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PR c++/86608 - reading constexpr volatile variable.

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* constexpr.c (potential_constant_expression_1): Check want_rval
	instead of checking if we have a decl.
	* decl2.c (decl_maybe_constant_var_p): Don't consider volatile
	constexpr variables as maybe constant.

	* g++.dg/cpp0x/constexpr-volatile2.C: New test.
	* g++.dg/cpp0x/pr65327.C: Add dg-error.

From-SVN: r267030
This commit is contained in:
Marek Polacek 2018-12-11 18:53:03 +00:00 • committed by Marek Polacek
parent 6b9ef867ec
commit 3c393a2c01
6 changed files with 32 additions and 4 deletions
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8
gcc/cp/ChangeLog
View file

@ -1,3 +1,11 @@
2018-12-11 Marek Polacek <polacek@redhat.com>
PR c++/86608 - reading constexpr volatile variable.
* constexpr.c (potential_constant_expression_1): Check want_rval
instead of checking if we have a decl.
* decl2.c (decl_maybe_constant_var_p): Don't consider volatile
constexpr variables as maybe constant.
2018-12-11 Paolo Carlini <paolo.carlini@oracle.com>
* decl.c (grokvardecl): Add location_t parameter and use it

5
gcc/cp/constexpr.c
View file

@ -5476,10 +5476,11 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
available, so we don't bother with switch tracking. */
return true;
if (TREE_THIS_VOLATILE (t) && !DECL_P (t))
if (TREE_THIS_VOLATILE (t) && want_rval)
{
if (flags & tf_error)
error_at (loc, "expression %qE has side-effects", t);
error_at (loc, "lvalue-to-rvalue conversion of a volatile lvalue "
"%qE with type %qT", t, TREE_TYPE (t));
return false;
}
if (CONSTANT_CLASS_P (t))

2
gcc/cp/decl2.c
View file

@ -4313,7 +4313,7 @@ decl_maybe_constant_var_p (tree decl)
tree type = TREE_TYPE (decl);
if (!VAR_P (decl))
return false;
if (DECL_DECLARED_CONSTEXPR_P (decl))
if (DECL_DECLARED_CONSTEXPR_P (decl) && !TREE_THIS_VOLATILE (decl))
return true;
if (DECL_HAS_VALUE_EXPR_P (decl))
/* A proxy isn't constant. */

6
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,9 @@
2018-12-11 Marek Polacek <polacek@redhat.com>
PR c++/86608 - reading constexpr volatile variable.
* g++.dg/cpp0x/constexpr-volatile2.C: New test.
* g++.dg/cpp0x/pr65327.C: Add dg-error.
2018-12-11 Paolo Carlini <paolo.carlini@oracle.com>
* g++.dg/pr53037-4.C: Test the first two locations too.

13
gcc/testsuite/g++.dg/cpp0x/constexpr-volatile2.C Normal file
View file

@ -0,0 +1,13 @@
// PR c++/86608
// { dg-do compile { target c++11 } }
template<typename T, T v> struct X {};
int
main ()
{
static constexpr volatile int a = 3;
constexpr volatile int b = 2;
return (sizeof(X<decltype(a), a>) // { dg-error "lvalue-to-rvalue conversion of a volatile lvalue" }
+ sizeof(X<decltype(b), b>)); // { dg-error "lvalue-to-rvalue conversion of a volatile lvalue" }
}

2
gcc/testsuite/g++.dg/cpp0x/pr65327.C
View file

@ -15,4 +15,4 @@ constexpr volatile int
bar ()
{
return i;
}
} // { dg-error "lvalue-to-rvalue conversion of a volatile lvalue" }