From: Martin Uecker <uecker@tugraz.at>
Date: Sun, 26 Apr 2026 16:28:16 +0000 (+0200)
Subject: c: argument expressions may be evaluated too often by typeof [PR124576]
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9aaedeaced055efe5041004e0643f4f3127c6ce9;p=thirdparty%2Fgcc.git

c: argument expressions may be evaluated too often by typeof [PR124576]

When there are multiple declarators in a declaration and the type
is specified via typeof, an expression inside the argument of
typeof may be evaluated multiple times.  Fix this by adding a
save expression.

	PR c/124576

gcc/c/ChangeLog:
	* c-decl.cc (declspecs_add_type): Add save_expr.

gcc/testsuite/ChangeLog:
	* gcc.dg/pr124576.c: New test.
---

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 5e5193ed880..cc07e05e336 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -13136,11 +13136,12 @@ declspecs_add_type (location_t loc, struct c_declspecs *specs,
 	    }
 	  if (spec.expr)
 	    {
+	      tree expr = save_expr (fold_convert (void_type_node, spec.expr));
 	      if (specs->expr)
-		specs->expr = build2 (COMPOUND_EXPR, TREE_TYPE (spec.expr),
-				      specs->expr, spec.expr);
+		specs->expr = build2 (COMPOUND_EXPR, TREE_TYPE (expr),
+				      specs->expr, expr);
 	      else
-		specs->expr = spec.expr;
+		specs->expr = expr;
 	      specs->expr_const_operands &= spec.expr_const_operands;
 	    }
 	}
diff --git a/gcc/testsuite/gcc.dg/pr124576.c b/gcc/testsuite/gcc.dg/pr124576.c
new file mode 100644
index 00000000000..b66969d60fa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr124576.c
@@ -0,0 +1,12 @@
+/* { dg-do run } */
+/* { dg-options "-std=c99" } */
+
+int main()
+{
+    int i = 0;
+    int j = 0;
+    __typeof__((__typeof__(int[i++])*)(j++, (void*)0)) a, b, c;
+    if (1 != j)
+	    __builtin_abort();
+}
+