[pushed] c++: conversion with trailing return type [PR101051]

[Jason Merrill via Gcc-patches]

We've had a diagnostic for this, but since r10-6571 added an assert to
splice_late_return_type, we need to diagnose before we call it.

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

        PR c++/101051

gcc/cp/ChangeLog:

        * decl.cc (grokdeclarator): Reject conversion with trailing return
        sooner.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp0x/trailing15.C: New test.
---
 gcc/cp/decl.cc                          |  7 +++++--
 gcc/testsuite/g++.dg/cpp0x/trailing15.C | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/trailing15.C

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 0ff13e99595..c136dbbba1a 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12866,6 +12866,11 @@ grokdeclarator (const cp_declarator *declarator,
                            "type specifier", name);
                return error_mark_node;
              }
+           if (late_return_type && sfk == sfk_conversion)
+             {
+               error ("a conversion function cannot have a trailing return 
type");
+               return error_mark_node;
+             }
            type = splice_late_return_type (type, late_return_type);
            if (type == error_mark_node)
              return error_mark_node;
@@ -13030,8 +13035,6 @@ grokdeclarator (const cp_declarator *declarator,
                    maybe_warn_cpp0x (CPP0X_EXPLICIT_CONVERSION);
                    explicitp = 2;
                  }
-               if (late_return_type_p)
-                 error ("a conversion function cannot have a trailing return 
type");
              }
            else if (sfk == sfk_deduction_guide)
              {
diff --git a/gcc/testsuite/g++.dg/cpp0x/trailing15.C 
b/gcc/testsuite/g++.dg/cpp0x/trailing15.C
new file mode 100644
index 00000000000..3fa74d08e39
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/trailing15.C
@@ -0,0 +1,14 @@
+// PR c++/101051
+// { dg-do compile { target c++11 } }
+
+template <class T>
+class Foo
+{
+    constexpr operator T() -> T {} // { dg-error "trailing return" }
+};
+
+struct S {
+  operator int() const -> double; // { dg-error "trailing return" }
+};
+
+class A { operator auto*() -> int; }; // { dg-error "auto|trailing return" }

base-commit: 8e4339f5023286d25c7dfa40b4c88e63b780cfd7
-- 
2.27.0