[pushed] c++: nested generic lambda in DMI [PR101717]

[Jason Merrill via Gcc-patches]

We were already checking COMPLETE_TYPE_P to recognize instantiation of a
generic lambda, but didn't consider that we might be nested in a non-generic
lambda.

Tested x86_64-pc-linux-gnu, applying to trunk.

        PR c++/101717

gcc/cp/ChangeLog:

        * lambda.cc (lambda_expr_this_capture): Check all enclosing
        lambdas for completeness.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp1y/lambda-generic-this4.C: New test.
---
 gcc/cp/lambda.cc                                  | 8 +++++++-
 gcc/testsuite/g++.dg/cpp1y/lambda-generic-this4.C | 7 +++++++
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/lambda-generic-this4.C

diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc
index 4cc3a47f9c2..f22798d51e8 100644
--- a/gcc/cp/lambda.cc
+++ b/gcc/cp/lambda.cc
@@ -741,6 +741,7 @@ lambda_expr_this_capture (tree lambda, int add_capture_p)
     {
       tree lambda_stack = NULL_TREE;
       tree init = NULL_TREE;
+      bool saw_complete = false;
 
       /* If we are in a lambda function, we can move out until we hit:
            1. a non-lambda function or NSDMI,
@@ -759,6 +760,11 @@ lambda_expr_this_capture (tree lambda, int add_capture_p)
                                      lambda_stack);
 
          tree closure = LAMBDA_EXPR_CLOSURE (tlambda);
+         if (COMPLETE_TYPE_P (closure))
+           /* We're instantiating a generic lambda op(), the containing
+              scope may be gone.  */
+           saw_complete = true;
+
          tree containing_function
            = decl_function_context (TYPE_NAME (closure));
 
@@ -768,7 +774,7 @@ lambda_expr_this_capture (tree lambda, int add_capture_p)
              /* Lambda in an NSDMI.  We don't have a function to look up
                 'this' in, but we can find (or rebuild) the fake one from
                 inject_this_parameter.  */
-             if (!containing_function && !COMPLETE_TYPE_P (closure))
+             if (!containing_function && !saw_complete)
                /* If we're parsing a lambda in a non-local class,
                   we can find the fake 'this' in scope_chain.  */
                init = scope_chain->x_current_class_ptr;
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this4.C 
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this4.C
new file mode 100644
index 00000000000..38d582bec5e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this4.C
@@ -0,0 +1,7 @@
+// PR c++/101717
+// { dg-do compile { target c++14 } }
+
+struct x {
+  static void f() { }
+  void (*_)() = [] { [=](auto) { f(); }(0); };
+};

base-commit: d9421784980276b42ecdce85b6dde28e965c88c6
-- 
2.27.0