The standard says that in a generic lambda we should speculatively capture
'this' if we see a call to an overload set that contains a non-static member
function, but it seems wrong to reject the program if we can't capture,
since it might not actually be needed.
Tested x86_64-pc-linux-gnu, applying to trunk.
* lambda.c (lambda_expr_this_capture): Change add_capture_p to int.
(maybe_generic_this_capture): Pass -1.
---
gcc/cp/cp-tree.h | 2 +-
gcc/cp/lambda.c | 9 +++++----
gcc/testsuite/g++.dg/cpp1y/lambda-generic-this3.C | 13 +++++++++++++
gcc/cp/ChangeLog | 4 ++++
4 files changed, 23 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/lambda-generic-this3.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 879712f6dbc..91bc82b85e5 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7151,7 +7151,7 @@ extern bool is_capture_proxy (tree);
extern bool is_normal_capture_proxy (tree);
extern bool is_constant_capture_proxy (tree);
extern void register_capture_members (tree);
-extern tree lambda_expr_this_capture (tree, bool);
+extern tree lambda_expr_this_capture (tree, int);
extern void maybe_generic_this_capture (tree, tree);
extern tree maybe_resolve_dummy (tree, bool);
extern tree current_nonlambda_function (void);
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 7032168fb7b..d178f15a4da 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -730,10 +730,11 @@ add_default_capture (tree lambda_stack, tree id, tree
initializer)
/* Return the capture pertaining to a use of 'this' in LAMBDA, in the
form of an INDIRECT_REF, possibly adding it through default
- capturing, if ADD_CAPTURE_P is true. */
+ capturing, if ADD_CAPTURE_P is nonzero. If ADD_CAPTURE_P is negative,
+ try to capture but don't complain if we can't. */
tree
-lambda_expr_this_capture (tree lambda, bool add_capture_p)
+lambda_expr_this_capture (tree lambda, int add_capture_p)
{
tree result;
@@ -829,7 +830,7 @@ lambda_expr_this_capture (tree lambda, bool add_capture_p)
result = this_capture;
else if (!this_capture)
{
- if (add_capture_p)
+ if (add_capture_p == 1)
{
error ("%<this%> was not captured for this lambda function");
result = error_mark_node;
@@ -934,7 +935,7 @@ maybe_generic_this_capture (tree object, tree fns)
&& DECL_NONSTATIC_MEMBER_FUNCTION_P (*iter))
{
/* Found a non-static member. Capture this. */
- lambda_expr_this_capture (lam, true);
+ lambda_expr_this_capture (lam, /*maybe*/-1);
break;
}
}
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this3.C
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this3.C
new file mode 100644
index 00000000000..2bd287cc368
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this3.C
@@ -0,0 +1,13 @@
+// PR c++/87685
+// { dg-do compile { target c++14 } }
+
+struct A
+{
+ template <typename T> static void f(T) {}
+ void f() {}
+
+ void foo()
+ {
+ [] (auto&& v) { A::f(v); }; // OK if parameter type is specified
+ }
+};
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a41044683fe..e7780e7eb12 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,9 @@
2019-02-21 Jason Merrill <[email protected]>
+ PR c++/87685 - generic lambda 'this' capture error.
+ * lambda.c (lambda_expr_this_capture): Change add_capture_p to int.
+ (maybe_generic_this_capture): Pass -1.
+
PR c++/88394 - ICE with VLA init-capture.
* lambda.c (is_normal_capture_proxy): Check DECL_CAPTURED_VARIABLE.
base-commit: a7ea8f9672905a517f73ea2764a4301ddc8e3184
--
2.20.1
