Since the patch for PR103408, the template parameters for the lambda in this
test have level 1 instead of 2, and we were treating null template args as 1
level of arguments, so tsubst_template_parms decided it had nothing to do.
Fixed by distinguishing between <> and no args at all, which is what we have
in our "substitution" in a requires-expression.
Tested x86_64-pc-linux-gnu, applying to trunk.
PR c++/105541
gcc/cp/ChangeLog:
* cp-tree.h (TMPL_ARGS_DEPTH): 0 for null args.
* parser.cc (cp_parser_enclosed_template_argument_list):
Use 0-length TREE_VEC for <>.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/lambda-requires1.C: New test.
---
gcc/cp/cp-tree.h | 12 +++++++-----
gcc/cp/parser.cc | 5 ++++-
gcc/testsuite/g++.dg/cpp2a/lambda-requires1.C | 4 ++++
3 files changed, 15 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-requires1.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index e16b8d70846..b6961a796af 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3771,11 +3771,13 @@ struct GTY(()) lang_decl {
/* The depth of a template argument vector. When called directly by
the parser, we use a TREE_LIST rather than a TREE_VEC to represent
- template arguments. In fact, we may even see NULL_TREE if there
- are no template arguments. In both of those cases, there is only
- one level of template arguments. */
-#define TMPL_ARGS_DEPTH(NODE) \
- (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (NODE) ? TREE_VEC_LENGTH (NODE) : 1)
+ template arguments. In that case, there is only one level of template
+ arguments. We may even see NULL_TREE if there are 0 levels of
+ template arguments, as in cp_parser_requires_expression. */
+#define TMPL_ARGS_DEPTH(NODE) \
+ ((NODE) == NULL_TREE ? 0 \
+ : TMPL_ARGS_HAVE_MULTIPLE_LEVELS (NODE) ? TREE_VEC_LENGTH (NODE) \
+ : 1)
/* The LEVELth level of the template ARGS. The outermost level of
args is level 1, not level 0. */
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 4ed9feaa427..d09d5b7c8b7 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -32151,7 +32151,10 @@ cp_parser_enclosed_template_argument_list (cp_parser*
parser)
|| cp_lexer_next_token_is (parser->lexer, CPP_RSHIFT)
|| cp_lexer_next_token_is (parser->lexer, CPP_GREATER_EQ)
|| cp_lexer_next_token_is (parser->lexer, CPP_RSHIFT_EQ))
- arguments = NULL_TREE;
+ {
+ arguments = make_tree_vec (0);
+ SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT (arguments, 0);
+ }
else
arguments = cp_parser_template_argument_list (parser);
/* Look for the `>' that ends the template-argument-list. If we find
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-requires1.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-requires1.C
new file mode 100644
index 00000000000..fdfdaebcf6a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-requires1.C
@@ -0,0 +1,4 @@
+// PR c++/105541
+// { dg-do compile { target c++20 } }
+
+static_assert(requires { []<typename T>{}; });
base-commit: 4dc86f716fe6087f1cf786d69c0c6f3f5af810f0
--
2.27.0
