On 11/10/23 10:28, Patrick Palka wrote:
On Fri, 10 Nov 2023, Patrick Palka wrote:
On Thu, 9 Nov 2023, Jason Merrill wrote:
On 11/8/23 16:59, Patrick Palka wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
-- >8 --
Here when building up the non-dependent .* expression, we crash from
fold_convert on 'b.a' due to this (templated) COMPONENT_REF having an
IDENTIFIER_NODE instead of FIELD_DECL operand that middle-end routines
expect. Like in r14-4899-gd80a26cca02587, this patch fixes this by
replacing the problematic piecemeal folding with a single call to
cp_fully_fold.
PR c++/112427
gcc/cp/ChangeLog:
* typeck2.cc (build_m_component_ref): Use cp_convert, build2 and
cp_fully_fold instead of fold_build_pointer_plus and fold_convert.
gcc/testsuite/ChangeLog:
* g++.dg/template/non-dependent29.C: New test.
---
gcc/cp/typeck2.cc | 5 ++++-
gcc/testsuite/g++.dg/template/non-dependent29.C | 13 +++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/template/non-dependent29.C
diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
index 309903afed8..208004221da 100644
--- a/gcc/cp/typeck2.cc
+++ b/gcc/cp/typeck2.cc
@@ -2378,7 +2378,10 @@ build_m_component_ref (tree datum, tree component,
tsubst_flags_t complain)
/* Build an expression for "object + offset" where offset is the
value stored in the pointer-to-data-member. */
ptype = build_pointer_type (type);
- datum = fold_build_pointer_plus (fold_convert (ptype, datum),
component);
+ datum = cp_convert (ptype, datum, complain);
+ datum = build2 (POINTER_PLUS_EXPR, ptype,
+ datum, convert_to_ptrofftype (component));
We shouldn't need to build the POINTER_PLUS_EXPR at all in template context.
OK with that change.
Hmm, that seems harmless at first glance, but I noticed
build_min_non_dep (called from build_x_binary_op in this case) is
careful to propagate TREE_SIDE_EFFECTS of the given tree, and so eliding
POINTER_PLUS_EXPR here could potentially mean that the tree we
ultimately return from build_x_binary_op when in a template context has
TREE_SIDE_EFFECTS not set when it used to. Shall we still elide the
POINTER_PLUS_EXPR in a template context despite this?
True, we would need build_min_non_dep to also get TREE_SIDE_EFFECTS from
the operands. That might be useful in general for similar situations?
I also note that convert_to_ptrofftype uses fold_convert, so the new
code could have the same problem if the pointer to member operand is
also a COMPONENT_REF.
Jason
