[gcc r16-9308] Make -Wuse-after-free alias for -Wuse-after-free=1 [PR124058]

https://gcc.gnu.org/g:872f2200a1b78e8ecb6a2596444c48470dc904f3

commit r16-9308-g872f2200a1b78e8ecb6a2596444c48470dc904f3
Author: Torbjörn SVENSSON <[email protected]>
Date:   Sun Jul 12 20:42:55 2026 +0200

    Make -Wuse-after-free alias for -Wuse-after-free=1 [PR124058]
    
    GCC currently treats -Wuse-after-free and -Wuse-after-free= as separate
    options internally, with OPT_Wuse_after_free for no argument and
    OPT_Wuse_after_free_ with argument.  Make -Wuse-after-free an alias for
    -Wuse-after-free=1 so both forms go through the same option code.
    
    Switch the warning and suppression sites to OPT_Wuse_after_free_ so
    pragmas, diagnostic classification, and suppression all refer to the same
    option.
    
    Document that -Wuse-after-free is equivalent to -Wuse-after-free=1.
    
    On Arm AAPCS targets, constructors and destructors return this.  In
    maybe_prepare_return_this, suppressing OPT_Wuse_after_free for this records
    the suppression under NW_OTHER, since OPT_Wuse_after_free is not explicitly
    mapped to a diagnostic group.  That can suppress unrelated NW_OTHER
    warnings, such as -Wdeprecated-declarations.  OPT_Wuse_after_free_ is
    mapped to NW_DANGLING, so using it keeps the suppression scoped to the
    use-after-free warning.
    
            PR driver/124058
    
    gcc/ChangeLog:
    
            * common.opt (Wuse-after-free): Make an alias for
            -Wuse-after-free=1.
            * doc/invoke.texi: Document alias.
            * gimple-ssa-warn-access.cc (pass_waccess::warn_invalid_pointer):
            Use OPT_Wuse_after_free_.
            * gcc-diagnostic-spec.cc (nowarn_spec_t::nowarn_spec_t):
            Likewise.
    
    gcc/cp/ChangeLog:
    
            * decl.cc (maybe_prepare_return_this): Use OPT_Wuse_after_free_.
    
    gcc/testsuite/ChangeLog:
    
            * c-c++-common/Wuse-after-free-8.c: New test.
    
    Signed-off-by: Torbjörn SVENSSON <[email protected]>
    (cherry picked from commit c5627f93a8259131da2cdebee6d9b0e1f2de1a60)

Diff:
---
 gcc/common.opt                                 |  3 +--
 gcc/cp/decl.cc                                 |  2 +-
 gcc/doc/invoke.texi                            |  1 +
 gcc/gcc-diagnostic-spec.cc                     |  1 -
 gcc/gimple-ssa-warn-access.cc                  | 10 +++++-----
 gcc/testsuite/c-c++-common/Wuse-after-free-8.c | 26 ++++++++++++++++++++++++++
 6 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/gcc/common.opt b/gcc/common.opt
index 5d0e255a40d9..204c8ae721bd 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -561,8 +561,7 @@ Common Var(warn_auto_profile) Warning
 Warn about problems with auto-profile data.
 
 Wuse-after-free
-Common Var(warn_use_after_free) Warning
-Warn for uses of pointers to deallocated storage.
+Common Alias(Wuse-after-free=, 1, 0) Warning
 
 Wuse-after-free=
 Common Joined RejectNegative UInteger Var(warn_use_after_free) Warning IntegerRange(0, 3)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 9b10899f5c20..095cef2f2e50 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -20292,7 +20292,7 @@ maybe_prepare_return_this (tree cdtor)
   if (targetm.cxx.cdtor_returns_this ())
     if (tree val = DECL_ARGUMENTS (cdtor))
       {
-	suppress_warning (val, OPT_Wuse_after_free);
+	suppress_warning (val, OPT_Wuse_after_free_);
 	return val;
       }
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index aa80ebd0ced1..1d69e434e824 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8442,6 +8442,7 @@ Warn about uses of pointers to dynamically allocated objects that have
 been rendered indeterminate by a call to a deallocation function.
 The warning is enabled at all optimization levels but may yield different
 results with optimization than without.
+@option{-Wuse-after-free} is equivalent to @option{-Wuse-after-free=1}.
 
