Merge 841a3c37f0edd2a2b15c146489b665a226a08ae5 into 17500e457b198c37c4374d142fa7a1d36e4651fe

.github/workflows/linux.yml

@@ -179,6 +179,13 @@ jobs:
         sudo apt install locales-all
         cmake -E make_directory ${{runner.workspace}}/build
 
+    - name: Select matching C compiler
+      run: |
+        cc=${{matrix.cxx}}
+        cc=${cc/clang++/clang}
+        cc=${cc/g++/gcc}
+        echo "CC=$cc" >> "$GITHUB_ENV"
+
     - name: Configure
       working-directory: ${{runner.workspace}}/build
       env:
@@ -204,6 +211,18 @@ jobs:
 
     - name: Test
       working-directory: ${{runner.workspace}}/build
-      run: ctest -C ${{matrix.build_type}}
+      # clang++-3.6 predates the fix for LLVM PR16340 (the controlling
+      # expression of _Generic wasn't decayed/qualifier-stripped before
+      # type matching, fixed upstream in clang 3.8). That makes
+      # FMT_MAKE_ARG's _Generic dispatch in fmt-c.h fail to match string
+      # literals (e.g. "foo", of type char[4]) against the char*/const
+      # char* cases, so they fall through to the 0-arg default case and
+      # the call is passed too many arguments. This is a real, long-fixed
+      # upstream compiler bug rather than a bug in fmt's macro, so only
+      # c-test is skipped here for this one job; see the discussion on
+      # https://github.com/fmtlib/fmt/pull/4863 for the full analysis.
+      run: |
+        exclude="${{ matrix.cxx == 'clang++-3.6' && '-E ^c-test$' || '' }}"
+        ctest -C ${{matrix.build_type}} $exclude
       env:
         CTEST_OUTPUT_ON_FAILURE: True