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checker: add a check for unused `x << y` expressions (where x != array) (#12586)

pull/12588/head
Delyan Angelov 2021-11-27 07:38:35 +02:00 committed by GitHub
parent 12585e88e1
commit deaeffc4db
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3 changed files with 192 additions and 16 deletions
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117
vlib/v/checker/checker.v
View File

@ -85,6 +85,12 @@ pub mut:
fn_level int // 0 for the top level, 1 for `fn abc() {}`, 2 for a nested fn, etc
ct_cond_stack []ast.Expr
mut:
stmt_level int // the nesting level inside each stmts list;
// .stmt_level is used to check for `evaluated but not used` ExprStmts like `1 << 1`
// 1 for statements directly at each inner scope level;
// increases for `x := if cond { statement_list1} else {statement_list2}`;
// increases for `x := optfn() or { statement_list3 }`;
is_last_stmt bool
files []ast.File
expr_level int // to avoid infinite recursion segfaults due to compiler bugs
inside_sql bool // to handle sql table fields pseudo variables
@ -121,8 +127,40 @@ pub fn new_checker(table &ast.Table, pref &pref.Preferences) &Checker {
}
}
fn (mut c Checker) reset_checker_state_at_start_of_new_file() {
c.expected_type = ast.void_type
c.expected_or_type = ast.void_type
c.const_decl = ''
c.in_for_count = 0
c.returns = false
c.scope_returns = false
c.mod = ''
c.is_builtin_mod = false
c.inside_unsafe = false
c.inside_const = false
c.inside_anon_fn = false
c.inside_ref_lit = false
c.inside_defer = false
c.inside_fn_arg = false
c.inside_ct_attr = false
c.skip_flags = false
c.fn_level = 0
c.expr_level = 0
c.stmt_level = 0
c.inside_sql = false
c.cur_orm_ts = ast.TypeSymbol{}
c.prevent_sum_type_unwrapping_once = false
c.loop_label = ''
c.using_new_err_struct = false
c.inside_selector_expr = false
c.inside_println_arg = false
c.inside_decl_rhs = false
c.inside_if_guard = false
}
pub fn (mut c Checker) check(ast_file_ &ast.File) {
mut ast_file := ast_file_
c.reset_checker_state_at_start_of_new_file()
c.change_current_file(ast_file)
for i, ast_import in ast_file.imports {
for sym in ast_import.syms {
@ -139,6 +177,7 @@ pub fn (mut c Checker) check(ast_file_ &ast.File) {
}
}
}
c.stmt_level = 0
for mut stmt in ast_file.stmts {
if stmt in [ast.ConstDecl, ast.ExprStmt] {
c.expr_level = 0
@ -148,6 +187,8 @@ pub fn (mut c Checker) check(ast_file_ &ast.File) {
return
}
}
//
c.stmt_level = 0
for mut stmt in ast_file.stmts {
if stmt is ast.GlobalDecl {
c.expr_level = 0
@ -157,6 +198,8 @@ pub fn (mut c Checker) check(ast_file_ &ast.File) {
return
}
}
//
c.stmt_level = 0
for mut stmt in ast_file.stmts {
if stmt !is ast.ConstDecl && stmt !is ast.GlobalDecl && stmt !is ast.ExprStmt {
c.expr_level = 0
@ -166,6 +209,7 @@ pub fn (mut c Checker) check(ast_file_ &ast.File) {
return
}
}
//
c.check_scope_vars(c.file.scope)
}
@ -4654,7 +4698,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
}
}
c.inside_defer = true
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.inside_defer = false
}
ast.EnumDecl {
@ -4679,6 +4723,16 @@ fn (mut c Checker) stmt(node ast.Stmt) {
}
else {}
}
if !c.pref.is_repl && (c.stmt_level == 1 || (c.stmt_level > 1 && !c.is_last_stmt)) {
if node.expr is ast.InfixExpr {
if node.expr.op == .left_shift {
left_sym := c.table.get_final_type_symbol(node.expr.left_type)
if left_sym.kind != .array {
c.error('unused expression', node.pos)
}
}
}
}
c.check_expr_opt_call(node.expr, or_typ)
// TODO This should work, even if it's prolly useless .-.
// node.typ = c.check_expr_opt_call(node.expr, ast.void_type)
@ -4757,10 +4811,10 @@ fn (mut c Checker) assert_stmt(node ast.AssertStmt) {
fn (mut c Checker) block(node ast.Block) {
if node.is_unsafe {
c.inside_unsafe = true
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.inside_unsafe = false
} else {
c.stmts(node.stmts)
c.stmts_list(node.stmts)
}
}
@ -4789,7 +4843,7 @@ fn (mut c Checker) for_c_stmt(node ast.ForCStmt) {
c.stmt(node.inc)
}
c.check_loop_label(node.label, node.pos)
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.loop_label = prev_loop_label
c.in_for_count--
}
@ -4803,7 +4857,7 @@ fn (mut c Checker) comptime_for(node ast.ComptimeFor) {
if node.kind == .fields {
c.comptime_fields_type[node.val_var] = node.typ
}
c.stmts(node.stmts)
