fix(parse): allow (to omit) semicolon after _unnamed-declaration_ (#479)

Author: JohelEGP

regression-tests/pure2-bugfix-for-unbraced-function-expression.cpp2

@@ -0,0 +1,15 @@
+t: type = {
+  operator[]: (this, f) = { }
+}
+
+main: () -> int = {
+  (x := t()) { x[:() -> _ = 0]; }
+  (x := t()) { x[:() -> _ = 0;]; }
+
+  assert(!(:() = 0; is int));
+
+  return :i32 = 0;
+}
+
+x :== :i32 = 0;
+y: i32     = 0;

regression-tests/test-results/gcc-13/pure2-bugfix-for-unbraced-function-expression.cpp.execution

@@ -0,0 +1,61 @@
+
+#define CPP2_IMPORT_STD          Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+#line 1 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+class t;
+#line 2 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+#line 1 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+class t {
+#line 2 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  public: auto operator[](auto const& f) const& -> void;
+  public: t() = default;
+  public: t(t const&) = delete; /* No 'that' constructor, suppress copy */
+  public: auto operator=(t const&) -> void = delete;
+
+#line 3 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+};
+
+[[nodiscard]] auto main() -> int;
+
+#line 14 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+auto inline constexpr x = cpp2::i32{0};
+extern cpp2::i32 y;
+
+//=== Cpp2 function definitions =================================================
+
+#line 1 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+
+#line 2 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  auto t::operator[](auto const& f) const& -> void{}
+
+#line 5 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+[[nodiscard]] auto main() -> int{
+{
+auto const& x = t();
+#line 6 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  {CPP2_ASSERT_IN_BOUNDS(x, []() mutable -> auto { return 0;  }); }
+}
+{
+auto const& x = t();
+#line 7 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  {CPP2_ASSERT_IN_BOUNDS(x, []() mutable -> auto { return 0;  }); }
+}
+
+#line 9 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+  cpp2::Default.expects(!((cpp2::is<int>([]() mutable -> void { 0;  }))), "");
+
+  return cpp2::i32{0}; 
+}
+
+#line 15 "pure2-bugfix-for-unbraced-function-expression.cpp2"
+cpp2::i32 y {0}; 
+

regression-tests/test-results/gcc-13/pure2-bugfix-for-unbraced-function-expression.cpp.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-unbraced-function-expression.cpp2... ok (all Cpp2, passes safety checks)
+

regression-tests/test-results/pure2-bugfix-for-unbraced-function-expression.cpp

@@ -5507,6 +5507,7 @@ class parser
                 !decl->has_name()
                 && "ICE: declaration should have been unnamed"
             );
+
             if (auto obj = std::get_if<declaration_node::an_object>(&decl->type)) {
                 if ((*obj)->is_wildcard()) {
                     error("an unnamed object at expression scope currently cannot have a deduced type (the reason to create an unnamed object is typically to create a temporary of a named type)");
@@ -5531,24 +5532,30 @@ class parser
                     next();
                     return {};
                 }
-                if (
-                    peek(-1) && peek(-1)->type() != lexeme::RightBrace  // it is short function syntax
-                    && curr().type() != lexeme::LeftParen               // not imediatelly called
-                    && curr().type() != lexeme::RightParen              // not as a last argument to function
-                    && curr().type() != lexeme::Comma                   // not as first or in-the-middle, function argument
-                ) {
-                    // this is a fix for a short function syntax that should have double semicolon used
-                    // (check comment in expression_statement(bool semicolon_required))
-                    // We simulate double semicolon by moving back to single semicolon.
-                    next(-1);
-                }
             }
             else {
                 error("(temporary alpha limitation) an unnamed declaration at expression scope must be a function or an object");
                 next();
                 return {};
             }
 
+            if (
+                peek(-1) && peek(-1)->type() != lexeme::RightBrace  // it is not a braced function expression
+                && curr().type() != lexeme::LeftParen               // not imediatelly called
+                && curr().type() != lexeme::RightParen              // not as a last argument to function
+                && curr().type() != lexeme::Comma                   // not as first or in-the-middle, function argument
+                && curr().type() != lexeme::Greater                 // not as the last argument to template
+                && curr().type() != lexeme::RightBracket            // not as the last index argument
+                && curr() != "is"                                   // not as the argument to is
+                && curr() != "as"                                   // not as the argument to as
+                && curr() != "do"                                   // not as `for`'s `next`.
+            ) {
+                // this is a fix for a short function syntax that should have double semicolon used
+                // (check comment in expression_statement(bool semicolon_required))
+                // We simulate double semicolon by moving back to single semicolon.
+                next(-1);
+            }
+
             n->expr = std::move(decl);
             return n;
         }