-use rustc::hir::def_id::DefId;
-use rustc::hir::intravisit::{Visitor, walk_expr, NestedVisitorMap};
+use crate::utils::{get_parent_expr, span_lint, span_note_and_lint};
+use if_chain::if_chain;
+use rustc::declare_lint_pass;
+use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc::hir::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::ty;
-use rustc::lint::*;
-use utils::{get_parent_expr, span_note_and_lint, span_lint};
+use rustc_session::declare_tool_lint;
-/// **What it does:** Checks for a read and a write to the same variable where
-/// whether the read occurs before or after the write depends on the evaluation
-/// order of sub-expressions.
-///
-/// **Why is this bad?** It is often confusing to read. In addition, the
-/// sub-expression evaluation order for Rust is not well documented.
-///
-/// **Known problems:** Code which intentionally depends on the evaluation
-/// order, or which is correct for any evaluation order.
-///
-/// **Example:**
-/// ```rust
-/// let mut x = 0;
-/// let a = {x = 1; 1} + x;
-/// // Unclear whether a is 1 or 2.
-/// ```
-declare_lint! {
+declare_clippy_lint! {
+ /// **What it does:** Checks for a read and a write to the same variable where
+ /// whether the read occurs before or after the write depends on the evaluation
+ /// order of sub-expressions.
+ ///
+ /// **Why is this bad?** It is often confusing to read. In addition, the
+ /// sub-expression evaluation order for Rust is not well documented.
+ ///
+ /// **Known problems:** Code which intentionally depends on the evaluation
+ /// order, or which is correct for any evaluation order.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// let mut x = 0;
+ /// let a = {
+ /// x = 1;
+ /// 1
+ /// } + x;
+ /// // Unclear whether a is 1 or 2.
+ /// ```
pub EVAL_ORDER_DEPENDENCE,
- Warn,
+ complexity,
"whether a variable read occurs before a write depends on sub-expression evaluation order"
}
-/// **What it does:** Checks for diverging calls that are not match arms or statements.
-///
-/// **Why is this bad?** It is often confusing to read. In addition, the
-/// sub-expression evaluation order for Rust is not well documented.
-///
-/// **Known problems:** Someone might want to use `some_bool || panic!()` as a shorthand.
-///
-/// **Example:**
-/// ```rust
-/// let a = b() || panic!() || c();
-/// // `c()` is dead, `panic!()` is only called if `b()` returns `false`
-/// let x = (a, b, c, panic!());
-/// // can simply be replaced by `panic!()`
-/// ```
-declare_lint! {
+declare_clippy_lint! {
+ /// **What it does:** Checks for diverging calls that are not match arms or
+ /// statements.
+ ///
+ /// **Why is this bad?** It is often confusing to read. In addition, the
+ /// sub-expression evaluation order for Rust is not well documented.
+ ///
+ /// **Known problems:** Someone might want to use `some_bool || panic!()` as a
+ /// shorthand.
+ ///
+ /// **Example:**
+ /// ```rust,no_run
+ /// # fn b() -> bool { true }
+ /// # fn c() -> bool { true }
+ /// let a = b() || panic!() || c();
+ /// // `c()` is dead, `panic!()` is only called if `b()` returns `false`
+ /// let x = (a, b, c, panic!());
+ /// // can simply be replaced by `panic!()`
+ /// ```
pub DIVERGING_SUB_EXPRESSION,
- Warn,
+ complexity,
"whether an expression contains a diverging sub expression"
}
-#[derive(Copy,Clone)]
-pub struct EvalOrderDependence;
-
-impl LintPass for EvalOrderDependence {
- fn get_lints(&self) -> LintArray {
- lint_array!(EVAL_ORDER_DEPENDENCE, DIVERGING_SUB_EXPRESSION)
- }
-}
+declare_lint_pass!(EvalOrderDependence => [EVAL_ORDER_DEPENDENCE, DIVERGING_SUB_EXPRESSION]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EvalOrderDependence {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
// Find a write to a local variable.