c.stmts_list(node.stmts)
}
fn (mut c Checker) for_in_stmt(mut node ast.ForInStmt) {
@ -4913,7 +4967,7 @@ fn (mut c Checker) for_in_stmt(mut node ast.ForInStmt) {
}
}
c.check_loop_label(node.label, node.pos)
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.loop_label = prev_loop_label
c.in_for_count--
}
@ -4949,7 +5003,7 @@ fn (mut c Checker) for_stmt(mut node ast.ForStmt) {
// TODO: update loop var type
// how does this work currenly?
c.check_loop_label(node.label, node.pos)
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.loop_label = prev_loop_label
c.in_for_count--
}
@ -5252,12 +5306,24 @@ fn (mut c Checker) import_stmt(node ast.Import) {
}
}
// stmts_list is the same as .stmts(), but it should be called for top level statements in the inner scope
fn (mut c Checker) stmts_list(stmts []ast.Stmt) {
old_stmt_level := c.stmt_level
c.stmt_level = 0
c.stmts(stmts)
c.stmt_level = old_stmt_level
}
// stmts processes a list of statements. It can be called even for a list of statements that end with an expression,
// For example for the or block in `x := opt() or { stmt1 stmt2 ExprStmt }`
fn (mut c Checker) stmts(stmts []ast.Stmt) {
mut unreachable := token.Position{
line_nr: -1
}
c.expected_type = ast.void_type
for stmt in stmts {
c.stmt_level++
for i, stmt in stmts {
c.is_last_stmt = i == stmts.len - 1
if c.scope_returns {
if unreachable.line_nr == -1 {
unreachable = stmt.pos
@ -5271,6 +5337,7 @@ fn (mut c Checker) stmts(stmts []ast.Stmt) {
c.scope_returns = false
}
}
c.stmt_level--
if unreachable.line_nr >= 0 {
c.error('unreachable code', unreachable)
}
@ -6171,7 +6238,11 @@ pub fn (mut c Checker) match_expr(mut node ast.MatchExpr) ast.Type {
mut nbranches_with_return := 0
mut nbranches_without_return := 0
for branch in node.branches {
c.stmts(branch.stmts)
if node.is_expr {
c.stmts(branch.stmts)
} else {
c.stmts_list(branch.stmts)
}
if node.is_expr {
if branch.stmts.len > 0 {
// ignore last statement - workaround
@ -6616,7 +6687,7 @@ pub fn (mut c Checker) select_expr(mut node ast.SelectExpr) ast.Type {
}
}
}
c.stmts(branch.stmts)
c.stmts_list(branch.stmts)
}
return ast.bool_type
}
@ -6644,7 +6715,7 @@ pub fn (mut c Checker) lock_expr(mut node ast.LockExpr) ast.Type {
c.locked_names << id_name
}
}
c.stmts(node.stmts)
c.stmts_list(node.stmts)
c.rlocked_names = []
c.locked_names = []
// handle `x := rlock a { a.getval() }`
@ -6817,7 +6888,11 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
c.ct_cond_stack << branch.cond
}
if !c.skip_flags {
c.stmts(branch.stmts)
if node_is_expr {
c.stmts(branch.stmts)
} else {
c.stmts_list(branch.stmts)
}
} else if c.pref.output_cross_c {
mut is_freestanding_block := false
if branch.cond is ast.Ident {
@ -6829,7 +6904,11 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
branch.stmts = []
node.branches[i].stmts = []
}
c.stmts(branch.stmts)
if node_is_expr {
c.stmts(branch.stmts)
} else {
c.stmts_list(branch.stmts)
}
} else if !is_comptime_type_is_expr {
node.branches[i].stmts = []
}
@ -6843,7 +6922,11 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
} else {
// smartcast sumtypes and interfaces when using `is`
c.smartcast_if_conds(branch.cond, mut branch.scope)
c.stmts(branch.stmts)
if node_is_expr {
c.stmts(branch.stmts)
} else {
c.stmts_list(branch.stmts)
}
}
if expr_required {
if branch.stmts.len > 0 && branch.stmts[branch.stmts.len - 1] is ast.ExprStmt {
@ -8107,12 +8190,14 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
prev_inside_unsafe := c.inside_unsafe
prev_inside_anon_fn := c.inside_anon_fn
prev_returns := c.returns
prev_stmt_level := c.stmt_level
c.fn_level++
c.in_for_count = 0
c.inside_defer = false
c.inside_unsafe = false
c.returns = false
defer {
c.stmt_level = prev_stmt_level
c.fn_level--
c.returns = prev_returns
c.inside_anon_fn = prev_inside_anon_fn
@ -8372,7 +8457,7 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
}
}
c.fn_scope = node.scope
c.stmts(node.stmts)
c.stmts_list(node.stmts)
node_has_top_return := has_top_return(node.stmts)
node.has_return = c.returns || node_has_top_return
c.check_noreturn_fn_decl(mut node)
@ -8406,7 +8491,7 @@ fn (mut c Checker) anon_fn(mut node ast.AnonFn) ast.Type {
}
var.typ = parent_var.typ
}
c.stmts(node.decl.stmts)
c.stmts_list(node.decl.stmts)
c.fn_decl(mut node.decl)
return node.typ
}

