From: Jason Merrill <jason@redhat.com>
Date: Thu, 7 Apr 2022 02:20:49 +0000 (-0400)
Subject: c++: nested generic lambda in DMI [PR101717]
X-Git-Tag: releases/gcc-10.4.0~150
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=20dc7a2119cc0a4e5ddc4a6899a7350621f05440;p=thirdparty%2Fgcc.git

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

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.

	PR c++/101717

gcc/cp/ChangeLog:

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

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1y/lambda-generic-this4.C: New test.
---

diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index f143cec61d3e..1b0cd869fe3c 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -743,6 +743,7 @@ 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,
@@ -761,6 +762,11 @@ 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));
 
@@ -770,7 +776,7 @@ 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 000000000000..38d582bec5e9
--- /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); };
+};