fix: tools: win32spawn: use GCC @response file for long link commands

tools/win32spawn.py

@@ -24,6 +24,7 @@
 
 import os
 import subprocess
+import tempfile
 
 class Win32Spawn:
     def spawn(self, sh, escape, cmd, args, env):
@@ -51,7 +52,38 @@ def spawn(self, sh, escape, cmd, args, env):
         os.environ['PATH'] = _e['PATH']
 
         try:
-            proc = subprocess.Popen(cmdline, env=_e, shell=False)
+            # On Windows, CreateProcess has a ~32K command line limit.
+            # When the link command gets very long (many object files),
+            # use a GCC @response file to shorten the command line.
+            if len(cmdline) > 25000 and (cmd.find('gcc') != -1 or cmd.find('g++') != -1):
+                # Split args: object files go into response file;
+                # flags stay on command line. Libraries (-l*, -L*) must
+                # come after object files for proper symbol resolution.
+                pre_obj_flags = []
+                post_obj_flags = []
+                obj_args = []
+                seen_obj = False
+                for arg in args[1:]:
+                    stripped = arg.strip('"')
+                    if stripped.endswith('.o') or stripped.endswith('.a'):
+                        obj_args.append(stripped)
+                        seen_obj = True
+                    elif not seen_obj:
+                        pre_obj_flags.append(stripped)
+                    else:
+                        post_obj_flags.append(stripped)
+
+                # Create response file for object files
+                fd, rsp_path = tempfile.mkstemp(suffix='.rsp', prefix='scons_link_')
+                with os.fdopen(fd, 'w') as f:
+                    for obj in obj_args:
+                        # GCC @file treats backslash as escape char;
+                        # use forward slashes for Windows paths
+                        f.write(obj.replace('\\', '/') + '\n')
+                rsp_args = [cmd] + pre_obj_flags + ['@' + rsp_path] + post_obj_flags
+                proc = subprocess.Popen(rsp_args, env=_e, shell=False)
+            else:
+                proc = subprocess.Popen(cmdline, env=_e, shell=False)
         except Exception as e:
             print('Error in calling command:' + cmdline.split(' ')[0])
             print('Exception: ' + os.strerror(e.errno))
@@ -62,4 +94,13 @@ def spawn(self, sh, escape, cmd, args, env):
         finally:
             os.environ['PATH'] = old_path
 
-        return proc.wait()
+        ret = proc.wait()
+
+        # Clean up response file if used
+        if len(cmdline) > 25000 and (cmd.find('gcc') != -1 or cmd.find('g++') != -1):
+            try:
+                os.unlink(rsp_path)
+            except:
+                pass
+
+        return ret