My fix for 94147 was confusing no-linkage with internal linkage, at the
language level. That's wrong. (the std is confusing here, because it
describes linkage of names (which is wrong), and lambdas have no names)
Lambdas with extra-scope, have linkage. However, at the
implementation-level that linkage is at least as restricted as the
linkage of the extra-scope decl.
Further, when instantiating a variable initialized by a lambda, we must
determine the visibility of the variable itself, before instantiating
its initializer. If the template arguments are internal (or
no-linkage), the variable will have internal linkage, regardless of the
linkage of the template it is instantiated from. We need to know that
before instantiating the lambda, so we can restrict its linkage correctly.
I'll commit this in a few days.
nathan
--
Nathan Sidwell
2020-04-10 Nathan Sidwell <nat...@acm.org>
PR c++/94426 = lambdas with internal linkage are different to no-linkage
* decl2.c (determine_visibility): A lambda's visibility is
affected by its extra scope.
* pt.c (instantiate_decl): Determine var's visibility before
instantiating its initializer.
* tree.c (no_linkage_check): Revert code looking at visibility of
lambda's extra scope.
gcc/cp/
* g++.dg/cpp0x/lambda/pr94426-[12].C: New.
* g++.dg/abi/lambda-vis.C: Drop a warning.
* g++.dg/cpp0x/lambda/lambda-mangle.C: Lambda visibility on
variable changes.
* g++.dg/opt/dump1.C: Drop warnings of no import.
diff --git c/gcc/cp/decl2.c w/gcc/cp/decl2.c
index 6cf72b432e2..293df990435 100644
--- c/gcc/cp/decl2.c
+++ w/gcc/cp/decl2.c
@@ -2527,6 +2527,21 @@ determine_visibility (tree decl)
else if (DECL_LANG_SPECIFIC (decl) && DECL_USE_TEMPLATE (decl))
template_decl = decl;
+ if (TREE_CODE (decl) == TYPE_DECL
+ && LAMBDA_TYPE_P (TREE_TYPE (decl))
+ && CLASSTYPE_LAMBDA_EXPR (TREE_TYPE (decl)) != error_mark_node)
+ if (tree extra = LAMBDA_TYPE_EXTRA_SCOPE (TREE_TYPE (decl)))
+ {
+ /* The lambda's visibility is limited by that of its extra
+ scope. */
+ int vis = 0;
+ if (TYPE_P (extra))
+ vis = type_visibility (extra);
+ else
+ vis = expr_visibility (extra);
+ constrain_visibility (decl, vis, false);
+ }
+
/* If DECL is a member of a class, visibility specifiers on the
class can influence the visibility of the DECL. */
tree class_type = NULL_TREE;
diff --git c/gcc/cp/pt.c w/gcc/cp/pt.c
index 050a57b2e2e..0a8ec3198d2 100644
--- c/gcc/cp/pt.c
+++ w/gcc/cp/pt.c
@@ -25541,6 +25541,14 @@ instantiate_decl (tree d, bool defer_ok, bool expl_inst_class_mem_p)
c_inhibit_evaluation_warnings = 0;
}
+ if (VAR_P (d))
+ {
+ /* The variable might be a lambda's extra scope, and that
+ lambda's visibility depends on D's. */
+ maybe_commonize_var (d);
+ determine_visibility (d);
+ }
+
/* Mark D as instantiated so that recursive calls to
instantiate_decl do not try to instantiate it again. */
DECL_TEMPLATE_INSTANTIATED (d) = 1;
diff --git c/gcc/cp/tree.c w/gcc/cp/tree.c
index d1192b7e094..1d311b0fe61 100644
--- c/gcc/cp/tree.c
+++ w/gcc/cp/tree.c
@@ -2780,9 +2780,10 @@ verify_stmt_tree (tree t)
cp_walk_tree (&t, verify_stmt_tree_r, &statements, NULL);
}
-/* Check if the type T depends on a type with no linkage and if so, return
- it. If RELAXED_P then do not consider a class type declared within
- a vague-linkage function to have no linkage. */
+/* Check if the type T depends on a type with no linkage and if so,
+ return it. If RELAXED_P then do not consider a class type declared
+ within a vague-linkage function to have no linkage. Remember:
+ no-linkage is not the same as internal-linkage*/
tree
no_linkage_check (tree t, bool relaxed_p)
@@ -2801,17 +2802,6 @@ no_linkage_check (tree t, bool relaxed_p)
tree extra = LAMBDA_TYPE_EXTRA_SCOPE (t);
if (!extra)
return t;
-
- /* If the mangling scope is internal-linkage or not repeatable
- elsewhere, the lambda effectively has no linkage. (Sadly
- we're not very careful with the linkages of types.) */
- if (TREE_CODE (extra) == VAR_DECL
- && !(TREE_PUBLIC (extra)
- && (processing_template_decl
- || (DECL_LANG_SPECIFIC (extra) && DECL_USE_TEMPLATE (extra))
- /* DECL_COMDAT is set too late for us to check. */
- || DECL_VAR_DECLARED_INLINE_P (extra))))
- return t;
}
/* Otherwise there's no point in checking linkage on template functions; we
diff --git c/gcc/testsuite/g++.dg/abi/lambda-vis.C w/gcc/testsuite/g++.dg/abi/lambda-vis.C
index 89683b2076a..c1033f501a3 100644
--- c/gcc/testsuite/g++.dg/abi/lambda-vis.C
+++ w/gcc/testsuite/g++.dg/abi/lambda-vis.C
@@ -2,7 +2,7 @@
// { dg-options "-fno-inline" }
template<typename T> int sfoo (T); // { dg-warning "used but never defined" }
-template<typename T> int gfoo (T); // { dg-warning "used but never defined" }
+template<typename T> int gfoo (T); // OK, but not completable
template<typename T> int ifoo (T); // OK
template<typename T> struct Wrapper {};
template<typename T> Wrapper<T> capture (T &&) {return Wrapper<T> ();}
diff --git c/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle.C w/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle.C
index 7894ef3051e..ef4bad8698b 100644
--- c/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle.C
+++ w/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle.C
@@ -54,9 +54,12 @@ void bar()
[]{}();
}
-// lambdas used in non-template, non-class body initializers are internal.
