[gcc/devel/ranger] c++: Fix ICE-on-invalid with lambda template [PR94507]

[Aldy Hernandez]

https://gcc.gnu.org/g:77d6dfc929832a542a25fc455b90f1a4bc83229c

commit 77d6dfc929832a542a25fc455b90f1a4bc83229c
Author: Marek Polacek <polacek@redhat.com>
Date:   Mon Apr 6 19:59:04 2020 -0400

    c++: Fix ICE-on-invalid with lambda template [PR94507]
    
    While reducing something else I noticed that we ICE on the following
    invalid code.  In tsubst_lambda_expr, tsubst_template_decl has already
    reported an error and returned the error_mark_node, so make sure we
    don't ICE on that.  I'm using a goto here because we still have to
    do finish_struct because it does popclass ().
    
            PR c++/94507 - ICE-on-invalid with lambda template.
            * pt.c (tsubst_lambda_expr): Cope when tsubst_template_decl or
            tsubst_function_decl returns error_mark_node.
    
            * g++.dg/cpp2a/lambda-generic7.C: New test.

Diff:
---
 gcc/cp/ChangeLog                             |  6 ++++++
 gcc/cp/pt.c                                  | 11 +++++++++++
 gcc/testsuite/ChangeLog                      |  5 +++++
 gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C | 10 ++++++++++
 4 files changed, 32 insertions(+)

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 7c5edc266d6..50f1857a3ec 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/94507 - ICE-on-invalid with lambda template.
+	* pt.c (tsubst_lambda_expr): Cope when tsubst_template_decl or
+	tsubst_function_decl returns error_mark_node.
+
 2020-04-08  Martin Liska  <mliska@suse.cz>
 
 	PR c++/94314
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 256a937eace..050a57b2e2e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18953,6 +18953,11 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       if (oldtmpl)
 	{
 	  tmpl = tsubst_template_decl (oldtmpl, args, complain, fntype);
+	  if (tmpl == error_mark_node)
+	    {
+	      r = error_mark_node;
+	      goto out;
+	    }
 	  fn = DECL_TEMPLATE_RESULT (tmpl);
 	  finish_member_declaration (tmpl);
 	}
@@ -18960,6 +18965,11 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	{
 	  tmpl = NULL_TREE;
 	  fn = tsubst_function_decl (oldfn, args, complain, fntype);
+	  if (fn == error_mark_node)
+	    {
+	      r = error_mark_node;
+	      goto out;
+	    }
 	  finish_member_declaration (fn);
 	}
 
@@ -19025,6 +19035,7 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       maybe_add_lambda_conv_op (type);
     }
 
+out:
   finish_struct (type, /*attr*/NULL_TREE);
 
   insert_pending_capture_proxies ();
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index db4f6392493..6ed51141ac2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/94507 - ICE-on-invalid with lambda template.
+	* g++.dg/cpp2a/lambda-generic7.C: New test.
+
 2020-04-08  Alexandre Oliva <oliva@adacore.com>
 
 	* gcc.target/arm/fp16-aapcs-3.c: Explicitly use the
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C b/gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C
new file mode 100644
index 00000000000..bedba683671
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C
@@ -0,0 +1,10 @@
+// PR c++/94507 - ICE-on-invalid with lambda template.
+// { dg-do compile { target c++2a } }
+
+struct S { };
+
+template<typename T, typename U>
+auto foo(T, U)
+{
+  [] <> () { foo (S{}, S{}); }; // { dg-error "expected" }
+}