On 4/8/20 9:44 AM, Marek Polacek wrote:
On Wed, Apr 08, 2020 at 08:55:08AM -0400, Jason Merrill via Gcc-patches wrote:
On 4/6/20 9:05 PM, Marek Polacek wrote:
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 ().

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

        PR c++/94507 - ICE-on-invalid with lambda template.
        * pt.c (tsubst_lambda_expr): Cope when tsubst_template_decl returns
        error_mark_node.

OK.

        * g++.dg/cpp2a/lambda-generic7.C: New test.
---
   gcc/cp/pt.c                                  |  6 ++++++
   gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C | 10 ++++++++++
   2 files changed, 16 insertions(+)
   create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 6122227c22f..f804ba18692 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18876,6 +18876,11 @@ 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);
        }

Perhaps we also want an early exit if the tsubst_function_decl in the else
clause returns error_mark_node?

Can't hurt (but don't have a testcase for it).

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
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.
---
  gcc/cp/pt.c                                  | 11 +++++++++++
  gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C | 10 ++++++++++
  2 files changed, 21 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-generic7.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 6122227c22f..b9cbdb36de7 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18876,6 +18876,11 @@ 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);
        }
@@ -18883,6 +18888,11 @@ 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);
        }
@@ -18948,6 +18958,7 @@ 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/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" }
+}

base-commit: 130f703da0c0d7b785d394b17df884379b4aadd9


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