From b66680ad32e280b3c4286a9abfef8df5ff566ed0 Mon Sep 17 00:00:00 2001
From: Mattias Engdegård
Date: Fri, 17 Oct 2025 13:03:13 +0200
Subject: Disable -Wclobbered around exec_byte_code (bug#79610)

* src/bytecode.c (exec_byte_code):
The old hack for working around spurious -Wclobbered warnings from GCC
no longer suffices; disable the warning locally.
This also makes the code slightly smaller and faster.
---
 src/bytecode.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/src/bytecode.c b/src/bytecode.c
index ad3844d0213..64d9e5d27c6 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -463,6 +463,14 @@ valid_sp (struct bc_thread_state *bc, Lisp_Object *sp)
 #define BC_REG_PC
 #endif
 
+/* It seems difficult to avoid spurious -Wclobbered diagnostics from GCC
+   in exec_byte_code, so turn the warning off around that function.
+   See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21161>.  */
+#if __GNUC__ && !__clang__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wclobbered"
+#endif
+
 /* Execute the byte-code in FUN.  ARGS_TEMPLATE is the function arity
    encoded as an integer (the one in FUN is ignored), and ARGS, of
    size NARGS, should be a vector of the actual arguments.  The
@@ -540,11 +548,6 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
     for (ptrdiff_t i = nargs - rest; i < nonrest; i++)
       PUSH (Qnil);
 
-#if GCC_LINT && __GNUC__ && !__clang__
-  Lisp_Object *volatile saved_vectorp;
-  unsigned char const *volatile saved_bytestr_data;
-#endif
-
   while (true)
     {
       ptrdiff_t op;
@@ -987,12 +990,6 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
 		Lisp_Object fun = fp->fun;
 		Lisp_Object bytestr = AREF (fun, CLOSURE_CODE);
 		Lisp_Object vector = AREF (fun, CLOSURE_CONSTANTS);
-#if GCC_LINT && __GNUC__ && !__clang__
-		/* These useless assignments pacify GCC 14.2.1 x86-64
-		   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21161>.  */
-		bytestr_data = saved_bytestr_data;
-		vectorp = saved_vectorp;
-#endif
 		bytestr_data = SDATA (bytestr);
 		vectorp = XVECTOR (vector)->contents;
 		if (BYTE_CODE_SAFE)
@@ -1006,10 +1003,6 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
 		goto op_branch;
 	      }
 
-#if GCC_LINT && __GNUC__ && !__clang__
-	    saved_vectorp = vectorp;
-	    saved_bytestr_data = bytestr_data;
-#endif
 	    NEXT;
 	  }
 
@@ -1807,6 +1800,11 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
   return result;
 }
 
+#if __GNUC__ && !__clang__
+#pragma GCC diagnostic pop
+#endif
+
+
 /* `args_template' has the same meaning as in exec_byte_code() above.  */
 Lisp_Object
 get_byte_code_arity (Lisp_Object args_template)
-- 
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