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c++: Fix up CONSTRUCTOR_PLACEHOLDER_BOUNDARY handling [PR105256]

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The CONSTRUCTOR_PLACEHOLDER_BOUNDARY bit is supposed to separate
PLACEHOLDER_EXPRs that should be replaced by one object or subobjects of it
(variable, TARGET_EXPR slot, ...) from other PLACEHOLDER_EXPRs that should
be replaced by different objects or subobjects.
The bit is set when finding PLACEHOLDER_EXPRs inside of a CONSTRUCTOR, not
looking into nested CONSTRUCTOR_PLACEHOLDER_BOUNDARY ctors, and we prevent
elision of TARGET_EXPRs (through TARGET_EXPR_NO_ELIDE) whose initializer
is a CONSTRUCTOR_PLACEHOLDER_BOUNDARY ctor.  The following testcase ICEs
though, we don't replace the placeholders in there at all, because
CONSTRUCTOR_PLACEHOLDER_BOUNDARY isn't set on the TARGET_EXPR_INITIAL
ctor, but on a ctor nested in such a ctor.  replace_placeholders should be
run on the whole TARGET_EXPR slot.

So, the following patch fixes it by moving the CONSTRUCTOR_PLACEHOLDER_BOUNDARY
bit from nested CONSTRUCTORs to the CONSTRUCTOR containing those (but only
if it is closely nested, if there is some other tree sandwiched in between,
it doesn't do it).

2022-04-19  Jakub Jelinek  <jakub@redhat.com>

	PR c++/105256
	* typeck2.cc (process_init_constructor_array,
	process_init_constructor_record, process_init_constructor_union): Move
	CONSTRUCTOR_PLACEHOLDER_BOUNDARY flag from CONSTRUCTOR elements to the
	containing CONSTRUCTOR.

	* g++.dg/cpp0x/pr105256.C: New test.
This commit is contained in:
Jakub Jelinek 2022-04-19 18:27:41 +02:00
parent 353434b65e
commit eb03e42459
2 changed files with 49 additions and 0 deletions
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31
gcc/cp/typeck2.cc
View file

@ -1515,6 +1515,14 @@ process_init_constructor_array (tree type, tree init, int nested, int flags,
strip_array_types (TREE_TYPE (ce->value)))));
picflags |= picflag_from_initializer (ce->value);
/* Propagate CONSTRUCTOR_PLACEHOLDER_BOUNDARY to outer
CONSTRUCTOR. */
if (TREE_CODE (ce->value) == CONSTRUCTOR
&& CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ce->value))
{
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (init) = 1;
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ce->value) = 0;
}
}
/* No more initializers. If the array is unbounded, we are done. Otherwise,
@ -1560,6 +1568,14 @@ process_init_constructor_array (tree type, tree init, int nested, int flags,
}
picflags |= picflag_from_initializer (next);
/* Propagate CONSTRUCTOR_PLACEHOLDER_BOUNDARY to outer
CONSTRUCTOR. */
if (TREE_CODE (next) == CONSTRUCTOR
&& CONSTRUCTOR_PLACEHOLDER_BOUNDARY (next))
{
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (init) = 1;
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (next) = 0;
}
if (len > i+1)
{
tree range = build2 (RANGE_EXPR, size_type_node,
@ -1754,6 +1770,13 @@ process_init_constructor_record (tree type, tree init, int nested, int flags,
if (fldtype != TREE_TYPE (field))
next = cp_convert_and_check (TREE_TYPE (field), next, complain);
picflags |= picflag_from_initializer (next);
/* Propagate CONSTRUCTOR_PLACEHOLDER_BOUNDARY to outer CONSTRUCTOR. */
if (TREE_CODE (next) == CONSTRUCTOR
&& CONSTRUCTOR_PLACEHOLDER_BOUNDARY (next))
{
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (init) = 1;
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (next) = 0;
}
CONSTRUCTOR_APPEND_ELT (v, field, next);
}
@ -1894,6 +1917,14 @@ process_init_constructor_union (tree type, tree init, int nested, int flags,
ce->value = massage_init_elt (TREE_TYPE (ce->index), ce->value, nested,
flags, complain);
/* Propagate CONSTRUCTOR_PLACEHOLDER_BOUNDARY to outer CONSTRUCTOR. */
if (ce->value
&& TREE_CODE (ce->value) == CONSTRUCTOR
&& CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ce->value))
{
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (init) = 1;
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ce->value) = 0;
}
return picflag_from_initializer (ce->value);
}

18
gcc/testsuite/g++.dg/cpp0x/pr105256.C Normal file
View file

@ -0,0 +1,18 @@
// PR c++/105256
// { dg-do compile { target c++11 } }
int bar (int &);
struct S {
struct T {
struct U {
int i = bar (i);
} u;
};
};
void
foo (S::T *p)
{
*p = {};
};