+// lambdas used in namespace-scope initializers have the linkage of
+// the decl
// { dg-final { scan-assembler-not "weak\[^\n\r\]*_ZNKUlv" } }
-// { dg-final { scan-assembler-not "weak\[^\n\r\]*variable" } }
+// { dg-final { scan-assembler "weak\[^\n\r\]*variableMUlvE_clEv" { target c++14_down } } }
+// in c++17 and up, this operator() become constexpr, no not emitted
+// { dg-final { scan-assembler-not "weak\[^\n\r\]*variableMUlvE_clEv" { target c++17 } } }
int variable = []{return 1;}();
// And a template instantiated with such a lambda is also internal.
diff --git c/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-1.C w/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-1.C
new file mode 100644
index 00000000000..ae7cbf03091
--- /dev/null
+++ w/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-1.C
@@ -0,0 +1,17 @@
+// { dg-do compile { target c++14 } }
+// PR 94426 ICE mangling lambda
+// { dg-options {-flto -O2} }
+
+template <bool> using Void = void;
+
+template <typename U> bool Init (U) {return true;}
+template <typename> bool VAR = Init ([] {});
+
+template <typename T>
+Void<false && VAR<T>> Foo (T)
+{}
+
+void q ()
+{
+ Foo ([] {});
+}
diff --git c/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-2.C w/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-2.C
new file mode 100644
index 00000000000..3db864c604b
--- /dev/null
+++ w/gcc/testsuite/g++.dg/cpp0x/lambda/pr94426-2.C
@@ -0,0 +1,20 @@
+// { dg-do compile { target c++14 } }
+// PR 94426 ICE mangling lambda
+
+template <bool> using Void = void;
+
+template <typename U> bool Init (U) {return true;}
+template <typename> bool VAR = Init ([] {});
+
+template <typename T>
+Void<false && VAR<T>> Foo (T)
+{}
+
+void q ()
+{
+ Foo ([] {});
+}
+
+// The instantiation of VAR becomes local
+// { dg-final { scan-assembler {.local _Z3VARIZ1qvEUlvE_E} { target { i?86-*-* x86_64-*-* } } } }
+// { dg-final { scan-assembler {.comm _Z3VARIZ1qvEUlvE_E,1,1} { target { i?86-*-* x86_64-*-* } } } }
diff --git c/gcc/testsuite/g++.dg/opt/dump1.C w/gcc/testsuite/g++.dg/opt/dump1.C
index f813044456c..38ed055d5c6 100644
--- c/gcc/testsuite/g++.dg/opt/dump1.C
+++ w/gcc/testsuite/g++.dg/opt/dump1.C
@@ -312,7 +312,7 @@ namespace std __attribute__ ((__visibility__ ("default")))
typename __add_ref<
typename tuple_element<__i, tuple<_Elements...>>::type
>::type
- get(tuple<_Elements...>& __t) noexcept; // { dg-warning "used but never defined" }
+ get(tuple<_Elements...>& __t) noexcept;
template<std::size_t... _Indexes>
struct _Index_tuple
{};
@@ -387,7 +387,7 @@ namespace std __attribute__ ((__visibility__ ("default")))
};
template<typename _Callable, typename... _Args>
typename _Bind_simple_helper<_Callable, _Args...>::__type
- __bind_simple(_Callable&& __callable, _Args&&... __args) // { dg-warning "used but never defined" }
+ __bind_simple(_Callable&& __callable, _Args&&... __args)
;
union _Any_data
;
@@ -404,7 +404,7 @@ namespace std __attribute__ ((__visibility__ ("default")))
{
protected:
static _Functor*
- _M_get_pointer(const _Any_data& __source) // { dg-warning "used but never defined" }
+ _M_get_pointer(const _Any_data& __source)
;
};
};
@@ -511,7 +511,7 @@ namespace std __attribute__ ((__visibility__ ("default")))
_S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
{ ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); }
static pointer
- allocate(_Alloc& __a, size_type __n) // { dg-warning "used but never defined" }
+ allocate(_Alloc& __a, size_type __n)
;
template<typename _Tp, typename... _Args>
static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
