fix(rivetc.parser+rivet/parser): check missing function return type

lib/rivet/src/parser/decls.ri

@@ -615,7 +615,11 @@ extend Parser {
         ret_t_pos := self.tok.pos;
         if self.accept(.Arrow2) {
             is_result := self.accept(.Bang);
-            if self.tok.kind != .Lbrace {
+            if self.tok.kind == .Lbrace {
+                if !is_result {
+                    report.error("expected return type declaration", self.prev_tok.pos);
+                }
+            } else {
                 ret_type = self.parse_type();
             }
             if is_result {

lib/rivet/tests/tokenizer.ri

@@ -23,16 +23,15 @@ func tokenize(text: string) -> []token.Token {
     return tokens;
 }
 
-test "tokenizer: simple `func main() -> { }`" {
-    tokens := tokenize("func main() -> { }");
-    @assert(tokens.len == 7);
+test "tokenizer: simple `func main() { }`" {
+    tokens := tokenize("func main() { }");
+    @assert(tokens.len == 6);
     @assert(tokens[0].kind == .KwFunc);
     @assert(tokens[1].kind == .Name and tokens[1].lit == "main");
     @assert(tokens[2].kind == .Lparen);
     @assert(tokens[3].kind == .Rparen);
-    @assert(tokens[4].kind == .Arrow2);
-    @assert(tokens[5].kind == .Lbrace);
-    @assert(tokens[6].kind == .Rbrace);
+    @assert(tokens[4].kind == .Lbrace);
+    @assert(tokens[5].kind == .Rbrace);
 }
 
 test "tokenizer: number constant input format" {
@@ -59,29 +58,27 @@ test "tokenizer: float conversion and reading" {
 }
 
 test "tokenizer: preprocessor" {
-    mut tokens := tokenize("#if true func main() -> { } #endif");
-    @assert(tokens.len == 7);
+    mut tokens := tokenize("#if true func main() { } #endif");
+    @assert(tokens.len == 6);
     @assert(tokens[0].kind == .KwFunc);
     @assert(tokens[1].kind == .Name and tokens[1].lit == "main");
     @assert(tokens[2].kind == .Lparen);
     @assert(tokens[3].kind == .Rparen);
-    @assert(tokens[4].kind == .Arrow2);
-    @assert(tokens[5].kind == .Lbrace);
-    @assert(tokens[6].kind == .Rbrace);
+    @assert(tokens[4].kind == .Lbrace);
+    @assert(tokens[5].kind == .Rbrace);
 
-    tokens = tokenize("#if false func main() -> { } #endif");
+    tokens = tokenize("#if false func main() { } #endif");
     @assert(tokens.len == 1); // EndOfFile
 
-    tokens = tokenize("#if !CUSTOM_FLAG func main() -> { } #endif");
-    @assert(tokens.len == 7);
+    tokens = tokenize("#if !CUSTOM_FLAG func main() { } #endif");
+    @assert(tokens.len == 6);
     @assert(tokens[0].kind == .KwFunc);
     @assert(tokens[1].kind == .Name and tokens[1].lit == "main");
     @assert(tokens[2].kind == .Lparen);
     @assert(tokens[3].kind == .Rparen);
-    @assert(tokens[4].kind == .Arrow2);
-    @assert(tokens[5].kind == .Lbrace);
-    @assert(tokens[6].kind == .Rbrace);
+    @assert(tokens[4].kind == .Lbrace);
+    @assert(tokens[5].kind == .Rbrace);
 
-    tokens = tokenize("#if CUSTOM_FLAG func main() -> { } #endif");
+    tokens = tokenize("#if CUSTOM_FLAG func main() { } #endif");
     @assert(tokens.len == 1); // EndOfFile
 }

rivetc/src/parser.py

@@ -515,7 +515,10 @@ def parse_func_decl(
         ret_typ = self.comp.void_t
         if self.accept(Kind.Arrow2):
             is_result = self.accept(Kind.Bang)
-            if self.tok.kind != Kind.Lbrace:
+            if self.tok.kind == Kind.Lbrace:
+                if not is_result:
+                    report.error("expected return type declaration", self.prev_tok.pos)
+            else:
                 ret_typ = self.parse_type()
             if is_result:
                 ret_typ = type.Result(ret_typ)

tests/b_invalid/duplicate_symbols.out

@@ -1,5 +1,5 @@
 tests/b_invalid/duplicate_symbols.ri:15:6: error: module `duplicate_symbols` has duplicate symbol `other`
-   15 | func other(a: int32) -> { // FAIL
+   15 | func other(a: int32) { // FAIL
       |      ^
 tests/b_invalid/duplicate_symbols.ri:20:8: error: module `duplicate_symbols` has duplicate symbol `Gota`
    20 | struct Gota { } // FAIL

tests/b_invalid/duplicate_symbols.ri

@@ -12,7 +12,7 @@ func other(a: int32) {
     a := 1;
 }
 
-func other(a: int32) -> { // FAIL
+func other(a: int32) { // FAIL
     a := 1;
 }
 

tests/b_invalid/expected_type.out

@@ -1,4 +1,4 @@
 tests/b_invalid/expected_type.ri:3:11: error: expected type, found function
-    3 | func x(a: my_fn) -> {}
+    3 | func x(a: my_fn) {}
       |           ^
 rivetc: error: could not compile module `expected_type`, aborting due to previous error

tests/b_invalid/expected_type.ri

@@ -1,5 +1,5 @@
-func my_fn() -> { }
+func my_fn() { }
 
-func x(a: my_fn) -> {}
+func x(a: my_fn) {}
 
-func main() -> { }
+func main() { }

tests/b_invalid/types.ri

@@ -13,4 +13,4 @@ struct St {
     f5: =;
 }
 
-func main() -> { }
+func main() { }