working mesa-git

overlays/mesa-gcc/default.nix

@@ -1,7 +1,40 @@
 { ... }:
 
 final: prev: {
-  mesa = prev.mesa.override {
+  mesa = (prev.mesa.overrideAttrs (old: rec {
+    version = "git-unstable-2026-02-12";
+    src = prev.fetchFromGitLab {
+      domain = "gitlab.freedesktop.org";
+      owner = "mesa";
+      repo = "mesa";
+      rev = "main";
+      hash = "sha256-5gpLORvbV3skALrQa0VxTJJarYjuq+KyTxDm9HtZNbQ=";
+    };
+    patches = [];
+    buildInputs = old.buildInputs ++ (with prev.llvmPackages_21; [ 
+      clang-unwrapped
+      libclang
+    ]);
+    
+    # Create symlinks to clang libraries so meson can find them
+    preConfigure = (old.preConfigure or "") + ''
+      mkdir -p $NIX_BUILD_TOP/clang-libs
+      for lib in ${prev.llvmPackages_21.clang-unwrapped.lib}/lib/*.a; do
+        ln -sf "$lib" "$NIX_BUILD_TOP/clang-libs/"
+      done
+      export LIBRARY_PATH="$NIX_BUILD_TOP/clang-libs:''${LIBRARY_PATH:-}"
+      export CXXFLAGS="$CXXFLAGS -fno-strict-aliasing"
+    '';
+    
+    mesonFlags = 
+      (builtins.filter (flag: 
+        !(prev.lib.hasPrefix "-Dclang-libdir=" flag) &&
+        flag != "--sysconfdir=/etc"
+      ) old.mesonFlags) ++ [
+      "-Dsysconfdir=${placeholder "out"}/etc"
+    ] ++ (if prev.stdenv.hostPlatform.is64bit then [ "-Dintel-rt=enabled" ] else [ "-Dintel-rt=disabled" ]);
+  })).override {
     stdenv = prev.gcc14Stdenv;
   };
 }
+