_JOBS}} clean
-          make -s -j${{env.BUILD_JOBS}} ${{env.DEFAULT_BUILD}}
+          ninja -C build --quiet -j${{env.BUILD_JOBS}} ${{env.MBUILD_TARGET}}
 
       # gcc, cassert on, dtrace off
       - name: gcc warnings + (cassert)
         if: ${{ !cancelled() }}
         env:
-          CONF: ${{env.LINUX_CONFIGURE_FEATURES}} --cache gcc.cache --enable-cassert
+          CONF: ${{env.MESON_COMMON_FEATURES}} ${{env.MESON_FEATURES}} -Dcassert=true
           CC: ccache gcc
           CXX: ccache g++
         run: *compiler_warnings_cmd
@@ -1213,7 +1216,7 @@ jobs:
       - name: clang warnings
         if: ${{ !cancelled() }}
         env:
-          CONF: ${{env.LINUX_CONFIGURE_FEATURES}} --cache clang.cache
+          CONF: ${{env.MESON_COMMON_FEATURES}} ${{env.MESON_FEATURES}}
           CC: ccache clang
           CXX: ccache clang++
         run: *compiler_warnings_cmd
@@ -1222,7 +1225,7 @@ jobs:
       - name: clang warnings + (cassert + dtrace)
         if: ${{ !cancelled() }}
         env:
-          CONF: ${{env.LINUX_CONFIGURE_FEATURES}} --cache clang.cache --enable-cassert --enable-dtrace
+          CONF: ${{env.MESON_COMMON_FEATURES}} ${{env.MESON_FEATURES}} -Dcassert=true -Ddtrace=enabled
           CC: ccache clang
           CXX: ccache clang++
         run: *compiler_warnings_cmd
@@ -1230,9 +1233,12 @@ jobs:
       - name: mingw warnings (cross compilation)
         if: ${{ !cancelled() }}
         env:
-          CONF: --host=x86_64-w64-mingw32ucrt --enable-cassert --without-icu
-          CC: ccache x86_64-w64-mingw32ucrt-gcc
-          CXX: ccache x86_64-w64-mingw32ucrt-g++
+          CONF: >-
+            --cross-file src/tools/ci/mingw-cross-file.txt
+            -Dcassert=true
+            -Dauto_features=disabled
+            -Dzlib=enabled
+          MBUILD_TARGET: all
         run: *compiler_warnings_cmd
 
       ###
@@ -1242,34 +1248,38 @@ jobs:
       - name: Build documentation
         if: ${{ !cancelled() }}
         env:
-          CONF: --cache gcc.cache
+          CONF: -Dauto_features=disabled -Ddocs=enabled
           CC: ccache gcc
           CXX: ccache g++
-          DEFAULT_BUILD: -C doc
+          MBUILD_TARGET: docs
         run: *compiler_warnings_cmd
 
       ###
       # Verify headerscheck / cpluspluscheck succeed
       #
-      # - Run both in same script to increase parallelism, use -k to get
-      #   result of both
+      # - Run both in the same ninja invocation to increase parallelism, use
+      #   -k 0 to get the result of both
       # - Use -fmax-errors, as particularly cpluspluscheck can be very verbose
       ###
       - name: headerscheck + cpluspluscheck
         if: ${{ !cancelled() }}
+        env:
+          CONF: ${{env.MESON_COMMON_FEATURES}} ${{env.MESON_FEATURES}}
+          CC: ccache gcc
+          CXX: ccache g++
+          EXTRAFLAGS: -fmax-errors=10
         run: |
           echo "::group::configure"
-          ./configure \
-            ${{env.LINUX_CONFIGURE_FEATURES}} \
-            --cache gcc.cache \
-            --quiet \
-            CC="ccache gcc" CXX="ccache g++" CLANG="ccache clang"
+          rm -rf build
+          meson setup \
+            -Dwerror=true \
+            -Ddebug=false \
+            ${{env.CONF}} \
+            build
           echo "::endgroup::"
 
-          make -s -j${{env.BUILD_JOBS}} clean
-          make -s -j${{env.BUILD_JOBS}} -k ${{env.CHECKFLAGS}} \
-            headerscheck cpluspluscheck \
-            EXTRAFLAGS='-fmax-errors=10'
+          ninja -C build --quiet -j${{env.BUILD_JOBS}} -k 0 \
+            headerscheck cpluspluscheck
 
       - *ccache_decide_save_step
       - *ccache_save_step

src/tools/ci/mingw-cross-file.txt

@@ -0,0 +1,22 @@
+# Meson cross file for cross compiling to Windows with the Debian
+# mingw-w64 toolchain, as used by the CompilerWarnings CI job.
+#
+# ccache is spelled out here because meson's automatic ccache
+# detection does not apply to compilers that are named in a cross
+# file.
+
+[constants]
+prefix = 'x86_64-w64-mingw32ucrt-'
+
+[binaries]
+c = ['ccache', prefix + 'gcc']
+cpp = ['ccache', prefix + 'g++']
+ar = prefix + 'ar'
+strip = prefix + 'strip'
+windres = prefix + 'windres'
+
+[host_machine]
+system = 'windows'
+cpu_family = 'x86_64'
+cpu = 'x86_64'
+endian = 'little'