Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
-- >8 --
For a local variable initialized by a lambda:
auto f = []{};
The corresponding BLOCK_VARS contains the variable declaration first,
followed by the closure type declaration, consistent with the
syntactical order. This however means that a use of the closure type
appears (in the variable type/initializer) before the declaration of the
type. This ends up causing an ICE when streaming the BLOCK_VARS of f1
below because we stream (by value) the CONSTRUCTOR initializer of g1 --
which contains components of the closure type -- before we've streamed
the declaration defining the closure type. The following comment in
module.cc seems relevant:
/* We want to stream the type of a expression-like nodes /after/
we've streamed the operands. The type often contains (bits
of the) types of the operands, and with things like decltype
and noexcept in play, we really want to stream the decls
defining the type before we try and stream the type on its
own. Otherwise we can find ourselves trying to read in a
decl, when we're already partially reading in a component of
its type. And that's bad. */
This patch narrowly fixes this issue by special casing closure type
declarations in add_decl_to_level. (A loop is needed since there could
be multiple variable declarations with an unprocessed initializer in
light of structured bindings.)
PR c++/105322
gcc/cp/ChangeLog:
* name-lookup.cc (add_decl_to_level): When adding a closure
type declaration to a block scope, add it before rather than
after any variable declarations whose initializer we're still
processing.
gcc/testsuite/ChangeLog:
* g++.dg/modules/lambda-5_a.C: New test.
* g++.dg/modules/lambda-5_b.C: New test.
---
gcc/cp/name-lookup.cc | 19 ++++++++++++++++---
gcc/testsuite/g++.dg/modules/lambda-5_a.C | 23 +++++++++++++++++++++++
gcc/testsuite/g++.dg/modules/lambda-5_b.C | 10 ++++++++++
3 files changed, 49 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/modules/lambda-5_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/lambda-5_b.C
diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index a8b9229b29e..bb00baaf9f4 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -391,9 +391,22 @@ add_decl_to_level (cp_binding_level *b, tree decl)
gcc_assert (b->names != decl);
/* We build up the list in reverse order, and reverse it later if
- necessary. */
- TREE_CHAIN (decl) = b->names;
- b->names = decl;
+ necessary. If we're adding a lambda closure type to a block
+ scope as part of a local variable initializer, then make sure
+ we declare the type before the variable; modules expects that
+ we see a type declaration before a use of the type. */
+ tree *prev = &b->names;
+ if (b->kind == sk_block
+ && !processing_template_decl
+ && TREE_CODE (decl) == TYPE_DECL
+ && LAMBDA_TYPE_P (TREE_TYPE (decl)))
+ while (*prev && VAR_P (*prev)
+ && !DECL_EXTERNAL (*prev)
+ && !DECL_INITIALIZED_P (*prev))
+ prev = &TREE_CHAIN (*prev);
+
+ TREE_CHAIN (decl) = *prev;
+ *prev = decl;
/* If appropriate, add decl to separate list of statics. We include
extern variables because they might turn out to be static later.
diff --git a/gcc/testsuite/g++.dg/modules/lambda-5_a.C
b/gcc/testsuite/g++.dg/modules/lambda-5_a.C
new file mode 100644
index 00000000000..6b54c8e3173
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/lambda-5_a.C
@@ -0,0 +1,23 @@
+// PR c++/105322
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr105322 }
+
+export module pr105322;
+
+struct A { };
+
+export
+inline void f1() {
+ A a;
+ auto g1 = [a] { }; // used to ICE here during stream out
+}
+
+export
+template<class...>
+void f2() {
+ A a;
+ auto g2 = [a] { };
+}
+
+export
+inline auto g3 = [a=A{}] { };
diff --git a/gcc/testsuite/g++.dg/modules/lambda-5_b.C
b/gcc/testsuite/g++.dg/modules/lambda-5_b.C
new file mode 100644
index 00000000000..e25a913b726
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/lambda-5_b.C
@@ -0,0 +1,10 @@
+// PR c++/105322
+// { dg-additional-options -fmodules-ts }
+
+import pr105322;
+
+int main() {
+ f1();
+ f2();
+ g3();
+}
--
2.42.0.398.ga9ecda2788