49
vlib/v/checker/tests/left_shift_op_expr_not_used.out 100644
View File

@ -0,0 +1,49 @@
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:4:2: error: unused expression
2 | mut a := 12
3 | mut arr := []int{}
4 | a << 1
| ~~~~~~
5 | if true {
6 | a << 2
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:6:3: error: unused expression
4 | a << 1
5 | if true {
6 | a << 2
| ~~~~~~
7 | }
8 | c := if true { a << 111 } else { a << 333 }
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:10:2: error: unused expression
8 | c := if true { a << 111 } else { a << 333 }
9 | println(c)
10 | a << 1
| ~~~~~~
11 | println(a)
12 | 5 << 9
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:12:2: error: unused expression
10 | a << 1
11 | println(a)
12 | 5 << 9
| ~~~~~~
13 | for i in 0 .. 10 {
14 | z := i << 5
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:15:3: error: unused expression
13 | for i in 0 .. 10 {
14 | z := i << 5
15 | i << 5
| ~~~~~~
16 | println(z)
17 | }
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:33:3: error: unused expression
31 | //
32 | x := if true {
33 | a << 1
| ~~~~~~
34 | 999
35 | } else {
vlib/v/checker/tests/left_shift_op_expr_not_used.vv:37:3: error: unused expression
35 | } else {
36 | println('---')
37 | a << 9999
| ~~~~~~~~~
38 | println('---')
39 | 555

42
vlib/v/checker/tests/left_shift_op_expr_not_used.vv 100644
View File

@ -0,0 +1,42 @@
fn main() {
mut a := 12
mut arr := []int{}
a << 1
if true {
a << 2
}
c := if true { a << 111 } else { a << 333 }
println(c)
a << 1
println(a)
5 << 9
for i in 0 .. 10 {
z := i << 5
i << 5
println(z)
}
//
arr << 1
if true {
arr << 2
}
d := if true {
arr << 111
777
} else {
arr << 333
999
}
println(d)
//
x := if true {
a << 1
999
} else {
println('---')
a << 9999
println('---')
555
}
println(x)
}