c++: Fix two issues with auto function parameter [PR99806]

When we have a member function with auto parameter like this:

  struct S {
    void f(auto);
  };

cp_parser_member_declaration -> grokfield produces a FUNCTION_DECL
"void S::foo(auto:1)", and then finish_fully_implicit_template turns
that FUNCTION_DECL into a TEMPLATE_DECL.  The bug here is that we only
call cp_parser_save_default_args for a FUNCTION_DECL.  As a consequence,
abbrev10.C is rejected because we complain that the default argument has
not been defined, and abbrev11.C ICEs, because we don't re-parse the
delayed noexcept, so the DEFERRED_PARSE tree leaks into tsubst* where we
crash.  This patch fixes both issues.

gcc/cp/ChangeLog:

	PR c++/99806
	* parser.c (cp_parser_member_declaration): Call
	cp_parser_save_default_args even for function templates.  Use
	STRIP_TEMPLATE on the declaration we're passing.

gcc/testsuite/ChangeLog:

	PR c++/99806
	* g++.dg/concepts/abbrev10.C: New test.
	* g++.dg/concepts/abbrev11.C: New test.

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 59adac4..e6e6ed7 100644 (file)
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -26433,8 +26433,8 @@ cp_parser_member_declaration (cp_parser* parser)
                  || !DECL_DECLARES_FUNCTION_P (decl))
                finish_member_declaration (decl);
 
-             if (TREE_CODE (decl) == FUNCTION_DECL)
-               cp_parser_save_default_args (parser, decl);
+             if (DECL_DECLARES_FUNCTION_P (decl))
+               cp_parser_save_default_args (parser, STRIP_TEMPLATE (decl));
              else if (TREE_CODE (decl) == FIELD_DECL
                       && DECL_INITIAL (decl))
                /* Add DECL to the queue of NSDMI to be parsed later.  */

diff --git a/gcc/testsuite/g++.dg/concepts/abbrev10.C b/gcc/testsuite/g++.dg/concepts/abbrev10.C
new file mode 100644 (file)
index 0000000..b611346
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/abbrev10.C
@@ -0,0 +1,18 @@
+// PR c++/99806
+// { dg-do compile { target c++14 } }
+// { dg-additional-options "-fconcepts" }
+
+struct S {
+  void f(auto, auto, int = 3);
+  void f2(auto, auto, int = 3) { }
+  template<typename T> static T g(T, auto, int = 3);
+};
+
+void
+g ()
+{
+  S::g(1, 2);
+  S s;
+  s.f(1, 2);
+  s.f2(1, 2);
+}

diff --git a/gcc/testsuite/g++.dg/concepts/abbrev11.C b/gcc/testsuite/g++.dg/concepts/abbrev11.C
new file mode 100644 (file)
index 0000000..ddb4793
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/abbrev11.C
@@ -0,0 +1,10 @@
+// PR c++/99806
+// { dg-do compile { target c++14 } }
+// { dg-additional-options "-fconcepts" }
+
+template <typename T> concept C = requires (T a) { a.f(0); };
+struct S {
+  void f(auto) noexcept(B);
+  static constexpr bool B = true;
+};
+static_assert(C<S>, "");