Lambdas can refer to local externs from their enclosing scope. When
the lambda's generic but the containing function is not a temploid,
we'll never have tsubsted the declaring decl so won't have a local
specialization. But in that case we can just use the decl we
tsubsting directly -- it's not dependent.
PR c++/99030
gcc/cp
* pt.c (tsubst_copy) [VAR_DECL]: For a DECL_LOCAL_DECL_P T is the
answer if there's no local specialization.
gcc/testsuite/
* g++.dg/lookup/pr99030.C: New.
--
Nathan Sidwell
diff --git c/gcc/cp/pt.c w/gcc/cp/pt.c
index f73deb3aee3..d8574f649b2 100644
--- c/gcc/cp/pt.c
+++ w/gcc/cp/pt.c
@@ -16650,11 +16650,16 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
r = tsubst (t, args, complain, in_decl);
else if (DECL_LOCAL_DECL_P (t))
{
- /* Local specialization will have been created when we
- instantiated the DECL_EXPR_DECL. */
+ /* Local specialization will usually have been created when
+ we instantiated the DECL_EXPR_DECL. */
r = retrieve_local_specialization (t);
if (!r)
- r = error_mark_node;
+ {
+ /* We're in a generic lambda referencing a local extern
+ from an outer block-scope of a non-template. */
+ gcc_checking_assert (LAMBDA_FUNCTION_P (current_function_decl));
+ r = t;
+ }
}
else if (local_variable_p (t)
&& uses_template_parms (DECL_CONTEXT (t)))
diff --git c/gcc/testsuite/g++.dg/lookup/pr99030.C w/gcc/testsuite/g++.dg/lookup/pr99030.C
new file mode 100644
index 00000000000..080847ca11c
--- /dev/null
+++ w/gcc/testsuite/g++.dg/lookup/pr99030.C
@@ -0,0 +1,16 @@
+// PR 99030 ICE with generic lambda accessing local extern
+// { dg-do compile { target c++14 } }
+
+void foo ()
+{
+ extern int a;
+ [] (auto b) { a; } (1);
+}
+
+template<typename T> void bar ()
+{
+ extern T a;
+ [] (auto b) { a; } (1);
+}
+
+template void bar<int> ();