- match expr.node {
- ExprAssign(ref lhs, _) |
- ExprAssignOp(_, ref lhs, _) => {
- if let ExprPath(ref qpath) = lhs.node {
+ match expr.kind {
+ ExprKind::Assign(ref lhs, _) | ExprKind::AssignOp(_, ref lhs, _) => {
+ if let ExprKind::Path(ref qpath) = lhs.kind {
if let QPath::Resolved(_, ref path) = *qpath {
if path.segments.len() == 1 {
- let var = cx.tables.qpath_def(qpath, lhs.id).def_id();
- let mut visitor = ReadVisitor {
- cx: cx,
- var: var,
- write_expr: expr,
- last_expr: expr,
- };
- check_for_unsequenced_reads(&mut visitor);
+ if let def::Res::Local(var) = cx.tables.qpath_res(qpath, lhs.hir_id) {
+ let mut visitor = ReadVisitor {
+ cx,
+ var,
+ write_expr: expr,
+ last_expr: expr,
+ };
+ check_for_unsequenced_reads(&mut visitor);
+ }
}
}
}
}
}
fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
- match stmt.node {
- StmtExpr(ref e, _) |
- StmtSemi(ref e, _) => DivergenceVisitor { cx: cx }.maybe_walk_expr(e),
- StmtDecl(ref d, _) => {
- if let DeclLocal(ref local) = d.node {
- if let Local { init: Some(ref e), .. } = **local {
- DivergenceVisitor { cx: cx }.visit_expr(e);
- }
+ match stmt.kind {
+ StmtKind::Local(ref local) => {
+ if let Local { init: Some(ref e), .. } = **local {
+ DivergenceVisitor { cx }.visit_expr(e);
}
},
+ StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
+ StmtKind::Item(..) => {},
}
}
}
-struct DivergenceVisitor<'a, 'tcx: 'a> {
+struct DivergenceVisitor<'a, 'tcx> {
cx: &'a LateContext<'a, 'tcx>,
}
impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
fn maybe_walk_expr(&mut self, e: &'tcx Expr) {
- match e.node {
- ExprClosure(..) => {},
- ExprMatch(ref e, ref arms, _) => {
+ match e.kind {
+ ExprKind::Closure(..) => {},
+ ExprKind::Match(ref e, ref arms, _) => {
self.visit_expr(e);
for arm in arms {
if let Some(ref guard) = arm.guard {
- self.visit_expr(guard);
+ match guard {
+ Guard::If(if_expr) => self.visit_expr(if_expr),
+ }
}
// make sure top level arm expressions aren't linted
self.maybe_walk_expr(&*arm.body);
impl<'a, 'tcx> Visitor<'tcx> for DivergenceVisitor<'a, 'tcx> {
fn visit_expr(&mut self, e: &'tcx Expr) {
- match e.node {
- ExprAgain(_) | ExprBreak(_, _) | ExprRet(_) => self.report_diverging_sub_expr(e),
- ExprCall(ref func, _) => {
- match self.cx.tables.expr_ty(func).sty {
- ty::TyFnDef(_, _, fn_ty) |
- ty::TyFnPtr(fn_ty) => {
- if let ty::TyNever = self.cx.tcx.erase_late_bound_regions(&fn_ty).output().sty {
+ match e.kind {
+ ExprKind::Continue(_) | ExprKind::Break(_, _) | ExprKind::Ret(_) => self.report_diverging_sub_expr(e),
+ ExprKind::Call(ref func, _) => {
+ let typ = self.cx.tables.expr_ty(func);
+ match typ.kind {
+ ty::FnDef(..) | ty::FnPtr(_) => {
+ let sig = typ.fn_sig(self.cx.tcx);
+ if let ty::Never = self.cx.tcx.erase_late_bound_regions(&sig).output().kind {
self.report_diverging_sub_expr(e);
}
},
_ => {},
}
},
- ExprMethodCall(..) => {
+ ExprKind::MethodCall(..) => {
let borrowed_table = self.cx.tables;
if borrowed_table.expr_ty(e).is_never() {
self.report_diverging_sub_expr(e);
}
},
_ => {
- // do not lint expressions referencing objects of type `!`, as that required a diverging expression
+ // do not lint expressions referencing objects of type `!`, as that required a
+ // diverging expression
// to begin with
},
}
/// This means reads for which there is a common ancestor between the read and
/// the write such that
///
-/// * evaluating the ancestor necessarily evaluates both the read and the write
-/// (for example, `&x` and `|| x = 1` don't necessarily evaluate `x`), and
+/// * evaluating the ancestor necessarily evaluates both the read and the write (for example, `&x`
+/// and `|| x = 1` don't necessarily evaluate `x`), and
///
-/// * which one is evaluated first depends on the order of sub-expression
-/// evaluation. Blocks, `if`s, loops, `match`es, and the short-circuiting
-/// logical operators are considered to have a defined evaluation order.
