From: Patrick Palka <ppalka@redhat.com>
To: gcc-patches@gcc.gnu.org
Subject: [PATCH] c++: consider built-in operator candidates first
Date: Mon, 20 Sep 2021 12:46:08 -0400 [thread overview]
Message-ID: <20210920164608.2740792-1-ppalka@redhat.com> (raw)
During operator overload resolution, we currently consider non-member
candidates before built-in candidates. This didn't make a difference
before r12-3346, but after this change add_candidates will avoid
computing excess argument conversions if we've already seen a strictly
viable candidate, so it's better to consider built-in candidates first.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
gcc/cp/ChangeLog:
* call.c (add_operator_candidates): Consider built-in operator
candidates before considering non-member candidates.
gcc/testsuite/ChangeLog:
* g++.dg/template/conv17.C: Extend test.
---
gcc/cp/call.c | 13 +++++++------
gcc/testsuite/g++.dg/template/conv17.C | 7 +++++++
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index c5601d96ab8..c0da083758f 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6321,7 +6321,6 @@ add_operator_candidates (z_candidate **candidates,
vec<tree, va_gc> *arglist,
int flags, tsubst_flags_t complain)
{
- z_candidate *start_candidates = *candidates;
bool ismodop = code2 != ERROR_MARK;
tree fnname = ovl_op_identifier (ismodop, ismodop ? code2 : code);
@@ -6333,6 +6332,12 @@ add_operator_candidates (z_candidate **candidates,
if (rewritten && code != EQ_EXPR && code != SPACESHIP_EXPR)
flags &= ~LOOKUP_REWRITTEN;
+ /* Add built-in candidates to the candidate set. The standard says to
+ rewrite built-in candidates, too, but there's no point. */
+ if (!rewritten)
+ add_builtin_candidates (candidates, code, code2, fnname, arglist,
+ flags, complain);
+
bool memonly = false;
switch (code)
{
@@ -6352,6 +6357,7 @@ add_operator_candidates (z_candidate **candidates,
/* Add namespace-scope operators to the list of functions to
consider. */
+ z_candidate *start_candidates = *candidates;
if (!memonly)
{
tree fns = lookup_name (fnname, LOOK_where::BLOCK_NAMESPACE);
@@ -6423,11 +6429,6 @@ add_operator_candidates (z_candidate **candidates,
if (!rewritten)
{
- /* The standard says to rewrite built-in candidates, too,
- but there's no point. */
- add_builtin_candidates (candidates, code, code2, fnname, arglist,
- flags, complain);
-
/* Maybe add C++20 rewritten comparison candidates. */
tree_code rewrite_code = ERROR_MARK;
if (cxx_dialect >= cxx20
diff --git a/gcc/testsuite/g++.dg/template/conv17.C b/gcc/testsuite/g++.dg/template/conv17.C
index f0f10f2ef4f..87ecefb8de3 100644
--- a/gcc/testsuite/g++.dg/template/conv17.C
+++ b/gcc/testsuite/g++.dg/template/conv17.C
@@ -61,3 +61,10 @@ concept E = requires { T().h(nullptr); };
static_assert(!E<C>);
#endif
+
+// Verify that the strictly viable built-in operator+ candidate precludes
+// us from computing all argument conversions for the below non-strictly
+// viable non-member candidate.
+enum N { n };
+int operator+(N&, B);
+int f = n + 42;
--
2.33.0.363.g4c719308ce
next reply other threads:[~2021-09-20 16:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 16:46 Patrick Palka [this message]
2021-09-20 18:42 ` Jason Merrill
2021-09-20 19:32 ` Patrick Palka
2021-09-20 19:56 ` Jason Merrill
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