builtins: Fix up strspn/strcspn folding [PR119219]

The PR119204 r15-7955 fix caused some regressions.
The problem is that the fold_builtin* APIs document that expr is
either a CALL_EXPR of the call or NULL, so using TREE_TYPE (expr)
can crash e.g. during constexpr evaluation etc.

As can be seen in the surrounding patch, for the neighbouring builtins
(both modf and strpbrk) fold_builtin_2 passes down type, which is the
result type, TREE_TYPE (TREE_TYPE (fndecl)) and those builtins use it
to build the return value, while strspn was always building size_type_node
and strcspn had this change from that to TREE_TYPE (expr).
The patch passes type to these two and uses it there as well.

The patch keeps passing expr because it is used in the
check_nul_terminated_array calls done for both strspn and strcspn,
those calls clearly can deal with NULL expr but prefer if it is non-NULL
for some warning.

2025-03-12  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/119204
	PR middle-end/119219
	* builtins.cc (fold_builtin_2): Pass type as another argument
	to fold_builtin_strspn and fold_builtin_strcspn.
	(fold_builtin_strspn): Add type argument, use it instead of
	size_type_node.
	(fold_builtin_strcspn): Add type argument, use it instead of
	TREE_TYPE (expr).

1 files changed, 9 insertions, 11 deletions

diff --git a/gcc/builtins.cc b/gcc/builtins.cc
index 02556e6..956d3cc 100644
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -176,8 +176,8 @@ static tree fold_builtin_iseqsig (location_t, tree, tree);
 static tree fold_builtin_varargs (location_t, tree, tree*, int);
 
 static tree fold_builtin_strpbrk (location_t, tree, tree, tree, tree);
-static tree fold_builtin_strspn (location_t, tree, tree, tree);
-static tree fold_builtin_strcspn (location_t, tree, tree, tree);
+static tree fold_builtin_strspn (location_t, tree, tree, tree, tree);
+static tree fold_builtin_strcspn (location_t, tree, tree, tree, tree);
 
 static rtx expand_builtin_object_size (tree);
 static rtx expand_builtin_memory_chk (tree, rtx, machine_mode,
@@ -10800,10 +10800,10 @@ fold_builtin_2 (location_t loc, tree expr, tree fndecl, tree arg0, tree arg1)
       return fold_builtin_modf (loc, arg0, arg1, type);
 
     case BUILT_IN_STRSPN:
-      return fold_builtin_strspn (loc, expr, arg0, arg1);
+      return fold_builtin_strspn (loc, expr, arg0, arg1, type);
 
     case BUILT_IN_STRCSPN:
-      return fold_builtin_strcspn (loc, expr, arg0, arg1);
+      return fold_builtin_strcspn (loc, expr, arg0, arg1, type);
 
     case BUILT_IN_STRPBRK:
       return fold_builtin_strpbrk (loc, expr, arg0, arg1, type);
@@ -11304,7 +11304,7 @@ fold_builtin_strpbrk (location_t loc, tree, tree s1, tree s2, tree type)
    form of the builtin function call.  */
 
 static tree
-fold_builtin_strspn (location_t loc, tree expr, tree s1, tree s2)
+fold_builtin_strspn (location_t loc, tree expr, tree s1, tree s2, tree type)
 {
   if (!validate_arg (s1, POINTER_TYPE)
       || !validate_arg (s2, POINTER_TYPE))
@@ -11320,8 +11320,7 @@ fold_builtin_strspn (location_t loc, tree expr, tree s1, tree s2)
   if ((p1 && *p1 == '\0') || (p2 && *p2 == '\0'))
     /* Evaluate and ignore both arguments in case either one has
        side-effects.  */
-    return omit_two_operands_loc (loc, size_type_node, size_zero_node,
-				  s1, s2);
+    return omit_two_operands_loc (loc, type, size_zero_node, s1, s2);
   return NULL_TREE;
 }
 
@@ -11344,7 +11343,7 @@ fold_builtin_strspn (location_t loc, tree expr, tree s1, tree s2)
    form of the builtin function call.  */
 
 static tree
-fold_builtin_strcspn (location_t loc, tree expr, tree s1, tree s2)
+fold_builtin_strcspn (location_t loc, tree expr, tree s1, tree s2, tree type)
 {
   if (!validate_arg (s1, POINTER_TYPE)
       || !validate_arg (s2, POINTER_TYPE))
@@ -11360,8 +11359,7 @@ fold_builtin_strcspn (location_t loc, tree expr, tree s1, tree s2)
     {
       /* Evaluate and ignore argument s2 in case it has
 	 side-effects.  */
-      return omit_one_operand_loc (loc, TREE_TYPE (expr),
-				   size_zero_node, s2);
+      return omit_one_operand_loc (loc, type, size_zero_node, s2);
     }
 
   /* If the second argument is "", return __builtin_strlen(s1).  */
@@ -11375,7 +11373,7 @@ fold_builtin_strcspn (location_t loc, tree expr, tree s1, tree s2)
       if (!fn)
 	return NULL_TREE;
 
-      return fold_convert_loc (loc, TREE_TYPE (expr),
+      return fold_convert_loc (loc, type,
 			       build_call_expr_loc (loc, fn, 1, s1));
     }
   return NULL_TREE;