Problem: gcc-ar fails when a @file is passed to it:

$ cat rsp
--version
$ gcc-ar @rsp
/usr/bin/ar: invalid option -- '@'

This is because a dash '-' is prepended to the first
argument if it doesn't start with one, resulting in
the wrong call 'ar -@rsp'.

Fix: Expand argv to get rid of any @files and if any
expansions were made, pass everything through a
temporary response file.

$ gcc-ar @rsp
GNU ar (GNU Binutils for Debian) 2.35.2
...


PR gcc-ar/77576
* gcc/gcc-ar.cc (main): Expand argv and use
temporary response file to call ar if any
expansions were made.
---
 gcc/gcc-ar.cc | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/gcc/gcc-ar.cc b/gcc/gcc-ar.cc
index 4e4c525927d..417c4913793 100644
--- a/gcc/gcc-ar.cc
+++ b/gcc/gcc-ar.cc
@@ -135,6 +135,10 @@ main (int ac, char **av)
   int k, status, err;
   const char *err_msg;
   const char **nargv;
+  char **old_argv;
+  const char *rsp_file = NULL;
+  const char *rsp_arg = NULL;
+  const char *rsp_argv[3];
   bool is_ar = !strcmp (PERSONALITY, "ar");
   int exit_code = FATAL_EXIT_CODE;
   int i;
@@ -209,6 +213,13 @@ main (int ac, char **av)
  }
     }

+  /* Expand any @files before modifying the command line
+     and use a temporary response file if there were any.  */
+  old_argv = av;
+  expandargv (&ac, &av);
+  if (av != old_argv)
+    rsp_file = make_temp_file ("");
+
   /* Prepend - if necessary.  */
   if (is_ar && av[1] && av[1][0] != '-')
     av[1] = concat ("-", av[1], NULL);
@@ -225,6 +236,39 @@ main (int ac, char **av)
     nargv[j + k] = av[k];
   nargv[j + k] = NULL;

+  /* If @file was passed, put nargv into the temporary response
+     file and then change it to a single @FILE argument, where
+     FILE is the temporary filename.  */
+  if (rsp_file)
+    {
+      FILE *f;
+      int status;
+      f = fopen (rsp_file, "w");
+      if (f == NULL)
+        {
+          fprintf (stderr, "Cannot open temporary file %s\n", rsp_file);
+          exit (1);
+        }
+      status = writeargv (
+          CONST_CAST2 (char * const *, const char **, nargv) + 1, f);
+      if (status)
+        {
+          fprintf (stderr, "Cannot write to temporary file %s\n",
rsp_file);
+          exit (1);
+        }
+      status = fclose (f);
+      if (EOF == status)
+        {
+          fprintf (stderr, "Cannot close temporary file %s\n", rsp_file);
+          exit (1);
+        }
+      rsp_arg = concat ("@", rsp_file, NULL);
+      rsp_argv[0] = nargv[0];
+      rsp_argv[1] = rsp_arg;
+      rsp_argv[2] = NULL;
+      nargv = rsp_argv;
+    }
+
   /* Run utility */
   /* ??? the const is misplaced in pex_one's argv? */
   err_msg = pex_one (PEX_LAST|PEX_SEARCH,
@@ -249,5 +293,8 @@ main (int ac, char **av)
   else
     exit_code = SUCCESS_EXIT_CODE;

+  if (rsp_file)
+    unlink (rsp_file);
+
   return exit_code;
 }
-- 
2.30.2