Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
for trunk?
-- >8 --
Here we're tripping over the assert in extract_locals_r which enforces
that an extra-args tree appearing inside another extra-args tree doesn't
actually have extra args. This invariant no longer always holds for
lambdas (which recently gained the extra-args mechanism), but it should
be safe to just disable the assert for them since cp_walk_subtrees doesn't
walk LAMBDA_EXPR_EXTRA_ARGS and so should be immune to the PR114303 issue
for now.
PR c++/117054
gcc/cp/ChangeLog:
* pt.cc (extract_locals_r): Disable tree_extra_args assert
for LAMBDA_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/lambda-targ9.C: New test.
---
gcc/cp/pt.cc | 7 ++++++-
gcc/testsuite/g++.dg/cpp2a/lambda-targ9.C | 16 ++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-targ9.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index c7cbf6df26c..b90447ae6a2 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -13479,7 +13479,12 @@ extract_locals_r (tree *tp, int *walk_subtrees, void
*data_)
outermost tree. Nested *_EXTRA_ARGS should naturally be empty since
the outermost (extra-args) tree will intercept any substitution before
a nested tree can. */
- gcc_checking_assert (tree_extra_args (*tp) == NULL_TREE);
+ gcc_checking_assert (tree_extra_args (*tp) == NULL_TREE
+ /* Except a lambda nested inside an extra-args tree
+ can have extra args if we deferred partial
+ substitution into it at template parse time. But
+ we don't walk LAMBDA_EXPR_EXTRA_ARGS anyway. */
+ || TREE_CODE (*tp) == LAMBDA_EXPR);
if (TREE_CODE (*tp) == DECL_EXPR)
{
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-targ9.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-targ9.C
new file mode 100644
index 00000000000..00dd4b2406e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-targ9.C
@@ -0,0 +1,16 @@
+// PR c++/117054
+// { dg-do compile { target c++20 } }
+
+template<auto = [] {}>
+constexpr bool a = true;
+
+template<typename>
+void f() {
+ [](auto) {
+ if constexpr (a<>) {}
+ };
+}
+
+int main() {
+ f<int>();
+}
--
2.47.0.72.gef8ce8f3d4
