re PR c++/92439 ([concepts] trunk crashes on constraint satisfaction failure)

2019-11-27  Andrew Sutton  <asutton@lock3software.com>

	PR c++/92439
	Improve quality of diagnostics for subexpressions that need parens.

gcc/cp/
	* parser.c (cp_parser_requires_clause_opt): Add a flag to indicate
	when parsing a requires-clause before lambda parameters, and...
	(cp_parser_lambda_declarator_opt): ... use that here ...
	(cp_parser_type_parameter): ... and here ...
	(cp_parser_late_return_type_opt): ... and here ...
	(cp_parser_explicit_template_declaration): ... and here.
	(cp_parser_diagnose_ungrouped_constraint_plain): Adjust the message
	because this can apply to subexpressions that are not immediately
	after a requires-clause.
	(cp_parser_diagnose_ungrouped_constraint_rich): Likewise.
	(primary_constraint_error): New.
	(cp_parser_constraint_requires_parens): New.
	(cp_parser_unary_constraint_requires_parens): New.
	(cp_parser_constraint_primary_expression): Check for unary expressions
	before parsing the primary expression. Also check for binary and
	postfix operators after a successful parse of the primary expression.
	Force a re-parse if the result would form a lower-precedence string.
	(cp_parser_constraint_logical_and_expression): Propagate lambda flag;
	move checks for ill-formed constraints into the constraint primary
	expression.
	(cp_parser_constraint_logical_or_expression): Likewise.
	(cp_parser_requires_clause_expression): Propagate lambda flag.

gcc/testsuite/
	* g++.dg/cpp2a/concepts-requires20.C: New.

From-SVN: r278774

2 files changed, 71 insertions, 1 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8605b0b..9b22c91 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,4 +1,9 @@
-2019-11-18  Andrew Sutton  <asutton@lock3software.com>
+2019-11-27  Andrew Sutton  <asutton@lock3software.com>
+
+	PR c++/92439
+	* g++.dg/cpp2a/concepts-requires20.C: New.
+
+2019-11-27  Andrew Sutton  <asutton@lock3software.com>
 
 	PR c++/88395
 	* g++.dg/cpp2a/concepts-pr88395.C: New.
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-requires20.C b/gcc/testsuite/g++.dg/cpp2a/concepts-requires20.C
new file mode 100644
index 0000000..089db2b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-requires20.C
@@ -0,0 +1,65 @@
+// { dg-do compile { target c++2a } }
+
+template<typename ...>
+constexpr bool r () { return true; }
+
+template<typename ... Ts>
+  requires r<Ts...>() // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires ++N // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N++ // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N == 0 // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N ? true : false // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N = 0 // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N + 1 // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N - 1 // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N.x // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N->x && true // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N && N
+void f() { }
+
+template<typename T, T N>
+  requires N || N
+void f() { }
+
+template<typename T, T N>
+  requires N || !N // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires N[0] // { dg-error "enclose" }
+void f() { }
+
+template<typename T, T N>
+  requires static_cast<bool>(N) // { dg-error "enclose" }
+void f() { }
+