On Tue, Jan 21, 2025 at 05:09:32PM -0500, Jason Merrill wrote:
> On 1/16/25 5:42 PM, Marek Polacek wrote:
> > On Wed, Jan 15, 2025 at 04:18:36PM -0500, Jason Merrill wrote:
> > > On 1/15/25 12:55 PM, Marek Polacek wrote:
> > > > On Wed, Jan 15, 2025 at 09:39:41AM -0500, Jason Merrill wrote:
> > > > > On 11/15/24 9:08 AM, Marek Polacek wrote:
> > > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > > > >
> > > > > > -- >8 --
> > > > > > The error here should also check that we aren't nested in another
> > > > > > lambda; in it, at_function_scope_p() will be false.
> > > > > >
> > > > > > PR c++/117602
> > > > > >
> > > > > > gcc/cp/ChangeLog:
> > > > > >
> > > > > > * parser.cc (cp_parser_lambda_introducer): Check if we're in a
> > > > > > lambda
> > > > > > before emitting the error about a non-local lambda with
> > > > > > a capture-default.
> > > > > >
> > > > > > gcc/testsuite/ChangeLog:
> > > > > >
> > > > > > * g++.dg/cpp2a/lambda-uneval19.C: New test.
> > > > > > ---
> > > > > > gcc/cp/parser.cc | 5 ++++-
> > > > > > gcc/testsuite/g++.dg/cpp2a/lambda-uneval19.C | 14 ++++++++++++++
> > > > > > 2 files changed, 18 insertions(+), 1 deletion(-)
> > > > > > create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-uneval19.C
> > > > > >
> > > > > > diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> > > > > > index 07b12224615..dc79ff42a3b 100644
> > > > > > --- a/gcc/cp/parser.cc
> > > > > > +++ b/gcc/cp/parser.cc
> > > > > > @@ -11611,7 +11611,10 @@ cp_parser_lambda_introducer (cp_parser*
> > > > > > parser, tree lambda_expr)
> > > > > > cp_lexer_consume_token (parser->lexer);
> > > > > > first = false;
> > > > > > - if (!(at_function_scope_p () || parsing_nsdmi ()))
> > > > > > + if (!(at_function_scope_p ()
> > > > > > + || parsing_nsdmi ()
> > > > > > + || (current_class_type
> > > > > > + && LAMBDA_TYPE_P (current_class_type))))
> > > > >
> > > > > How about using current_nonlambda_scope () instead of
> > > > > at_function_scope_p
> > > > > ()?
> > > >
> > > > I think I remember not using that because current_nonlambda_scope() will
> > > > give us a namespace_decl :: for non-local stuff so it won't be null. Do
> > > > you still prefer that (checking the result of current_nonlambda_scope())
> > > > to what I did in my patch?
> > >
> > > I think so, your change looks to be true for lambdas outside function
> > > scope
> > > as well.
> >
> > I think it works correctly for both
> >
> > auto x = [&]() { // error
> > [&]() { };
> > };
> > auto x2 = []() {
> > [&]() { };
> > };
> >
> > but current_nonlambda_scope () will return '::' for the nested lambdas too.
> > Am I missing something?
>
> Ah, good point. But it doesn't work correctly for an adjustment to the PR
> testcase; with your patch the following is wrongly accepted:
>
> auto x = [](decltype([&]{})){};
You're right.
> Perhaps current_scope should look through closure types, so
> at_function_scope_p gives the right answer?
I've tried but then other code breaks because it doesn't expect
current_scope to behave like that.
So how about this one? It seems very safe.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
The error here should also check that we aren't nested in another
lambda; in it, at_function_scope_p() will be false.
PR c++/117602
gcc/cp/ChangeLog:
* cp-tree.h (current_nonlambda_scope): Add a default argument.
* lambda.cc (current_nonlambda_scope): New bool parameter. Use it.
* parser.cc (cp_parser_lambda_introducer): Use current_nonlambda_scope
to check if the lambda is non-local.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/lambda-uneval21.C: New test.
---
gcc/cp/cp-tree.h | 2 +-
gcc/cp/lambda.cc | 8 +++--
gcc/cp/parser.cc | 3 +-
gcc/testsuite/g++.dg/cpp2a/lambda-uneval21.C | 32 ++++++++++++++++++++
4 files changed, 40 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-uneval21.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 0eb3e8531c5..5e8aefc1289 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -8097,7 +8097,7 @@ extern void maybe_generic_this_capture (tree,
tree);
extern tree maybe_resolve_dummy (tree, bool);
extern tree current_nonlambda_function (void);
extern tree nonlambda_method_basetype (void);
-extern tree current_nonlambda_scope (void);
+extern tree current_nonlambda_scope (bool = false);
extern tree current_lambda_expr (void);
extern bool generic_lambda_fn_p (tree);
extern tree do_dependent_capture (tree, bool = false);
diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc
index acb7208fd18..5593636eaf8 100644
--- a/gcc/cp/lambda.cc
+++ b/gcc/cp/lambda.cc
@@ -1045,15 +1045,17 @@ nonlambda_method_basetype (void)
}
}
-/* Like current_scope, but looking through lambdas. */
+/* Like current_scope, but looking through lambdas. If ONLY_SKIP_CLOSURES_P,
+ only look through closure types. */
tree
-current_nonlambda_scope (void)
+current_nonlambda_scope (bool only_skip_closures_p/*=false*/)
{
tree scope = current_scope ();
for (;;)
{
- if (TREE_CODE (scope) == FUNCTION_DECL
+ if (!only_skip_closures_p
+ && TREE_CODE (scope) == FUNCTION_DECL
&& LAMBDA_FUNCTION_P (scope))
{
scope = CP_TYPE_CONTEXT (DECL_CONTEXT (scope));
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 24322817f3e..03010089c3c 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -11877,7 +11877,8 @@ cp_parser_lambda_introducer (cp_parser* parser, tree
lambda_expr)
cp_lexer_consume_token (parser->lexer);
first = false;
- if (!(at_function_scope_p () || parsing_nsdmi ()))
+ tree scope = current_nonlambda_scope (/*only_skip_closures_p=*/true);
+ if (TREE_CODE (scope) != FUNCTION_DECL && !parsing_nsdmi ())
error ("non-local lambda expression cannot have a capture-default");
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-uneval21.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-uneval21.C
new file mode 100644
index 00000000000..d3ea3acf52d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-uneval21.C
@@ -0,0 +1,32 @@
+// PR c++/117602
+// { dg-do compile { target c++20 } }
+
+auto x1 = [](decltype([&]{})){}; // { dg-error "non-local lambda" }
+
+auto x2 = [&]() { // { dg-error "non-local lambda" }
+ [&]() { };
+};
+
+auto x3 = []() {
+ [&]() { };
+};
+
+auto x4 = []() {
+ []() { };
+};
+
+auto x5 = [&]() { // { dg-error "non-local lambda" }
+ []() { };
+};
+
+void
+g ()
+{
+ [&](decltype([&](decltype([=](decltype([&](decltype([&]() {})) {})) {}))
{})){};
+ [&](decltype([&](decltype([&](decltype([&](decltype([&]() {})) {})) {}))
{})){};
+ [=](decltype([=](decltype([=](decltype([=](decltype([&]() {})) {})) {}))
{})){};
+
+ [=]() {
+ [&]() { };
+ };
+}
base-commit: 0bb3223097e5ced4f9a13d18c6c65f2a9496437e
--
2.48.1