+/// * which one is evaluated first depends on the order of sub-expression evaluation. Blocks, `if`s,
+/// loops, `match`es, and the short-circuiting logical operators are considered to have a defined
+/// evaluation order.
///
/// When such a read is found, the lint is triggered.
-fn check_for_unsequenced_reads(vis: &mut ReadVisitor) {
- let map = &vis.cx.tcx.hir;
- let mut cur_id = vis.write_expr.id;
+fn check_for_unsequenced_reads(vis: &mut ReadVisitor<'_, '_>) {
+ let map = &vis.cx.tcx.hir();
+ let mut cur_id = vis.write_expr.hir_id;
loop {
let parent_id = map.get_parent_node(cur_id);
if parent_id == cur_id {
};
let stop_early = match parent_node {
- map::Node::NodeExpr(expr) => check_expr(vis, expr),
- map::Node::NodeStmt(stmt) => check_stmt(vis, stmt),
- map::Node::NodeItem(_) => {
+ Node::Expr(expr) => check_expr(vis, expr),
+ Node::Stmt(stmt) => check_stmt(vis, stmt),
+ Node::Item(_) => {
// We reached the top of the function, stop.
break;
},
}
fn check_expr<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, expr: &'tcx Expr) -> StopEarly {
- if expr.id == vis.last_expr.id {
+ if expr.hir_id == vis.last_expr.hir_id {
return StopEarly::KeepGoing;
}
- match expr.node {
- ExprArray(_) |
- ExprTup(_) |
- ExprMethodCall(_, _, _) |
- ExprCall(_, _) |
- ExprAssign(_, _) |
- ExprIndex(_, _) |
- ExprRepeat(_, _) |
- ExprStruct(_, _, _) => {
+ match expr.kind {
+ ExprKind::Array(_)
+ | ExprKind::Tup(_)
+ | ExprKind::MethodCall(..)
+ | ExprKind::Call(_, _)
+ | ExprKind::Assign(_, _)
+ | ExprKind::Index(_, _)
+ | ExprKind::Repeat(_, _)
+ | ExprKind::Struct(_, _, _) => {
walk_expr(vis, expr);
},
- ExprBinary(op, _, _) |
- ExprAssignOp(op, _, _) => {
- if op.node == BiAnd || op.node == BiOr {
+ ExprKind::Binary(op, _, _) | ExprKind::AssignOp(op, _, _) => {
+ if op.node == BinOpKind::And || op.node == BinOpKind::Or {
// x && y and x || y always evaluate x first, so these are
// strictly sequenced.
} else {
walk_expr(vis, expr);
}
},
- ExprClosure(_, _, _, _) => {
+ ExprKind::Closure(_, _, _, _, _) => {
// Either
//
- // * `var` is defined in the closure body, in which case we've
- // reached the top of the enclosing function and can stop, or
+ // * `var` is defined in the closure body, in which case we've reached the top of the enclosing
+ // function and can stop, or
//
- // * `var` is captured by the closure, in which case, because
- // evaluating a closure does not evaluate its body, we don't
- // necessarily have a write, so we need to stop to avoid
- // generating false positives.
+ // * `var` is captured by the closure, in which case, because evaluating a closure does not evaluate
+ // its body, we don't necessarily have a write, so we need to stop to avoid generating false
+ // positives.
