511 lines
18 KiB
Rust
511 lines
18 KiB
Rust
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
|
|
use clippy_utils::source::snippet_opt;
|
|
use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
|
|
use clippy_utils::{eq_expr_value, get_trait_def_id, in_macro, paths};
|
|
use if_chain::if_chain;
|
|
use rustc_ast::ast::LitKind;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
|
|
use rustc_hir::{BinOpKind, Body, Expr, ExprKind, FnDecl, HirId, UnOp};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::hir::map::Map;
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
use rustc_span::source_map::Span;
|
|
use rustc_span::sym;
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for boolean expressions that can be written more
|
|
/// concisely.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// Readability of boolean expressions suffers from
|
|
/// unnecessary duplication.
|
|
///
|
|
/// ### Known problems
|
|
/// Ignores short circuiting behavior of `||` and
|
|
/// `&&`. Ignores `|`, `&` and `^`.
|
|
///
|
|
/// ### Example
|
|
/// ```ignore
|
|
/// if a && true // should be: if a
|
|
/// if !(a == b) // should be: if a != b
|
|
/// ```
|
|
pub NONMINIMAL_BOOL,
|
|
complexity,
|
|
"boolean expressions that can be written more concisely"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for boolean expressions that contain terminals that
|
|
/// can be eliminated.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// This is most likely a logic bug.
|
|
///
|
|
/// ### Known problems
|
|
/// Ignores short circuiting behavior.
|
|
///
|
|
/// ### Example
|
|
/// ```ignore
|
|
/// if a && b || a { ... }
|
|
/// ```
|
|
/// The `b` is unnecessary, the expression is equivalent to `if a`.
|
|
pub LOGIC_BUG,
|
|
correctness,
|
|
"boolean expressions that contain terminals which can be eliminated"
|
|
}
|
|
|
|
// For each pairs, both orders are considered.
|
|
const METHODS_WITH_NEGATION: [(&str, &str); 2] = [("is_some", "is_none"), ("is_err", "is_ok")];
|
|
|
|
declare_lint_pass!(NonminimalBool => [NONMINIMAL_BOOL, LOGIC_BUG]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for NonminimalBool {
|
|
fn check_fn(
|
|
&mut self,
|
|
cx: &LateContext<'tcx>,
|
|
_: FnKind<'tcx>,
|
|
_: &'tcx FnDecl<'_>,
|
|
body: &'tcx Body<'_>,
|
|
_: Span,
|
|
_: HirId,
|
|
) {
|
|
NonminimalBoolVisitor { cx }.visit_body(body);
|
|
}
|
|
}
|
|
|
|
struct NonminimalBoolVisitor<'a, 'tcx> {
|
|
cx: &'a LateContext<'tcx>,
|
|
}
|
|
|
|
use quine_mc_cluskey::Bool;
|
|
struct Hir2Qmm<'a, 'tcx, 'v> {
|
|
terminals: Vec<&'v Expr<'v>>,
|
|
cx: &'a LateContext<'tcx>,
|
|
}
|
|
|
|
impl<'a, 'tcx, 'v> Hir2Qmm<'a, 'tcx, 'v> {
|
|
fn extract(&mut self, op: BinOpKind, a: &[&'v Expr<'_>], mut v: Vec<Bool>) -> Result<Vec<Bool>, String> {
|
|
for a in a {
|
|
if let ExprKind::Binary(binop, lhs, rhs) = &a.kind {
|
|
if binop.node == op {
|
|
v = self.extract(op, &[lhs, rhs], v)?;
|
|
continue;
|
|
}
|
|
}
|
|
v.push(self.run(a)?);
|
|
}
|
|
Ok(v)
|
|
}
|
|
|
|
fn run(&mut self, e: &'v Expr<'_>) -> Result<Bool, String> {
|
|
fn negate(bin_op_kind: BinOpKind) -> Option<BinOpKind> {
|
|
match bin_op_kind {
|
|
BinOpKind::Eq => Some(BinOpKind::Ne),
|
|
BinOpKind::Ne => Some(BinOpKind::Eq),
|
|
BinOpKind::Gt => Some(BinOpKind::Le),
|
|
BinOpKind::Ge => Some(BinOpKind::Lt),
|
|
BinOpKind::Lt => Some(BinOpKind::Ge),
|
|
BinOpKind::Le => Some(BinOpKind::Gt),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
// prevent folding of `cfg!` macros and the like
|
|
if !e.span.from_expansion() {
|
|
match &e.kind {
|
|
ExprKind::Unary(UnOp::Not, inner) => return Ok(Bool::Not(Box::new(self.run(inner)?))),
