From c5aaff567dc4d70c4105ce3fde9bebbbf90c894f Mon Sep 17 00:00:00 2001
From: flink <w741069229@gmail.com>
Date: Mon, 20 Jul 2026 21:16:49 -0400
Subject: [PATCH] Set matching CC alongside CXX in Linux CI matrix

The Configure step only set CXX, so CMake's C compiler detection
fell back to whatever the default happened to be on the runner,
independent of which C++ compiler the matrix entry was actually
testing (e.g. CXX=clang++-3.6 but CC left to detect GCC 11).

Derive CC from the same matrix.cxx value the job already installs
a matching compiler for.
---
 .github/workflows/linux.yml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index e9a21424..8d45e478 100644
--- a/.github/workflows/linux.yml
+++ b/.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: