[Concepts] Parsing of requires-clause in template-declaration
Summary:
This change implements parse-only acceptance of the optional
requires-clause in a template-declaration. Diagnostic testing is added
for cases where the grammar is ambiguous with the expectation that the
longest token sequence which matches the syntax of a
constraint-expression is consumed without backtracking.
Reviewers: faisalv, fraggamuffin, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D10462
llvm-svn: 240611
diff --git a/clang/test/Parser/cxx-concepts-ambig-constraint-expr.cpp b/clang/test/Parser/cxx-concepts-ambig-constraint-expr.cpp
new file mode 100644
index 0000000..12ab338
--- /dev/null
+++ b/clang/test/Parser/cxx-concepts-ambig-constraint-expr.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -std=c++14 -fconcepts-ts -x c++ %s -verify
+
+// Test parsing of constraint-expressions in cases where the grammar is
+// ambiguous with the expectation that the longest token sequence which matches
+// the syntax is consumed without backtracking.
+
+// type-specifier-seq in conversion-type-id
+template <typename T> requires (bool)&T::operator short
+unsigned int foo(); // expected-error {{C++ requires a type specifier for all declarations}}
+
+// type-specifier-seq in new-type-id
+template <typename T> requires (bool)sizeof new (T::f()) short
+unsigned int bar(); // expected-error {{C++ requires a type specifier for all declarations}}
+
+template<typename T> requires (bool)sizeof new (T::f()) unsigned // expected-error {{'struct' cannot be signed or unsigned}}
+struct X { }; // expected-error {{'X' cannot be defined in a type specifier}}
+
+// C-style cast
+// of function call on function-style cast
+template <typename T> requires (bool(T()))
+T (*fp)(); // expected-error {{use of undeclared identifier 'fp'}}
+
+// function-style cast
+// as the callee in a function call
+struct A {
+ static int t;
+ template <typename T> requires bool(T())
+ (A(T (&t))) { } // expected-error {{called object type 'bool' is not a function or function pointer}}
+};