|
|
ExprKind::Binary(binop, lhs, rhs) => match &binop.node {
|
|
BinOpKind::Or => {
|
|
return Ok(Bool::Or(self.extract(BinOpKind::Or, &[lhs, rhs], Vec::new())?));
|
|
},
|
|
BinOpKind::And => {
|
|
return Ok(Bool::And(self.extract(BinOpKind::And, &[lhs, rhs], Vec::new())?));
|
|
},
|
|
_ => (),
|
|
},
|
|
ExprKind::Lit(lit) => match lit.node {
|
|
LitKind::Bool(true) => return Ok(Bool::True),
|
|
LitKind::Bool(false) => return Ok(Bool::False),
|
|
_ => (),
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|
|
for (n, expr) in self.terminals.iter().enumerate() {
|
|
if eq_expr_value(self.cx, e, expr) {
|
|
#[allow(clippy::cast_possible_truncation)]
|
|
return Ok(Bool::Term(n as u8));
|
|
}
|
|
|
|
if_chain! {
|
|
if let ExprKind::Binary(e_binop, e_lhs, e_rhs) = &e.kind;
|
|
if implements_ord(self.cx, e_lhs);
|
|
if let ExprKind::Binary(expr_binop, expr_lhs, expr_rhs) = &expr.kind;
|
|
if negate(e_binop.node) == Some(expr_binop.node);
|
|
if eq_expr_value(self.cx, e_lhs, expr_lhs);
|
|
if eq_expr_value(self.cx, e_rhs, expr_rhs);
|
|
then {
|
|
#[allow(clippy::cast_possible_truncation)]
|
|
return Ok(Bool::Not(Box::new(Bool::Term(n as u8))));
|
|
}
|
|
}
|
|
}
|
|
let n = self.terminals.len();
|
|
self.terminals.push(e);
|
|
if n < 32 {
|
|
#[allow(clippy::cast_possible_truncation)]
|
|
Ok(Bool::Term(n as u8))
|
|
} else {
|
|
Err("too many literals".to_owned())
|
|
}
|
|
}
|
|
}
|
|
|
|
struct SuggestContext<'a, 'tcx, 'v> {
|
|
terminals: &'v [&'v Expr<'v>],
|
|
cx: &'a LateContext<'tcx>,
|
|
output: String,
|
|
}
|
|
|
|
impl<'a, 'tcx, 'v> SuggestContext<'a, 'tcx, 'v> {
|
|
fn recurse(&mut self, suggestion: &Bool) -> Option<()> {
|
|
use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
|
|
match suggestion {
|
|
True => {
|
|
self.output.push_str("true");
|
|
},
|
|
False => {
|
|
self.output.push_str("false");
|
|
},
|
|
Not(inner) => match **inner {
|
|
And(_) | Or(_) => {
|
|
self.output.push('!');
|
|
self.output.push('(');
|
|
self.recurse(inner);
|
|
self.output.push(')');
|
|
},
|
|
Term(n) => {
|
|
let terminal = self.terminals[n as usize];
|
|
if let Some(str) = simplify_not(self.cx, terminal) {
|
|
self.output.push_str(&str);
|
|
} else {
|
|
self.output.push('!');
|
|
let snip = snippet_opt(self.cx, terminal.span)?;
|
|
self.output.push_str(&snip);
|
|
}
|
|
},
|
|
True | False | Not(_) => {
|
|
self.output.push('!');
|
|
self.recurse(inner)?;
|
|
},
|
|
},
|
|
And(v) => {
|
|
for (index, inner) in v.iter().enumerate() {
|
|
if index > 0 {
|
|
self.output.push_str(" && ");
|
|
}
|
|
if let Or(_) = *inner {
|
|
self.output.push('(');
|
|
self.recurse(inner);
|
|
self.output.push(')');
|
|
} else {
|
|
self.recurse(inner);
|
|
}
|
|
}
|
|
},
|
|
Or(v) => {
|
|
for (index, inner) in v.iter().rev().enumerate() {
|
|
if index > 0 {
|
|
self.output.push_str(" || ");
|
|
}
|
|
self.recurse(inner);
|
|
}
|
|
},
|
|
&Term(n) => {
|
|
let snip = snippet_opt(self.cx, self.terminals[n as usize].span)?;
|
|
self.output.push_str(&snip);
|
|
},
|
|
}
|
|
Some(())
|
|
}
|
|
}
|
|
|
|
fn simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
|
|
match &expr.kind {
|
|
ExprKind::Binary(binop, lhs, rhs) => {
|
|
if !implements_ord(cx, lhs) {
|
|
return None;
|
|
}
|
|
|
|
match binop.node {
|
|
BinOpKind::Eq => Some(" != "),
|
|
BinOpKind::Ne => Some(" == "),
|
|
BinOpKind::Lt => Some(" >= "),
|
|
BinOpKind::Gt => Some(" <= "),
|
|
BinOpKind::Le => Some(" > "),
|
|
BinOpKind::Ge => Some(" < "),
|
|
_ => None,
|
|
}
|
|
.and_then(|op| {
|
|
Some(format!(
|
|
"{}{}{}",
|
|
snippet_opt(cx, lhs.span)?,
|
|
op,
|
|
snippet_opt(cx, rhs.span)?
