Regtested on x86_64-pc-linux-gnu.
This patch fixes a few ICEs related to requires-clauses in lambdas like:
```
auto f = [](auto x) requires(
auto f = [](auto x) requires(foo;) {}
auto f = [](auto x) requires {} {}
```
and many other variations that caused ICEs.
However, it doesn't fix the rejects-valid of the testcase from the bug
report.
The main issue missing is that when we get to grokmethod (and then
grokfndecl) we aren't able to create TEMPLATE_INFO for this lambda.
I tried a few different fixes but I couldn't stop the call to
cp_parser_requires_clause_opt from ruining the template info of this
lambda (it is quite shaky when it comes to processing_template_decl).
With some changes around the code after grokmethod that attempts to fix
the lambda with calls to finish_fully_implicit_template and others (like
potentially moving it before grokmethod?), or maybe being able to save
some state before calling cp_parser_requires_clause_opt, we might be
able to later correctly create TEMPLATE_INFO.
Should I open a new BZ for this rejects-valid and associate this patch
to that? It's an improvement to having a bunch of ICEs around
requires-clauses but doesn't fix PR123080 entirely.
-- >8 --
When parsing a lambda with a trailing requires-clause, calling
cp_parser_requires_clause_opt really confuses generic lambda parsing
when implicit template parameters are involved.
This fixes a few ICEs related to invalid/valid requires clauses in
lambdas with auto parameters.
PR c++/123080
gcc/cp/ChangeLog:
* parser.cc (cp_parser_lambda_declarator_opt): add cleanup for
fully_implicit_function_template_p before parsing
trailing_requires_clause.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/lambda-requires6.C: New test.
Signed-off-by: Egas Ribeiro <[email protected]>
---
gcc/cp/parser.cc | 2 ++
gcc/testsuite/g++.dg/cpp2a/lambda-requires6.C | 6 ++++++
2 files changed, 8 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-requires6.C
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index b3bf0703d3d..72ff05c20a3 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -12746,6 +12746,8 @@ cp_parser_lambda_declarator_opt (cp_parser* parser,
tree lambda_expr,
if (has_param_list)
{
+ auto cleanup
+ = make_temp_override (parser->fully_implicit_function_template_p);
/* Parse optional trailing requires clause. */
trailing_requires_clause = cp_parser_requires_clause_opt (parser, false);
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-requires6.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-requires6.C
new file mode 100644
index 00000000000..d1f4329a993
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-requires6.C
@@ -0,0 +1,6 @@
+// PR c++/123080
+// { dg-do compile { target c++20 } }
+// { dg-xfail-if "PR123080 - rejects valid" *-*-* }
+template<typename T> struct type_identity { using type = T; };
+auto f = [](auto x) requires requires { typename
type_identity<decltype(x)>::type(0); } {};
+int main() { f(0); }
--
2.52.0
