all: improve unused variable warning (fix x = 1, x += 1 etc)

Author: medvednikov

thirdparty/sokol/sokol_app2.h

@@ -1,14 +1,14 @@
 
 @implementation MyView2
 
-int xx = 0;
+int __v_sokol_inited = 0;
 
 // Alternative drawRect which calls a frame function with native Cocoa calls
 - (void)drawRect:(NSRect)rect {
-	puts("drawRect()");
-	if (xx == 0) {
+	//puts("drawRect()");
+	if (__v_sokol_inited == 0) {
         _sapp_call_init();
-       xx = 1;
+       __v_sokol_inited = 1;
       }
     _sapp_call_frame_native();
 }

vlib/builtin/builtin.c.v

@@ -120,12 +120,11 @@ pub fn eprintln(s string) {
 				C.fprintf(C.stderr, c'%.*s\n', s.len, s.str)
 			}
 		} $else {
-			mut n := 0
 			if s.str == 0 {
-				n = C.write(2, c'eprintln(NIL)\n', 14)
+				_ = C.write(2, c'eprintln(NIL)\n', 14)
 			} else {
-				n = C.write(2, s.str, s.len)
-				n = C.write(2, c'\n', 1)
+				_ = C.write(2, s.str, s.len)
+				_ = C.write(2, c'\n', 1)
 			}
 		}
 		C.fflush(C.stderr)
@@ -158,11 +157,10 @@ pub fn eprint(s string) {
 				C.fprintf(C.stderr, c'%.*s', s.len, s.str)
 			}
 		} $else {
-			mut n := 0
 			if s.str == 0 {
-				n = C.write(2, c'eprint(NIL)', 11)
+				_ = C.write(2, c'eprint(NIL)', 11)
 			} else {
-				n = C.write(2, s.str, s.len)
+				_ = C.write(2, s.str, s.len)
 			}
 		}
 		C.fflush(C.stderr)
@@ -172,7 +170,6 @@ pub fn eprint(s string) {
 // print prints a message to stdout. Unlike `println` stdout is not automatically flushed.
 // A call to `flush()` will flush the output buffer to stdout.
 pub fn print(s string) {
-	mut n := 0
 	$if android {
 		C.fprintf(C.stdout, c'%.*s', s.len, s.str)
 	} $else $if ios {
@@ -181,7 +178,7 @@ pub fn print(s string) {
 	} $else $if freestanding {
 		bare_print(s.str, u64(s.len))
 	} $else {
-		n = C.write(1, s.str, s.len)
+		_ = C.write(1, s.str, s.len)
 	}
 }
 
@@ -194,7 +191,6 @@ fn C.asl_log(voidptr, voidptr, int, charptr)
 */
 // println prints a message with a line end, to stdout. stdout is flushed.
 pub fn println(s string) {
-	mut n := 0
 	if s.str == 0 {
 		$if android {
 			C.fprintf(C.stdout, c'println(NIL)\n')
@@ -204,7 +200,7 @@ pub fn println(s string) {
 			bare_print(s.str, u64(s.len))
 			bare_print(c'println(NIL)\n', 13)
 		} $else {
-			n = C.write(1, c'println(NIL)\n', 13)
+			_ = C.write(1, c'println(NIL)\n', 13)
 		}
 		return
 	}
@@ -216,8 +212,8 @@ pub fn println(s string) {
 		bare_print(s.str, u64(s.len))
 		bare_print(c'\n', 1)
 	} $else {
-		n = C.write(1, s.str, s.len)
-		n = C.write(1, c'\n', 1)
+		_ = C.write(1, s.str, s.len)
+		_ = C.write(1, c'\n', 1)
 	}
 }
 

vlib/builtin/builtin_nix.c.v

@@ -145,5 +145,6 @@ fn break_if_debugger_attached() {
 	unsafe {
 		mut ptr := &voidptr(0)
 		*ptr = voidptr(0)
+		_ = ptr
 	}
 }

vlib/os/os_c.v

@@ -740,11 +740,10 @@ pub fn is_link(path string) bool {
 
 // chdir changes the current working directory to the new directory in `path`.
 pub fn chdir(path string) {
-	mut n := 0
 	$if windows {
 		C._wchdir(path.to_wide())
 	} $else {
-		n = C.chdir(&char(path.str))
+		_ = C.chdir(&char(path.str))
 	}
 }
 

vlib/os/process_nix.c.v

@@ -3,12 +3,11 @@ module os
 fn C.setpgid(pid int, pgid int) int
 
 fn (mut p Process) unix_spawn_process() int {
-	mut n := 0
 	mut pipeset := [6]int{}
 	if p.use_stdio_ctl {
-		n = C.pipe(&pipeset[0]) // pipe read end 0 <- 1 pipe write end
-		n = C.pipe(&pipeset[2]) // pipe read end 2 <- 3 pipe write end
-		n = C.pipe(&pipeset[4]) // pipe read end 4 <- 5 pipe write end
+		_ = C.pipe(&pipeset[0]) // pipe read end 0 <- 1 pipe write end
+		_ = C.pipe(&pipeset[2]) // pipe read end 2 <- 3 pipe write end
+		_ = C.pipe(&pipeset[4]) // pipe read end 4 <- 5 pipe write end
 	}
 	pid := fork()
 	if pid != 0 {

