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Re: C++ PATCH for c++/89686 - mixing init-capture and simple-capture in lambda
On Tue, Mar 12, 2019 at 04:07:56PM -0400, Jason Merrill wrote:
> On 3/12/19 3:59 PM, Marek Polacek wrote:
> > As Barry explained in the PR, lambda capture is one of
> >
> > simple-capture ...[opt]
> > ...[opt] init-capture
> >
> > where init-capture requires an initializer. Here we have
> >
> > [...xs...]
> >
> > which is ill-formed as it's mingling both of these.
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk? Or should I defer to GCC
> > 10?
> >
> > 2019-03-12 Marek Polacek <polacek@redhat.com>
> >
> > PR c++/89686 - mixing init-capture and simple-capture in lambda.
> > * parser.c (cp_parser_lambda_introducer): Give error when combining
> > init-capture and simple-capture.
> >
> > * g++.dg/cpp2a/lambda-pack-init2.C: New test.
> >
> > diff --git gcc/cp/parser.c gcc/cp/parser.c
> > index f95111169ed..d5d8f364752 100644
> > --- gcc/cp/parser.c
> > +++ gcc/cp/parser.c
> > @@ -10721,6 +10721,15 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
> > {
> > cp_lexer_consume_token (parser->lexer);
> > capture_init_expr = make_pack_expansion (capture_init_expr);
> > + if (init_pack_expansion)
> > + {
> > + /* We'd already seen '...' so we were expecting an
> > + init-capture. But we just saw another '...' which
> > + would imply a simple-capture. */
> > + error_at (capture_token->location,
> > + "combining init-capture and simple-capture");
>
> That diagnostic seems a bit obscure, how about something like "too many
> %<...%> in lambda capture"?
Yup, sounds better.
> Or perhaps check to see if there's an initializer after the ..., and
> complain about the second ... if so, or the first ... if not.
I tried but we already give diagnostic for [...xs=xs...] or [...xs=...xs]
and similar. But let's at least use a proper location for the '...'.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2019-03-12 Marek Polacek <polacek@redhat.com>
PR c++/89686 - mixing init-capture and simple-capture in lambda.
* parser.c (cp_parser_lambda_introducer): Give error when combining
init-capture and simple-capture.
* g++.dg/cpp2a/lambda-pack-init2.C: New test.
diff --git gcc/cp/parser.c gcc/cp/parser.c
index f95111169ed..69294e20191 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -10719,8 +10719,17 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS))
{
+ location_t eloc = cp_lexer_peek_token (parser->lexer)->location;
cp_lexer_consume_token (parser->lexer);
capture_init_expr = make_pack_expansion (capture_init_expr);
+ if (init_pack_expansion)
+ {
+ /* We'd already seen '...' so we were expecting an
+ init-capture. But we just saw another '...' which
+ would imply a simple-capture. */
+ error_at (eloc, "too many %<...%> in lambda capture");
+ continue;
+ }
}
}
diff --git gcc/testsuite/g++.dg/cpp2a/lambda-pack-init2.C gcc/testsuite/g++.dg/cpp2a/lambda-pack-init2.C
new file mode 100644
index 00000000000..cd31f3296e1
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp2a/lambda-pack-init2.C
@@ -0,0 +1,19 @@
+// PR c++/89686
+// { dg-do compile { target c++2a } }
+
+template <typename... Ts>
+void foo(Ts... xs)
+{
+ int i = 10;
+ [...xs...]{}(); // { dg-error "too many ..... in lambda capture" }
+ [xs...]{}();
+ [...xs=xs]{}();
+ [i, ...xs...]{}(); // { dg-error "too many ..... in lambda capture" }
+ [i, xs...]{}();
+ [i, ...xs=xs]{}();
+}
+
+int main()
+{
+ foo(0, 1, 2);
+}