add type-specifiers to let, N_UNINIT for uninitialized values

1 files changed, 44 insertions, 29 deletions

diff --git a/main.c b/main.c
index 9fba001..ae19e7a 100644
--- a/main.c
+++ b/main.c
@@ -75,14 +75,50 @@ void parse_return(Lexer *l, Proc *p) {
 	ctrl(p, NULL);
 }
 
+Type parse_type(Lexer *l, Proc *proc) {
+	(void)proc;
+	Type t = { .lvl = T_BOT };
+	if (l->tok == TOK_DEREF) {
+		lex_next(l);
+		t.t = T_PTR;
+		t.next = new(&proc->arena, Type);
+		*t.next = parse_type(l, proc);
+		return t;
+	}
+	lex_expected(l, TM_IDENT);
+	if (l->tok == TOK_IDENT) {
+		if (str_eql(l->ident, S("i64"))) {
+			t.t = T_INT;
+		} else if (str_eql(l->ident, S("bool"))) {
+			t.t = T_BOOL;
+		} else {
+			lex_error(l, LE_ERROR, S("unknown type"));
+		}
+	}
+	lex_next(l);
+	return t;
+}
+
 void parse_let(Lexer *l, Proc *p) {
 recurse:
 	lex_expect(l, TM_IDENT);
 	Str name = l->ident;
 	LexSpan pos = l->pos;
-	lex_expect(l, TM_EQL);
 	lex_next(l);
-	Node *rhs = parse_expr(l, p);
+	Node *rhs = NULL;
+	Type t = { .t = T_NONE };
+	if (l->tok != TOK_EQL) {
+		t = parse_type(l, p);
+		if (l->tok != TOK_EQL) {
+			rhs = node_new(p, N_UNINIT, p->start);
+			rhs->type = t;
+		}
+	}
+	if (l->tok == TOK_EQL) {
+		lex_next(l);
+		rhs = parse_expr(l, p);
+		if (t.t != T_NONE) type_expected(&t, rhs, l);
+	}
 	NameBinding *b = scope_bind(&p->scope, name, rhs, pos, p);
 	if (b) {
 		lex_error_at(l, pos, LE_WARN, S("shadowing previous declaration"));
@@ -125,6 +161,11 @@ void parse_assign(Lexer *l, Proc *p) {
 					type_desc(&e->type, &p->arena),
 					type_desc(&b->node->type, &p->arena)));
 	}
+	if (e->op == N_UNINIT) {
+		lex_error_at(l, e->src_pos, LE_ERROR,
+				str_fmt(&p->arena, "assigning from uninitialized %S value",
+					type_desc(&e->type, &p->arena)));
+	}
 	scope_update(b, e, p);
 }
 
@@ -317,29 +358,6 @@ void parse_stmt(Lexer *l, Proc *p) {
 	}
 }
 
-Type parse_type(Lexer *l, Proc *proc) {
-	(void)proc;
-	Type t = { .lvl = T_BOT };
-	if (l->tok == TOK_DEREF) {
-		lex_next(l);
-		t.t = T_PTR;
-		t.next = new(&proc->arena, Type);
-		*t.next = parse_type(l, proc);
-		return t;
-	}
-	if (l->tok == TOK_IDENT) {
-		if (str_eql(l->ident, S("i64"))) {
-			t.t = T_INT;
-		} else if (str_eql(l->ident, S("bool"))) {
-			t.t = T_BOOL;
-		}
-	} else {
-		lex_error(l, LE_ERROR, S("unknown type"));
-	}
-	lex_next(l);
-	return t;
-}
-
 void parse_args_list(Lexer *l, Proc *proc) {
 	Node *start = proc->start;
 	int i = 0;
@@ -390,10 +408,7 @@ void proc_opt_fwd(Proc *p, Lexer *l, Node *n) {
 	switch (n->op) {
 	case N_START:
 		for (int i = 0; i < n->out.len; i++) {
-			if (!(NMASK(n->out.data[i]->op) & (NM_LIT | NM_PROJ))) {
-				proc_opt_fwd(p, l, n->out.data[i]);
-				break;
-			}
+			proc_opt_fwd(p, l, n->out.data[i]);
 		}
 		break;
 	case N_IF_ELSE: