From 64c0645bcb59546bebd51436d37ec48a7defd571 Mon Sep 17 00:00:00 2001
From: Joe Conigliaro <joe@vlang.io>
Date: Mon, 28 Dec 2020 20:09:43 +1100
Subject: [PATCH] checker: error when trying to propagate optional call in
 return stmt with ?

---
 vlib/v/checker/checker.v | 8 ++++++++
 vlib/v/gen/cgen.v        | 9 +++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 67b204070a..95051a003c 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2028,6 +2028,14 @@ pub fn (mut c Checker) return_stmt(mut return_stmt ast.Return) {
 				pos)
 		}
 	}
+	if exp_is_optional && return_stmt.exprs.len > 0 {
+		expr0 := return_stmt.exprs[0]
+		if expr0 is ast.CallExpr {
+			if expr0.or_block.kind == .propagate {
+				c.error('`?` is not needed, use `return ${expr0.name}()`', expr0.pos)
+			}
+		}
+	}
 }
 
 pub fn (mut c Checker) const_decl(mut node ast.ConstDecl) {
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index d972f2d66f..4ae1da4196 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -4101,7 +4101,7 @@ fn (mut g Gen) return_statement(node ast.Return) {
 		}
 	}
 	// regular cases
-	if fn_return_is_multi { // not_optional_none { //&& !fn_return_is_optional {
+	if fn_return_is_multi && node.exprs.len > 0 && !g.expr_is_multi_return_call(node.exprs[0]) { // not_optional_none { //&& !fn_return_is_optional {
 		// typ_sym := g.table.get_type_symbol(g.fn_decl.return_type)
 		// mr_info := typ_sym.info as table.MultiReturn
 		mut styp := ''
@@ -4182,7 +4182,12 @@ fn (mut g Gen) return_statement(node ast.Return) {
 		// normal return
 		return_sym := g.table.get_type_symbol(node.types[0])
 		// `return opt_ok(expr)` for functions that expect an optional
-		if fn_return_is_optional && !node.types[0].has_flag(.optional) && return_sym.name != 'Option' {
+		mut expr_type_is_opt := node.types[0].has_flag(.optional)
+		expr0 := node.exprs[0]
+		if expr0 is ast.CallExpr {
+			expr_type_is_opt = expr0.return_type.has_flag(.optional)
+		}
+		if fn_return_is_optional && !expr_type_is_opt && return_sym.name != 'Option' {
 			styp := g.base_type(g.fn_decl.return_type)
 			opt_type := g.typ(g.fn_decl.return_type)
 			// Create a tmp for this option