checker: require explicit return none (#8060)

vlib/io/buffered_reader.v

@@ -113,4 +113,5 @@ pub fn (mut r BufferedReader) read_line() ?string {
 		line << r.buf[r.offset..i]
 		r.offset = i
 	}
+	return none
 }

vlib/io/readerwriter.v

@@ -36,9 +36,11 @@ struct Zzz_CoerceInterfaceTableGeneration {
 }
 
 fn (_ Zzz_CoerceInterfaceTableGeneration) write(buf []byte) ?int {
+	return none
 }
 
 fn (_ Zzz_CoerceInterfaceTableGeneration) read(mut buf []byte) ?int {
+	return none
 }
 
 fn zzz_reader_writer_coerce_compiler() {

vlib/net/tcp.v

@@ -89,6 +89,7 @@ pub fn (c TcpConn) read_ptr(buf_ptr byteptr, len int) ?int {
 	} else {
 		wrap_error(code) ?
 	}
+	return none
 }
 
 pub fn (c TcpConn) read(mut buf []byte) ?int {

vlib/v/checker/checker.v

@@ -5165,13 +5165,6 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 			node.stmts << ast.Return{
 				pos: node.pos
 			}
-		} else {
-			node.stmts << ast.Return{
-				pos: node.pos
-				exprs: [ast.Expr(ast.None{
-					pos: node.pos
-				})]
-			}
 		}
 	}
 	c.stmts(node.stmts)

vlib/v/checker/tests/unknown_generic_type.out

@@ -1,7 +1,7 @@
-vlib/v/checker/tests/unknown_generic_type.vv:5:13: error: unknown type `Foo`
+vlib/v/checker/tests/unknown_generic_type.vv:6:13: error: unknown type `Foo`
-    3 |
+    4 |
-    4 | fn main() {
+    5 | fn main() {
-    5 |     x := decode<Foo>('{"name": "test"}')?
+    6 |     x := decode<Foo>('{"name": "test"}')?
       |                ~~~~~
-    6 |     println(x)
+    7 |     println(x)
-    7 | }
+    8 | }

vlib/v/checker/tests/unknown_generic_type.vv

@@ -1,4 +1,5 @@
 fn decode<T>(raw_data string) ?T {
+	return none
 }
 
 fn main() {

vlib/v/pkgconfig/pkgconfig.v

@@ -177,6 +177,7 @@ pub fn (mut pc PkgConfig) extend(pcdep &PkgConfig) ?string {
 			pc.libs_private << lib
 		}
 	}
+	return none
 }
 
 fn (mut pc PkgConfig) load_requires() {

vlib/v/tests/option_test.v

@@ -327,6 +327,7 @@ fn get_string(param bool) ?string {
 	if param {
 		return 'Hello World'
 	}
+	return none
 }
 
 fn test_option_auto_add_return_none() {

vlib/x/websocket/io.v

@@ -24,6 +24,7 @@ fn (mut ws Client) socket_read(mut buffer []byte) ?int {
 			}
 		}
 	}
+	return none
 }
 
 // socket_read reads from socket into the provided byte pointer and length
@@ -47,6 +48,7 @@ fn (mut ws Client) socket_read_ptr(buf_ptr byteptr, len int) ?int {
 			}
 		}
 	}
+	return none
 }
 
 // socket_write writes the provided byte array to the socket

vlib/x/websocket/message.v

@@ -177,6 +177,7 @@ pub fn (mut ws Client) read_next_message() ?Message {
 		}
 		return msg
 	}
+	return none
 }
 
 // payload_from_fragments returs the whole paylaod from fragmented message