Remove confusion between function body and function with inline struct as return type

Signed-off-by: Mel <mel@rnrd.eu>

1 files changed, 10 insertions, 1 deletions

diff --git a/boot/parse.c b/boot/parse.c
index c06c5d3..9aeaf94 100644
--- a/boot/parse.c
+++ b/boot/parse.c
@@ -267,7 +267,16 @@ parser_function_header_node(struct Parser* p, struct Parser_Error* error)
     header.span = span_merge(open_parameters_token.span, close_parameters_token.span);
 
     struct Token next = parser_peek(p);
-    if (token_can_begin_type(&next)) {
+    struct Token further = parser_peek_further(p);
+    // NOTE: this is very uncomfortable. to avoid ambiguity between a no-return-type function body
+    // (i.e. `fun () {`) and a function with a return type of inline
+    // structure (i.e. `fun () {x int} {`), we require that inline structs are declared in one line,
+    // without a line-break, and function bodies always have a line-break after the opening brace.
+    // this means that we cannot have a single line function, and we can't have a function with an
+    // inline structure as a return type that is too long to fit on a single line.
+    // TODO: to allow single line functions, introduce a `:` token as a replacement for the
+    // opening brace. `fun (x int): x + 1`
+    if (token_can_begin_type(&next) && !token_is(&further, TOKEN_NEWLINE)) {
         header.return_type = CHECK_RETURN(parser_node_type(p, error), struct Function_Header_Node);
         header.span = span_merge(header.span, header.return_type->span);
     }