re PR c++/77585 (g++ incorrectly decides that member function is called without…

re PR c++/77585 (g++ incorrectly decides that member function is called without object in generic lambda)

	PR c++/77585
	* pt.c (instantiate_decl): Push to class scope lambda resides
	within when instantiating a generic lambda function.

	PR c++/77585
	* g++.dg/cpp1y/pr77585.C: New.

From-SVN: r243723

gcc/cp/ChangeLog

+2016-12-15  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/77585
+	* pt.c (instantiate_decl): Push to class scope lambda resides
+	within when instantiating a generic lambda function.
+
 2016-12-14  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/78774

gcc/cp/pt.c

@@ -22484,6 +22484,7 @@ instantiate_decl (tree d, int defer_ok,
       tree tmpl_parm;
       tree spec_parm;
       tree block = NULL_TREE;
+      tree lambda_ctx = NULL_TREE;
 
       /* Save away the current list, in case we are instantiating one
 	 template from within the body of another.  */
@@ -22497,7 +22498,23 @@ instantiate_decl (tree d, int defer_ok,
 	  && TREE_CODE (DECL_CONTEXT (code_pattern)) == FUNCTION_DECL)
 	block = push_stmt_list ();
       else
+	{
+	  if (LAMBDA_FUNCTION_P (d))
+	    {
+	      /* When instantiating a lambda's templated function
+		 operator, we need to push the non-lambda class scope
+		 of the lambda itself so that the nested function
+		 stack is sufficiently correct to deal with this
+		 capture.  */
+	      lambda_ctx = DECL_CONTEXT (d);
+	      do 
+		lambda_ctx = decl_type_context (TYPE_NAME (lambda_ctx));
+	      while (lambda_ctx && LAMBDA_TYPE_P (lambda_ctx));
+	      if (lambda_ctx)
+		push_nested_class (lambda_ctx);
+	    }
 	  start_preparsed_function (d, NULL_TREE, SF_PRE_PARSED);
+	}
 
       /* Some typedefs referenced from within the template code need to be
 	 access checked at template instantiation time, i.e now. These
@@ -22565,6 +22582,8 @@ instantiate_decl (tree d, int defer_ok,
 	  d = finish_function (0);
 	  expand_or_defer_fn (d);
 	}
+      if (lambda_ctx)
+	pop_nested_class ();
 
       if (DECL_OMP_DECLARE_REDUCTION_P (code_pattern))
 	cp_check_omp_declare_reduction (d);

gcc/testsuite/ChangeLog

+2016-12-15  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/77585
+	* g++.dg/cpp1y/pr77585.C: New.
+
 2016-12-15  David Edelsohn  <dje.gcc@gmail.com>
 
 	* gcc.dg/tree-ssa/ssa-fre-55.c: Add -Wno-psabi.

gcc/testsuite/g++.dg/cpp1y/pr77585.C

+// PR c++/77585
+// { dg-do run { target c++14 } }
+
+// Confusion about this capture when instantiating generic lambda's
+// function operator
+
+template <typename F> int Eat (F &&f) { return f (1); }
+
+struct Foo {
+  int x = 1;
+  int Share () { return x++; }
+  int Frob (int);
+};
+
+int Foo::Frob (int r)
+{
+  auto lam = [&](auto) { return Share (); };
+  r += Eat (lam);
+
+  auto lam0 = [&](auto) {
+    auto lam1 = [&](auto) { return Share (); };
+    return Eat (lam1); };
+  r += Eat (lam0);
+
+  return r;
+}
+
+int Frob (int r) 
+{
+  auto lam = [&](auto) { return 1; };
+  r += Eat (lam);
+  return r;
+}
+
+
+int main ()
+{
+  Foo f;
+  
+  return Frob (f.Frob (0)) == 4 ? 0 : 1;
+}