//
// This is also the only place we need to stop early (grrr).
return StopEarly::Stop;
}
fn check_stmt<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, stmt: &'tcx Stmt) -> StopEarly {
- match stmt.node {
- StmtExpr(ref expr, _) |
- StmtSemi(ref expr, _) => check_expr(vis, expr),
- StmtDecl(ref decl, _) => {
- // If the declaration is of a local variable, check its initializer
- // expression if it has one. Otherwise, keep going.
- let local = match decl.node {
- DeclLocal(ref local) => Some(local),
- _ => None,
- };
- local.and_then(|local| local.init.as_ref())
- .map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr))
- },
+ match stmt.kind {
+ StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => check_expr(vis, expr),
+ // If the declaration is of a local variable, check its initializer
+ // expression if it has one. Otherwise, keep going.
+ StmtKind::Local(ref local) => local
+ .init
+ .as_ref()
+ .map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr)),
+ _ => StopEarly::KeepGoing,
}
}
/// A visitor that looks for reads from a variable.
-struct ReadVisitor<'a, 'tcx: 'a> {
+struct ReadVisitor<'a, 'tcx> {
cx: &'a LateContext<'a, 'tcx>,
- /// The id of the variable we're looking for.
- var: DefId,
+ /// The ID of the variable we're looking for.
+ var: HirId,
/// The expressions where the write to the variable occurred (for reporting
/// in the lint).
write_expr: &'tcx Expr,
impl<'a, 'tcx> Visitor<'tcx> for ReadVisitor<'a, 'tcx> {
fn visit_expr(&mut self, expr: &'tcx Expr) {
- if expr.id == self.last_expr.id {
+ if expr.hir_id == self.last_expr.hir_id {
return;
}
- match expr.node {
- ExprPath(ref qpath) => {
- if let QPath::Resolved(None, ref path) = *qpath {
- if path.segments.len() == 1 && self.cx.tables.qpath_def(qpath, expr.id).def_id() == self.var {
- if is_in_assignment_position(self.cx, expr) {
- // This is a write, not a read.
- } else {
- span_note_and_lint(
- self.cx,
- EVAL_ORDER_DEPENDENCE,
- expr.span,
- "unsequenced read of a variable",
- self.write_expr.span,
- "whether read occurs before this write depends on evaluation order"
- );
- }
+ match expr.kind {
+ ExprKind::Path(ref qpath) => {
+ if_chain! {
+ if let QPath::Resolved(None, ref path) = *qpath;
+ if path.segments.len() == 1;
+ if let def::Res::Local(local_id) = self.cx.tables.qpath_res(qpath, expr.hir_id);
+ if local_id == self.var;
+ // Check that this is a read, not a write.
+ if !is_in_assignment_position(self.cx, expr);
+ then {
+ span_note_and_lint(
+ self.cx,
+ EVAL_ORDER_DEPENDENCE,
+ expr.span,
+ "unsequenced read of a variable",
+ self.write_expr.span,
+ "whether read occurs before this write depends on evaluation order"
+ );
}
}
}
// We're about to descend a closure. Since we don't know when (or
// if) the closure will be evaluated, any reads in it might not
// occur here (or ever). Like above, bail to avoid false positives.
- ExprClosure(_, _, _, _) |
+ ExprKind::Closure(_, _, _, _, _) |
// We want to avoid a false positive when a variable name occurs
// only to have its address taken, so we stop here. Technically,
// ```
//
// TODO: fix this
- ExprAddrOf(_, _) => {
+ ExprKind::AddrOf(_, _, _) => {
return;
}
_ => {}
}
}
-/// Returns true if `expr` is the LHS of an assignment, like `expr = ...`.
-fn is_in_assignment_position(cx: &LateContext, expr: &Expr) -> bool {
+/// Returns `true` if `expr` is the LHS of an assignment, like `expr = ...`.
+fn is_in_assignment_position(cx: &LateContext<'_, '_>, expr: &Expr) -> bool {
if let Some(parent) = get_parent_expr(cx, expr) {
- if let ExprAssign(ref lhs, _) = parent.node {
- return lhs.id == expr.id;
+ if let ExprKind::Assign(ref lhs, _) = parent.kind {
+ return lhs.hir_id == expr.hir_id;
}
}
false
projects / rust.git / blobdiff