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c++: Invisible refs are not restrict [PR97474]

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In this testcase, we refer to the a parameter through a reference in its own
member, which we asserted couldn't happen by marking the parameter as
'restrict'.  This assumption could also be broken if the address escapes
from the constructor.

gcc/cp/ChangeLog:

	PR c++/97474
	* call.c (type_passed_as): Don't mark invisiref restrict.

gcc/testsuite/ChangeLog:

	PR c++/97474
	* g++.dg/torture/pr97474.C: New test.
This commit is contained in:
Jason Merrill 2021-01-26 16:04:24 -05:00
parent a4dfd0f089
commit 96253f069e
2 changed files with 29 additions and 5 deletions
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6
gcc/cp/call.c
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@ -8263,11 +8263,7 @@ type_passed_as (tree type)
{
/* Pass classes with copy ctors by invisible reference. */
if (TREE_ADDRESSABLE (type))
{
type = build_reference_type (type);
/* There are no other pointers to this temporary. */
type = cp_build_qualified_type (type, TYPE_QUAL_RESTRICT);
}
type = build_reference_type (type);
else if (targetm.calls.promote_prototypes (NULL_TREE)
&& INTEGRAL_TYPE_P (type)
&& COMPLETE_TYPE_P (type)

28
gcc/testsuite/g++.dg/torture/pr97474.C Normal file
View File

@ -0,0 +1,28 @@
// PR c++/97474
// { dg-do run }
extern "C" int printf (const char *, ...);
extern "C" void abort ();
struct A {
int a;
int& b;
A(int x) : a(x), b(a) {}
A(const A& other) : a(other.a), b(a) {}
A() : a(0), b(a) {}
};
int foo(A a) {
a.a *= a.b;
return a.b;
}
int main() {
A a(3);
int r = foo (a);
if (r != 9)
abort ();
}