Hi!
As the testcase shows, we are silently accepting writes into const
variables, because the type generic builtins don't have a prototype.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2019-05-27 Jakub Jelinek <ja...@redhat.com>
PR c/90628
* c-common.c (check_builtin_function_arguments)
<case BUILTIN_*_OVERFLOW>: Diagnose pointer to const qualified integer
as last argument.
* c-c++-common/builtin-arith-overflow-3.c: New test.
--- gcc/c-family/c-common.c.jj 2019-05-21 16:16:48.068973678 +0200
+++ gcc/c-family/c-common.c 2019-05-27 10:46:25.525968739 +0200
@@ -5995,6 +5995,13 @@ check_builtin_function_arguments (locati
"has pointer to boolean type", fndecl);
return false;
}
+ else if (TYPE_READONLY (TREE_TYPE (TREE_TYPE (args[2]))))
+ {
+ error_at (ARG_LOCATION (2), "argument 3 in call to function %qE "
+ "has pointer type to %<const%> qualified integer",
+ fndecl);
+ return false;
+ }
return true;
}
return false;
--- gcc/testsuite/c-c++-common/builtin-arith-overflow-3.c.jj 2019-05-27
10:51:46.829710217 +0200
+++ gcc/testsuite/c-c++-common/builtin-arith-overflow-3.c 2019-05-27
10:53:10.972330933 +0200
@@ -0,0 +1,42 @@
+/* PR c/90628 */
+/* { dg-do compile } */
+
+const int a = 1, b = 2, c = 3;
+const long d = 4, e = 5, f = 6;
+const long long g = 7, h = 8, i = 9;
+
+void
+f1 ()
+{
+ __builtin_add_overflow (a, b, &c); /* { dg-error "argument 3 in call to
function '__builtin_add_overflow' has pointer type to 'const' qualified
integer" } */
+}
+
+void
+f2 ()
+{
+ __builtin_sub_overflow (d, e, &f); /* { dg-error "argument 3 in call to
function '__builtin_sub_overflow' has pointer type to 'const' qualified
integer" } */
+}
+
+void
+f3 ()
+{
+ __builtin_mul_overflow (g, h, &i); /* { dg-error "argument 3 in call to
function '__builtin_mul_overflow' has pointer type to 'const' qualified
integer" } */
+}
+
+void
+f4 ()
+{
+ __builtin_sadd_overflow (a, b, &c); /* { dg-warning "passing argument 3 of
'__builtin_sadd_overflow' discards 'const' qualifier from pointer target type"
"" { target c } } */
+} /* { dg-error "invalid conversion from 'const int\\*' to 'int\\*'" "" {
target c++ } .-1 } */
+
+void
+f5 ()
+{
+ __builtin_ssubl_overflow (d, e, &f); /* { dg-warning "passing argument 3 of
'__builtin_ssubl_overflow' discards 'const' qualifier from pointer target type"
"" { target c } } */
+} /* { dg-error "invalid conversion from 'const long int\\*' to 'long
int\\*'" "" { target c++ } .-1 } */
+
+void
+f6 ()
+{
+ __builtin_smulll_overflow (g, h, &i); /* { dg-warning "passing
argument 3 of '__builtin_smulll_overflow' discards 'const' qualifier from
pointer target type" "" { target c } } */
+} /* { dg-error "invalid conversion from 'const long long int\\*' to
'long long int\\*'" "" { target c++ } .-1 } */
Jakub
