From f8fac476b5ce4b9a37ea2b257d9da810f8c507be Mon Sep 17 00:00:00 2001 From: Nathan Sidwell Date: Wed, 10 Feb 2021 05:29:39 -0800 Subject: [PATCH] c++: generic lambdas and local-externs from outer scopes [PR 99030] 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. --- gcc/cp/pt.c | 11 ++++++++--- gcc/testsuite/g++.dg/lookup/pr99030.C | 16 ++++++++++++++++ 2 files changed, 24 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/g++.dg/lookup/pr99030.C diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index f73deb3aee3..d8574f649b2 100644 --- a/gcc/cp/pt.c +++ b/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 a/gcc/testsuite/g++.dg/lookup/pr99030.C b/gcc/testsuite/g++.dg/lookup/pr99030.C new file mode 100644 index 00000000000..080847ca11c --- /dev/null +++ b/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 void bar () +{ + extern T a; + [] (auto b) { a; } (1); +} + +template void bar (); -- 2.30.2