On 11/9/24 9:28 AM, Nathaniel Shead wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
OK.
Alternatively, after this I'll work on an update of my P1815 (TU-local
entities) patch series [1] which would also solve this ICE by erroring
early due to attempting to emit a TU-local entity. As discussed in
patch #1 I believe this is incorrect but also seems out of scope of this
particular modification. I still think this patch would be useful
however, if only for the clarification of the behaviour of streaming
lambdas without an extra mangling scope.
[1]: https://gcc.gnu.org/pipermail/gcc-patches/2024-October/665108.html
-- >8 --
If a lambda doesn't have an extra mangling scope despite being in class
scope (such as associated with a type alias, currently), we shouldn't
ICE; this behaviour is fine as long as we don't need to merge.
In the future such lambdas should be rejected as being TU-local, but for
now this at least clarifies the intended behaviour if this edge case
occurs again.
PR c++/116568
gcc/cp/ChangeLog:
* module.cc (trees_out::get_merge_kind): All lambdas without
extra mangling scope now marked MK_unique.
gcc/testsuite/ChangeLog:
* g++.dg/modules/lambda-8.h: New test.
* g++.dg/modules/lambda-8_a.H: New test.
* g++.dg/modules/lambda-8_b.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
gcc/cp/module.cc | 30 ++++++++++++++---------
gcc/testsuite/g++.dg/modules/lambda-8.h | 7 ++++++
gcc/testsuite/g++.dg/modules/lambda-8_a.H | 5 ++++
gcc/testsuite/g++.dg/modules/lambda-8_b.C | 5 ++++
4 files changed, 35 insertions(+), 12 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/modules/lambda-8.h
create mode 100644 gcc/testsuite/g++.dg/modules/lambda-8_a.H
create mode 100644 gcc/testsuite/g++.dg/modules/lambda-8_b.C
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 4eefb2d3584..877e442bc41 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -10737,18 +10737,24 @@ trees_out::get_merge_kind (tree decl, depset *dep)
g++.dg/modules/lambda-6_a.C. */
if (DECL_IMPLICIT_TYPEDEF_P (STRIP_TEMPLATE (decl))
&& LAMBDA_TYPE_P (TREE_TYPE (decl)))
- if (tree scope = LAMBDA_TYPE_EXTRA_SCOPE (TREE_TYPE (decl)))
- {
- /* Lambdas attached to fields are keyed to its class. */
- if (TREE_CODE (scope) == FIELD_DECL)
- scope = TYPE_NAME (DECL_CONTEXT (scope));
- if (DECL_LANG_SPECIFIC (scope)
- && DECL_MODULE_KEYED_DECLS_P (scope))
- {
- mk = MK_keyed;
- break;
- }
- }
+ {
+ if (tree scope = LAMBDA_TYPE_EXTRA_SCOPE (TREE_TYPE (decl)))
+ {
+ /* Lambdas attached to fields are keyed to its class. */
+ if (TREE_CODE (scope) == FIELD_DECL)
+ scope = TYPE_NAME (DECL_CONTEXT (scope));
+ if (DECL_LANG_SPECIFIC (scope)
+ && DECL_MODULE_KEYED_DECLS_P (scope))
+ {
+ mk = MK_keyed;
+ break;
+ }
+ }
+ /* Lambdas without extra mangling scope are unique to the TU,
+ and cannot be merged; make them unique. */
+ mk = MK_unique;
+ break;
+ }
if (TREE_CODE (decl) == TEMPLATE_DECL
&& DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P (decl))
diff --git a/gcc/testsuite/g++.dg/modules/lambda-8.h
b/gcc/testsuite/g++.dg/modules/lambda-8.h
new file mode 100644
index 00000000000..0c66f053b20
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/lambda-8.h
@@ -0,0 +1,7 @@
+template <typename> struct S {
+ template <typename> static constexpr auto x = []{};
+ template <typename> using t = decltype([]{});
+};
+
+inline auto x = S<int>::x<int>;
+using t = S<int>::t<int>;
diff --git a/gcc/testsuite/g++.dg/modules/lambda-8_a.H
b/gcc/testsuite/g++.dg/modules/lambda-8_a.H
new file mode 100644
index 00000000000..d20958ee140
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/lambda-8_a.H
@@ -0,0 +1,5 @@
+// PR c++/116568
+// { dg-additional-options "-fmodules-ts -std=c++20" }
+// { dg-module-cmi {} }
+
+#include "lambda-8.h"
diff --git a/gcc/testsuite/g++.dg/modules/lambda-8_b.C
b/gcc/testsuite/g++.dg/modules/lambda-8_b.C
new file mode 100644
index 00000000000..05ea4afd8c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/lambda-8_b.C
@@ -0,0 +1,5 @@
+// PR c++/116568
+// { dg-additional-options "-fmodules-ts -std=c++20" }
+
+#include "lambda-8.h"
+import "lambda-8_a.H";
