Commit 30a52a6d by Jason Merrill Committed by Jason Merrill

PR c++/64372 - CWG 1560, gratuitous lvalue-rvalue conversion in ?:

	* call.c (build_conditional_expr_1): Don't force_rvalue when one arm
	is a throw-expression.

From-SVN: r260272
parent 27560569
2018-05-15 Jason Merrill <jason@redhat.com>
PR c++/64372 - CWG 1560, gratuitous lvalue-rvalue conversion in ?:
* call.c (build_conditional_expr_1): Don't force_rvalue when one arm
is a throw-expression.
2018-05-15 Paolo Carlini <paolo.carlini@oracle.com>
* cp-tree.h (DECL_MAYBE_IN_CHARGE_CDTOR_P): New.
......
......@@ -4969,56 +4969,33 @@ build_conditional_expr_1 (location_t loc, tree arg1, tree arg2, tree arg3,
arg3_type = unlowered_expr_type (arg3);
if (VOID_TYPE_P (arg2_type) || VOID_TYPE_P (arg3_type))
{
/* Do the conversions. We don't these for `void' type arguments
since it can't have any effect and since decay_conversion
does not handle that case gracefully. */
if (!VOID_TYPE_P (arg2_type))
arg2 = decay_conversion (arg2, complain);
if (!VOID_TYPE_P (arg3_type))
arg3 = decay_conversion (arg3, complain);
arg2_type = TREE_TYPE (arg2);
arg3_type = TREE_TYPE (arg3);
/* [expr.cond]
One of the following shall hold:
--The second or the third operand (but not both) is a
throw-expression (_except.throw_); the result is of the
type of the other and is an rvalue.
throw-expression (_except.throw_); the result is of the type
and value category of the other.
--Both the second and the third operands have type void; the
result is of type void and is an rvalue.
We must avoid calling force_rvalue for expressions of type
"void" because it will complain that their value is being
used. */
result is of type void and is a prvalue. */
if (TREE_CODE (arg2) == THROW_EXPR
&& TREE_CODE (arg3) != THROW_EXPR)
{
if (!VOID_TYPE_P (arg3_type))
{
arg3 = force_rvalue (arg3, complain);
if (arg3 == error_mark_node)
return error_mark_node;
}
arg3_type = TREE_TYPE (arg3);
result_type = arg3_type;
is_glvalue = glvalue_p (arg3);
}
else if (TREE_CODE (arg2) != THROW_EXPR
&& TREE_CODE (arg3) == THROW_EXPR)
{
if (!VOID_TYPE_P (arg2_type))
{
arg2 = force_rvalue (arg2, complain);
if (arg2 == error_mark_node)
return error_mark_node;
}
arg2_type = TREE_TYPE (arg2);
result_type = arg2_type;
is_glvalue = glvalue_p (arg2);
}
else if (VOID_TYPE_P (arg2_type) && VOID_TYPE_P (arg3_type))
result_type = void_type_node;
{
result_type = void_type_node;
is_glvalue = false;
}
else
{
if (complain & tf_error)
......@@ -5037,7 +5014,6 @@ build_conditional_expr_1 (location_t loc, tree arg1, tree arg2, tree arg3,
return error_mark_node;
}
is_glvalue = false;
goto valid_operands;
}
/* [expr.cond]
......@@ -5155,10 +5131,6 @@ build_conditional_expr_1 (location_t loc, tree arg1, tree arg2, tree arg3,
&& same_type_p (arg2_type, arg3_type))
{
result_type = arg2_type;
if (processing_template_decl)
/* Let lvalue_kind know this was a glvalue. */
result_type = cp_build_reference_type (result_type, xvalue_p (arg2));
arg2 = mark_lvalue_use (arg2);
arg3 = mark_lvalue_use (arg3);
goto valid_operands;
......@@ -5352,6 +5324,13 @@ build_conditional_expr_1 (location_t loc, tree arg1, tree arg2, tree arg3,
return error_mark_node;
valid_operands:
if (processing_template_decl && is_glvalue)
{
/* Let lvalue_kind know this was a glvalue. */
tree arg = (result_type == arg2_type ? arg2 : arg3);
result_type = cp_build_reference_type (result_type, xvalue_p (arg));
}
result = build3_loc (loc, COND_EXPR, result_type, arg1, arg2, arg3);
/* If the ARG2 and ARG3 are the same and don't have side-effects,
......
// Core 1560
// { dg-do compile { target c++14 } }
struct A
{
A();
A(const A&) = delete;
};
void f(bool b)
{
A a;
b ? a : throw 42;
}
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