From 367691d18ac74b1f2d52d002dfb097a70b7814a6 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Fri, 27 Sep 2019 17:28:27 -0400
Subject: probably finished named return values

---
 main.c   |  3 +--
 test.toc |  1 +
 types.c  | 35 ++++++++++++++++++++++++++---------
 3 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/main.c b/main.c
index bba3a36..eecc4de 100644
--- a/main.c
+++ b/main.c
@@ -1,8 +1,7 @@
 /* 
 TODO:
-named return values
 optional params
-named params
+named args
 evaluator (simplify compile time constant expressions)
 re-do cgen
  */
diff --git a/test.toc b/test.toc
index e93cfb4..9ecb5f9 100644
--- a/test.toc
+++ b/test.toc
@@ -1,4 +1,5 @@
 main @= fn() {
+	 foo @= fn() i64 { return 3; };
 	 test @= fn(x : i64, y : i32, z,w: i64) ret1 : i64, ret2 : i64 {
 	 	  ret1 = x;
 	 };
diff --git a/types.c b/types.c
index 7ca8cf6..9fcd5f1 100644
--- a/types.c
+++ b/types.c
@@ -1,7 +1,8 @@
 typedef struct {
 	Array in_decls;	/* array of declarations we are currently inside */
 	Block *block;
-	Type *ret_type;	/* the return type of the function we're currently parsing. NULL for none. */
+	bool can_ret;
+	Type ret_type; /* the return type of the function we're currently parsing. */
 } Typer;
 
 static bool types_stmt(Typer *tr, Statement *s);
@@ -308,8 +309,6 @@ static bool type_can_be_truthy(Type *t) {
 
 static bool types_expr(Typer *tr, Expression *e) {
 	if (e->flags & EXPR_FLAG_FOUND_TYPE) return true;
-	Type *prev_ret_type = tr->ret_type;
-	
 	Type *t = &e->type;
 	t->flags = 0;
 	t->kind = TYPE_UNKNOWN; /* default to unknown type (in the case of an error) */
@@ -317,12 +316,22 @@ static bool types_expr(Typer *tr, Expression *e) {
 	bool success = true;
 	switch (e->kind) {
 	case EXPR_FN: {
+		Type prev_ret_type = tr->ret_type;
+		bool prev_can_ret = tr->can_ret;
 		FnExpr *f = &e->fn;
 		if (!type_of_fn(tr, f, t)) {
 			success = false;
 			goto fn_ret;
 		}
-		tr->ret_type = t->fn.types.data;
+		bool has_named_ret_vals = e->fn.ret_decls.data != NULL;
+		if (has_named_ret_vals) {
+			/* set return type to void to not allow return values */
+			tr->ret_type.kind = TYPE_VOID;
+			tr->ret_type.flags = 0;
+		} else {
+			tr->ret_type = *(Type *)t->fn.types.data;
+		}
+		tr->can_ret = true;
 		arr_foreach(&f->params, Declaration, decl)
 			add_ident_decls(&f->body, decl);
 		arr_foreach(&f->ret_decls, Declaration, decl)
@@ -354,7 +363,7 @@ static bool types_expr(Typer *tr, Expression *e) {
 				success = false;
 				goto fn_ret;
 			}
-		} else if (ret_type->kind != TYPE_VOID) {
+		} else if (ret_type->kind != TYPE_VOID && !has_named_ret_vals) {
 			Array stmts = e->fn.body.stmts;
 			if (stmts.len) {
 				Statement *last_stmt = (Statement *)stmts.data + (stmts.len - 1);
@@ -376,6 +385,7 @@ static bool types_expr(Typer *tr, Expression *e) {
 		}
 		fn_ret:
 		tr->ret_type = prev_ret_type;
+		tr->can_ret = prev_can_ret;
 		if (!success) return false;
 	} break;
 	case EXPR_LITERAL_INT:
@@ -779,19 +789,25 @@ static bool types_stmt(Typer *tr, Statement *s) {
 			return false;
 		break;
 	case STMT_RET:
-		if (!tr->ret_type) {
+		if (!tr->can_ret) {
 			err_print(s->where, "return outside of a function.");
 			return false;
 		}
 		if (s->ret.flags & RET_FLAG_EXPR) {
-			if (tr->ret_type->kind == TYPE_VOID) {
-				err_print(s->where, "Return value in void function.");
+			if (tr->ret_type.kind == TYPE_VOID) {
+				err_print(s->where, "Return value in function which should not return a value.");
 				return false;
 			}
 			if (!types_expr(tr, &s->ret.expr))
 				return false;
+			if (!type_eq(&tr->ret_type, &s->ret.expr.type)) {
+				char *got = type_to_str(&s->ret.expr.type);
+				char *expected = type_to_str(&tr->ret_type);
+				err_print(s->where, "Returning type %s in function which returns %s.", got, expected);
+				return false;
+			}
 		} else {
-			if (tr->ret_type->kind != TYPE_VOID) {
+			if (tr->ret_type.kind != TYPE_VOID) {
 				err_print(s->where, "No return value in non-void function.");
 				return false;
 			}
@@ -803,6 +819,7 @@ static bool types_stmt(Typer *tr, Statement *s) {
 
 static void typer_create(Typer *tr) {
 	tr->block = NULL;
+	tr->can_ret = false;
 	arr_create(&tr->in_decls, sizeof(Declaration *));
 }
 
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