|
|
))
|
|
})
|
|
},
|
|
ExprKind::MethodCall(path, _, args, _) if args.len() == 1 => {
|
|
let type_of_receiver = cx.typeck_results().expr_ty(&args[0]);
|
|
if !is_type_diagnostic_item(cx, type_of_receiver, sym::Option)
|
|
&& !is_type_diagnostic_item(cx, type_of_receiver, sym::Result)
|
|
{
|
|
return None;
|
|
}
|
|
METHODS_WITH_NEGATION
|
|
.iter()
|
|
.copied()
|
|
.flat_map(|(a, b)| vec![(a, b), (b, a)])
|
|
.find(|&(a, _)| {
|
|
let path: &str = &path.ident.name.as_str();
|
|
a == path
|
|
})
|
|
.and_then(|(_, neg_method)| Some(format!("{}.{}()", snippet_opt(cx, args[0].span)?, neg_method)))
|
|
},
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
fn suggest(cx: &LateContext<'_>, suggestion: &Bool, terminals: &[&Expr<'_>]) -> String {
|
|
let mut suggest_context = SuggestContext {
|
|
terminals,
|
|
cx,
|
|
output: String::new(),
|
|
};
|
|
suggest_context.recurse(suggestion);
|
|
suggest_context.output
|
|
}
|
|
|
|
fn simple_negate(b: Bool) -> Bool {
|
|
use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
|
|
match b {
|
|
True => False,
|
|
False => True,
|
|
t @ Term(_) => Not(Box::new(t)),
|
|
And(mut v) => {
|
|
for el in &mut v {
|
|
*el = simple_negate(::std::mem::replace(el, True));
|
|
}
|
|
Or(v)
|
|
},
|
|
Or(mut v) => {
|
|
for el in &mut v {
|
|
*el = simple_negate(::std::mem::replace(el, True));
|
|
}
|
|
And(v)
|
|
},
|
|
Not(inner) => *inner,
|
|
}
|
|
}
|
|
|
|
#[derive(Default)]
|
|
struct Stats {
|
|
terminals: [usize; 32],
|
|
negations: usize,
|
|
ops: usize,
|
|
}
|
|
|
|
fn terminal_stats(b: &Bool) -> Stats {
|
|
fn recurse(b: &Bool, stats: &mut Stats) {
|
|
match b {
|
|
True | False => stats.ops += 1,
|
|
Not(inner) => {
|
|
match **inner {
|
|
And(_) | Or(_) => stats.ops += 1, // brackets are also operations
|
|
_ => stats.negations += 1,
|
|
}
|
|
recurse(inner, stats);
|
|
},
|
|
And(v) | Or(v) => {
|
|
stats.ops += v.len() - 1;
|
|
for inner in v {
|
|
recurse(inner, stats);
|
|
}
|
|
},
|
|
&Term(n) => stats.terminals[n as usize] += 1,
|
|
}
|
|
}
|
|
use quine_mc_cluskey::Bool::{And, False, Not, Or, Term, True};
|
|
let mut stats = Stats::default();
|
|
recurse(b, &mut stats);
|
|
stats
|
|
}
|
|
|
|
impl<'a, 'tcx> NonminimalBoolVisitor<'a, 'tcx> {
|
|
fn bool_expr(&self, e: &'tcx Expr<'_>) {
|
|
let mut h2q = Hir2Qmm {
|
|
terminals: Vec::new(),
|
|
cx: self.cx,
|
|
};
|
|
if let Ok(expr) = h2q.run(e) {
|
|
if h2q.terminals.len() > 8 {
|
|
// QMC has exponentially slow behavior as the number of terminals increases
|
|
// 8 is reasonable, it takes approximately 0.2 seconds.
