[gcc(refs/users/marxin/heads/opt-parse-enum-sanity)] c++: Fix C++20 variadic lambda init-capture grammar.
Martin Liska
marxin@gcc.gnu.org
Tue Mar 17 15:49:12 GMT 2020
https://gcc.gnu.org/g:32b8f5df9f05426c82c6de1acaf9ca4aec68039d
commit 32b8f5df9f05426c82c6de1acaf9ca4aec68039d
Author: Jason Merrill <jason@redhat.com>
Date: Sun Feb 23 20:52:41 2020 -0500
c++: Fix C++20 variadic lambda init-capture grammar.
The grammar for variadic init-capture was fixed at the Prague C++ meeting
where we finalized C++20.
gcc/cp/ChangeLog
2020-02-24 Jason Merrill <jason@redhat.com>
P0780R2: Resolve lambda init-capture pack grammar.
* parser.c (cp_parser_lambda_introducer): Expect &...x=y rather than
...&x=y.
Diff:
---
gcc/cp/ChangeLog | 6 ++++++
gcc/cp/parser.c | 15 +++++++++++++--
gcc/testsuite/g++.dg/cpp2a/lambda-pack-init4.C | 10 ++++++++++
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 8a3c9f77ad0..cc0f42dfda5 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-02-24 Jason Merrill <jason@redhat.com>
+
+ P0780R2: Resolve lambda init-capture pack grammar.
+ * parser.c (cp_parser_lambda_introducer): Expect &...x=y rather than
+ ...&x=y.
+
2020-02-22 Marek Polacek <polacek@redhat.com>
PR c++/93882
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index ee534b5db21..87ed2a3a648 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -10620,6 +10620,7 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
/* Record default capture mode. "[&" "[=" "[&," "[=," */
if (cp_lexer_next_token_is (parser->lexer, CPP_AND)
+ && !cp_lexer_nth_token_is (parser->lexer, 2, CPP_ELLIPSIS)
&& !cp_lexer_nth_token_is (parser->lexer, 2, CPP_NAME)
&& !cp_lexer_nth_token_is_keyword (parser->lexer, 2, RID_THIS))
LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (lambda_expr) = CPLD_REFERENCE;
@@ -10715,6 +10716,13 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
continue;
}
+ /* Remember whether we want to capture as a reference or not. */
+ if (cp_lexer_next_token_is (parser->lexer, CPP_AND))
+ {
+ capture_kind = BY_REFERENCE;
+ cp_lexer_consume_token (parser->lexer);
+ }
+
bool init_pack_expansion = false;
location_t ellipsis_loc = UNKNOWN_LOCATION;
if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS))
@@ -10727,9 +10735,12 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
init_pack_expansion = true;
}
- /* Remember whether we want to capture as a reference or not. */
- if (cp_lexer_next_token_is (parser->lexer, CPP_AND))
+ /* Early C++20 drafts had ...& instead of &...; be forgiving. */
+ if (init_pack_expansion && capture_kind != BY_REFERENCE
+ && cp_lexer_next_token_is (parser->lexer, CPP_AND))
{
+ pedwarn (cp_lexer_peek_token (parser->lexer)->location,
+ 0, "%<&%> should come before %<...%>");
capture_kind = BY_REFERENCE;
cp_lexer_consume_token (parser->lexer);
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-pack-init4.C b/gcc/testsuite/g++.dg/cpp2a/lambda-pack-init4.C
new file mode 100644
index 00000000000..e7c815b92d4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-pack-init4.C
@@ -0,0 +1,10 @@
+// P2095R0
+// { dg-do compile { target c++2a } }
+// { dg-options "" }
+
+template <class... T>
+void f(T... t)
+{
+ [&...x=t]{};
+ [...&x=t]{}; // { dg-warning "7:&" }
+}
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