do not use gcc15

Author: perazz

index.js

@@ -208,13 +208,22 @@ async function installFromSource(fpmVersion, fpmRepo){
   try {
 
     // Find gfortran - it may be versioned (e.g., gfortran-13)
+    // Use gcc <= 13 for compatibility with older fpm versions
     let gfortranCmd = 'gfortran';
+    let foundGfortran = false;
+
     try {
       await exec.exec('which', ['gfortran'], { silent: true });
+      foundGfortran = true;
     } catch (error) {
-      // Try to find a versioned gfortran
+      // gfortran not found, try versioned
+    }
+
+    // If we found unversioned gfortran, check if it's gcc >= 14
+    // If so, or if we didn't find unversioned gfortran, look for a versioned one <= 13
+    if (!foundGfortran || true) {  // Always prefer versioned <= 13 for compatibility
       let foundVersioned = false;
-      for (const ver of [15, 14, 13, 12, 11, 10]) {
+      for (const ver of [13, 12, 11, 10]) {
         try {
           await exec.exec('which', [`gfortran-${ver}`], { silent: true });
           gfortranCmd = `gfortran-${ver}`;
@@ -226,12 +235,12 @@ async function installFromSource(fpmVersion, fpmRepo){
         }
       }
 
-      if (!foundVersioned) {
+      if (!foundVersioned && !foundGfortran) {
         core.setFailed(
           'gfortran is required to build fpm from source on macOS ARM64.\n' +
-          'Please install it before running this action, for example:\n' +
+          'Please install gcc version 10-13 before running this action, for example:\n' +
           '  - name: Install gfortran\n' +
-          '    run: brew install gcc\n' +
+          '    run: brew install gcc@13\n' +
           'Or use fortran-lang/setup-fortran to install a Fortran compiler.'
         );
         return;