fix(parse)!: accept short constexpr function with requires (hsutter#922)

Author: JohelEGP

regression-tests/pure2-requires-clauses.cpp2

@@ -15,9 +15,12 @@ f:  <T: type, U: type>
     return a * b;
 }
 
+f: (x) -> int requires true == x;
+
 v: <T> const T requires std::same_as<T, i32> = 0;
 
 main: () = {
     _: X<int,int> = ();
-    std::cout << f<int,int>(2,5);
+    std::cout << f<int,int>(2,5)
+              << f(0);
 }

regression-tests/test-results/gcc-13/pure2-requires-clauses.cpp.execution

@@ -1 +1 @@
-10
+100

regression-tests/test-results/pure2-requires-clauses.cpp

@@ -38,10 +38,14 @@ CPP2_REQUIRES (std::is_same_v<T,int> && std::is_same_v<U,int> && std::is_same_v<
 ;
 
 #line 18 "pure2-requires-clauses.cpp2"
+[[nodiscard]] constexpr auto f(auto const& x) -> int
+CPP2_REQUIRES (true) ;
+
+#line 20 "pure2-requires-clauses.cpp2"
 template<typename T> 
 CPP2_REQUIRES_ (std::same_as<T,cpp2::i32>) extern T const v;
 
-#line 20 "pure2-requires-clauses.cpp2"
+#line 22 "pure2-requires-clauses.cpp2"
 auto main() -> int;
 
 //=== Cpp2 function definitions =================================================
@@ -61,12 +65,17 @@ requires (std::is_same_v<T,int> && std::is_same_v<U,int> && std::is_same_v<CPP2_
     return CPP2_FORWARD(a) * CPP2_FORWARD(b); 
 }
 
+[[nodiscard]] constexpr auto f(auto const& x) -> int
+requires (true)  { return x;  }
+
+#line 20 "pure2-requires-clauses.cpp2"
 template<typename T> 
 requires (std::same_as<T,cpp2::i32>) T const v {0}; 
 
-#line 20 "pure2-requires-clauses.cpp2"
+#line 22 "pure2-requires-clauses.cpp2"
 auto main() -> int{
-    X<int,int> auto_21_5 {}; 
-    std::cout << f<int,int>(2, 5);
+    X<int,int> auto_23_5 {}; 
+    std::cout << f<int,int>(2, 5) 
+              << f(0);
 }
 

source/parse.h

@@ -4962,7 +4962,7 @@ auto pretty_print_visualize(declaration_node const& n, int indent, bool include_
 
     auto metafunctions = std::string{};
     {
-    auto as_comment = 
+    auto as_comment =
         !n.metafunctions.empty()
         && !include_metafunctions_list;
     if (as_comment) {
@@ -8315,7 +8315,7 @@ class parser
 
                 n->requires_pos = curr().position();
                 next();
-                auto e = logical_or_expression();
+                auto e = logical_or_expression(true, false);
                 if (!e) {
                     error("'requires' must be followed by an expression");
                     return {};