 @table @gcctabopt
 @item -Wuse-after-free=1
diff --git a/gcc/gcc-diagnostic-spec.cc b/gcc/gcc-diagnostic-spec.cc
index 813625e28773..dd631699539d 100644
--- a/gcc/gcc-diagnostic-spec.cc
+++ b/gcc/gcc-diagnostic-spec.cc
@@ -100,7 +100,6 @@ nowarn_spec_t::nowarn_spec_t (opt_code opt)
 
     case OPT_Wdangling_pointer_:
     case OPT_Wreturn_local_addr:
-    case OPT_Wuse_after_free:
     case OPT_Wuse_after_free_:
       m_bits = NW_DANGLING;
       break;
diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc
index 98de5df86b02..f1fb92f6be1c 100644
--- a/gcc/gimple-ssa-warn-access.cc
+++ b/gcc/gimple-ssa-warn-access.cc
@@ -3992,7 +3992,7 @@ pass_waccess::warn_invalid_pointer (tree ref, gimple *use_stmt,
       if (!var)
 	ref = NULL_TREE;
       /* Don't warn for cases like when a cdtor returns 'this' on ARM.  */
-      else if (warning_suppressed_p (var, OPT_Wuse_after_free))
+      else if (warning_suppressed_p (var, OPT_Wuse_after_free_))
 	return;
       else if (DECL_ARTIFICIAL (var))
 	ref = NULL_TREE;
@@ -4014,18 +4014,18 @@ pass_waccess::warn_invalid_pointer (tree ref, gimple *use_stmt,
       if (!m_early_checks_p
 	  || (equality && warn_use_after_free < 3)
 	  || (maybe && warn_use_after_free < 2)
-	  || warning_suppressed_p (use_stmt, OPT_Wuse_after_free))
+	  || warning_suppressed_p (use_stmt, OPT_Wuse_after_free_))
 	return;
 
       const tree inval_decl = gimple_call_fndecl (inval_stmt);
 
       auto_diagnostic_group d;
-      if ((ref && warning_at (use_loc, OPT_Wuse_after_free,
+      if ((ref && warning_at (use_loc, OPT_Wuse_after_free_,
 			      (maybe
 			       ? G_("pointer %qE may be used after %qD")
 			       : G_("pointer %qE used after %qD")),
 			      ref, inval_decl))
-	  || (!ref && warning_at (use_loc, OPT_Wuse_after_free,
+	  || (!ref && warning_at (use_loc, OPT_Wuse_after_free_,
 			      (maybe
 			       ? G_("pointer may be used after %qD")
 			       : G_("pointer used after %qD")),
@@ -4033,7 +4033,7 @@ pass_waccess::warn_invalid_pointer (tree ref, gimple *use_stmt,
 	{
 	  location_t loc = gimple_location (inval_stmt);
 	  inform (loc, "call to %qD here", inval_decl);
-	  suppress_warning (use_stmt, OPT_Wuse_after_free);
+	  suppress_warning (use_stmt, OPT_Wuse_after_free_);
 	}
       return;
     }
diff --git a/gcc/testsuite/c-c++-common/Wuse-after-free-8.c b/gcc/testsuite/c-c++-common/Wuse-after-free-8.c
new file mode 100644
index 000000000000..07e7348e801f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wuse-after-free-8.c
@@ -0,0 +1,26 @@
+/* Verify -Wuse-after-free is an alias for -Wuse-after-free=1. */
+/* { dg-do compile } */
+/* { dg-options "-O0 -Wuse-after-free" } */
+
+#if __cplusplus
+#  define EXTERN_C extern "C"
+#else
+#  define EXTERN_C extern
+#endif
+
+EXTERN_C void free (void *);
+
+void sink (void *);
+
+void warn_call_after_free (void *p)
+{
+  free (p);
+  sink (p);         // { dg-warning "pointer 'p' used" }
+}
+
+void warn_cond_call_after_free (void *p, int c)
+{
+  free (p);
+  if (c)
+    sink (p);
+}