vlib/v/cflag/cflags.v

@@ -33,10 +33,10 @@ pub fn (cf &CFlag) eval() string {
 				sparams := remainder[cflag.fexisting_literal.len + 1..].all_before(')')
 				i += sparams.len + cflag.fexisting_literal.len + 1
 				svalues := sparams.replace(',', '\n').split_into_lines().map(it.trim(' \'"'))
-				mut found_spath := ''
+				// mut found_spath := ''
 				for spath in svalues {
 					if os.exists(spath) {
-						found_spath = spath
+						// found_spath = spath
 						value += spath
 						continue cflag_eval_outer_loop
 					}

vlib/v/checker/checker.v

@@ -119,7 +119,7 @@ pub fn (mut c Checker) check_scope_vars(sc &ast.Scope) {
 		match obj {
 			ast.Var {
 				if !c.pref.is_repl {
-					if !obj.is_used && obj.name[0] != `_` {
+					if !obj.is_used && obj.name[0] != `_` && !c.file.is_test {
 						c.warn('unused variable: `$obj.name`', obj.pos)
 					}
 				}
@@ -2570,7 +2570,10 @@ pub fn (mut c Checker) selector_expr(mut selector_expr ast.SelectorExpr) ast.Typ
 	//
 	c.using_new_err_struct = using_new_err_struct_save
 	if typ == ast.void_type_idx {
-		c.error('unknown selector expression', selector_expr.pos)
+		// This means that the variable's value was assigned to an
+		// unknown function or method, so the error was already handled
+		// earlier
+		// c.error('unknown selector expression', selector_expr.pos)
 		return ast.void_type
 	}
 	selector_expr.expr_type = typ
@@ -3644,7 +3647,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 fn (mut c Checker) assert_stmt(node ast.AssertStmt) {
 	cur_exp_typ := c.expected_type
 	assert_type := c.check_expr_opt_call(node.expr, c.expr(node.expr))
-	if assert_type != ast.bool_type_idx {
+	if assert_type != ast.bool_type_idx && assert_type != ast.void_type_idx {
 		atype_name := c.table.get_type_symbol(assert_type).name
 		c.error('assert can be used only with `bool` expressions, but found `$atype_name` instead',
 			node.pos)
@@ -4763,7 +4766,7 @@ pub fn (mut c Checker) ident(mut ident ast.Ident) ast.Type {
 				}
 				ast.Var {
 					// incase var was not marked as used yet (vweb tmpl)
-					obj.is_used = true
+					// obj.is_used = true
 					if ident.pos.pos < obj.pos.pos {
 						c.error('undefined variable `$ident.name` (used before declaration)',
 							ident.pos)

vlib/v/checker/tests/array_or_map_assign_err.out

@@ -10,10 +10,10 @@ vlib/v/checker/tests/array_or_map_assign_err.vv:5:5: error: use `array2 = array1
     4 |     mut a3 := []int{}
     5 |     a3 = a1
       |        ^
-    6 |
+    6 | 
     7 |     m1 := {'one': 1}
 vlib/v/checker/tests/array_or_map_assign_err.vv:8:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
-    6 |
+    6 | 
     7 |     m1 := {'one': 1}
     8 |     m2 := m1
       |           ~~
@@ -24,12 +24,12 @@ vlib/v/checker/tests/array_or_map_assign_err.vv:10:7: error: cannot copy map: ca
     9 |     mut m3 := map[string]int{}
    10 |     m3 = m1
       |          ~~
-   11 |
+   11 | 
    12 |     _ = a2
-vlib/v/checker/tests/array_or_map_assign_err.vv:20:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
-   18 |
-   19 | fn foo(mut m map[string]int) {
-   20 |     m2 := m
+vlib/v/checker/tests/array_or_map_assign_err.vv:25:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
+   23 | 
+   24 | fn foo(mut m map[string]int) {
+   25 |     m2 := m
       |           ^
-   21 |     m['foo'] = 100
-   22 |     println(m)
+   26 |     m['foo'] = 100
+   27 |     println(m)

vlib/v/checker/tests/array_or_map_assign_err.vv

@@ -14,6 +14,11 @@ fn main() {
 
 	mut m := {'foo':1}
 	foo(mut m)
+
+	_ = a3
+	_ = m1
+	_ = m2
+	_ = m3
 }
 
 fn foo(mut m map[string]int) {

vlib/v/checker/tests/arrow_op_wrong_left_type_err_b.out

@@ -3,4 +3,5 @@ vlib/v/checker/tests/arrow_op_wrong_left_type_err_b.vv:4:8: error: cannot assign
     3 |     mut obj := 9
     4 |     obj = <-ch
       |           ~~
-    5 | }
+    5 |     _ = obj
+    6 | }