|
|
// See #825
|
|
return;
|
|
}
|
|
|
|
let stats = terminal_stats(&expr);
|
|
let mut simplified = expr.simplify();
|
|
for simple in Bool::Not(Box::new(expr)).simplify() {
|
|
match simple {
|
|
Bool::Not(_) | Bool::True | Bool::False => {},
|
|
_ => simplified.push(Bool::Not(Box::new(simple.clone()))),
|
|
}
|
|
let simple_negated = simple_negate(simple);
|
|
if simplified.iter().any(|s| *s == simple_negated) {
|
|
continue;
|
|
}
|
|
simplified.push(simple_negated);
|
|
}
|
|
let mut improvements = Vec::with_capacity(simplified.len());
|
|
'simplified: for suggestion in &simplified {
|
|
let simplified_stats = terminal_stats(suggestion);
|
|
let mut improvement = false;
|
|
for i in 0..32 {
|
|
// ignore any "simplifications" that end up requiring a terminal more often
|
|
// than in the original expression
|
|
if stats.terminals[i] < simplified_stats.terminals[i] {
|
|
continue 'simplified;
|
|
}
|
|
if stats.terminals[i] != 0 && simplified_stats.terminals[i] == 0 {
|
|
span_lint_and_then(
|
|
self.cx,
|
|
LOGIC_BUG,
|
|
e.span,
|
|
"this boolean expression contains a logic bug",
|
|
|diag| {
|
|
diag.span_help(
|
|
h2q.terminals[i].span,
|
|
"this expression can be optimized out by applying boolean operations to the \
|
|
outer expression",
|
|
);
|
|
diag.span_suggestion(
|
|
e.span,
|
|
"it would look like the following",
|
|
suggest(self.cx, suggestion, &h2q.terminals),
|
|
// nonminimal_bool can produce minimal but
|
|
// not human readable expressions (#3141)
|
|
Applicability::Unspecified,
|
|
);
|
|
},
|
|
);
|
|
// don't also lint `NONMINIMAL_BOOL`
|
|
return;
|
|
}
|
|
// if the number of occurrences of a terminal decreases or any of the stats
|
|
// decreases while none increases
|
|
improvement |= (stats.terminals[i] > simplified_stats.terminals[i])
|
|
|| (stats.negations > simplified_stats.negations && stats.ops == simplified_stats.ops)
|
|
|| (stats.ops > simplified_stats.ops && stats.negations == simplified_stats.negations);
|
|
}
|
|
if improvement {
|
|
improvements.push(suggestion);
|
|
}
|
|
}
|
|
let nonminimal_bool_lint = |suggestions: Vec<_>| {
|
|
span_lint_and_then(
|
|
self.cx,
|
|
NONMINIMAL_BOOL,
|
|
e.span,
|
|
"this boolean expression can be simplified",
|
|
|diag| {
|
|
diag.span_suggestions(
|
|
e.span,
|
|
"try",
|
|
suggestions.into_iter(),
|
|
// nonminimal_bool can produce minimal but
|
|
// not human readable expressions (#3141)
|
|
Applicability::Unspecified,
|
|
);
|
|
},
|
|
);
|
|
};
|
|
if improvements.is_empty() {
|
|
let mut visitor = NotSimplificationVisitor { cx: self.cx };
|
|
visitor.visit_expr(e);
|
|
} else {
|
|
nonminimal_bool_lint(
|
|
improvements
|
|
.into_iter()
|
|
.map(|suggestion| suggest(self.cx, suggestion, &h2q.terminals))
|
|
.collect(),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> Visitor<'tcx> for NonminimalBoolVisitor<'a, 'tcx> {
|
|
type Map = Map<'tcx>;
|
|
|
|
fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
|
|
if in_macro(e.span) {
|
|
return;
|
|
}
|
|
match &e.kind {
|
|
ExprKind::Binary(binop, _, _) if binop.node == BinOpKind::Or || binop.node == BinOpKind::And => {
|
|
self.bool_expr(e);
|
|
},
|
|
ExprKind::Unary(UnOp::Not, inner) => {
|
|
if self.cx.typeck_results().node_types()[inner.hir_id].is_bool() {
|
|
self.bool_expr(e);
|
|
} else {
|
|
walk_expr(self, e);
|
|
}
|
|
},
|
|
_ => walk_expr(self, e),
|
|
}
|
|
}
|
|
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
|
NestedVisitorMap::None
|
|
}
|
|
}
|
|
|
|
fn implements_ord<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> bool {
|
|
let ty = cx.typeck_results().expr_ty(expr);
|
|
get_trait_def_id(cx, &paths::ORD).map_or(false, |id| implements_trait(cx, ty, id, &[]))
|
|
}
|
|
|
|
struct NotSimplificationVisitor<'a, 'tcx> {
|
|
cx: &'a LateContext<'tcx>,
|
|
}
|
|
|
|
impl<'a, 'tcx> Visitor<'tcx> for NotSimplificationVisitor<'a, 'tcx> {
|
|
type Map = Map<'tcx>;
|
|
|
|
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
|
|
if let ExprKind::Unary(UnOp::Not, inner) = &expr.kind {
|
|
if let Some(suggestion) = simplify_not(self.cx, inner) {
|
|
span_lint_and_sugg(
|
|
self.cx,
|
|
NONMINIMAL_BOOL,
|
|
expr.span,
|
|
"this boolean expression can be simplified",
|
|
"try",
|
|
suggestion,
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
|
|
walk_expr(self, expr);
|
|
}
|
|
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
|
NestedVisitorMap::None
|
|
}
|
|
}
|