-use rustc::hir::def_id::DefId;
-use rustc::hir::intravisit::{Visitor, walk_expr};
+use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc::hir::*;
use rustc::ty;
use rustc::lint::*;
-use utils::{get_parent_expr, span_note_and_lint, span_lint};
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
+use syntax::ast;
+use crate::utils::{get_parent_expr, span_lint, span_note_and_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
/// let a = {x = 1; 1} + x;
/// // Unclear whether a is 1 or 2.
/// ```
-declare_lint! {
+declare_clippy_lint! {
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.
+/// **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.
+/// **Known problems:** Someone might want to use `some_bool || panic!()` as a
+/// shorthand.
///
/// **Example:**
/// ```rust
/// let x = (a, b, c, panic!());
/// // can simply be replaced by `panic!()`
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub DIVERGING_SUB_EXPRESSION,
- Warn,
+ complexity,
"whether an expression contains a diverging sub expression"
}
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone)]
pub struct EvalOrderDependence;
impl LintPass for EvalOrderDependence {
}
}
-impl LateLintPass for EvalOrderDependence {
- fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
+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(None, ref path) = lhs.node {
+ ExprKind::Assign(ref lhs, _) | ExprKind::AssignOp(_, ref lhs, _) => if let ExprKind::Path(ref qpath) = lhs.node {
+ if let QPath::Resolved(_, ref path) = *qpath {
if path.segments.len() == 1 {
- let var = cx.tcx.expect_def(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::Def::Local(var) = cx.tables.qpath_def(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, stmt: &Stmt) {
+ fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
match stmt.node {
- StmtExpr(ref e, _) | StmtSemi(ref e, _) => DivergenceVisitor(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).visit_expr(e);
- }
+ StmtKind::Expr(ref e, _) | StmtKind::Semi(ref e, _) => DivergenceVisitor { cx }.maybe_walk_expr(e),
+ StmtKind::Decl(ref d, _) => if let DeclKind::Local(ref local) = d.node {
+ if let Local {
+ init: Some(ref e), ..
+ } = **local
+ {
+ DivergenceVisitor { cx }.visit_expr(e);
}
},
}
}
}
-struct DivergenceVisitor<'a, 'tcx: 'a>(&'a LateContext<'a, 'tcx>);
+struct DivergenceVisitor<'a, 'tcx: 'a> {
+ cx: &'a LateContext<'a, 'tcx>,
+}
impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
- fn maybe_walk_expr(&mut self, e: &Expr) {
+ fn maybe_walk_expr(&mut self, e: &'tcx Expr) {
match e.node {
- ExprClosure(..) => {},
- ExprMatch(ref e, ref arms, _) => {
+ 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);
}
// make sure top level arm expressions aren't linted
- walk_expr(self, &*arm.body);
+ self.maybe_walk_expr(&*arm.body);
}
- }
+ },
_ => walk_expr(self, e),
}
}
fn report_diverging_sub_expr(&mut self, e: &Expr) {
- span_lint(
- self.0,
- DIVERGING_SUB_EXPRESSION,
- e.span,
- "sub-expression diverges",
- );
+ span_lint(self.cx, DIVERGING_SUB_EXPRESSION, e.span, "sub-expression diverges");
}
}
-impl<'a, 'tcx, 'v> Visitor<'v> for DivergenceVisitor<'a, 'tcx> {
- fn visit_expr(&mut self, e: &'v Expr) {
+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.0.tcx.expr_ty(func).sty {
- ty::TyFnDef(_, _, fn_ty) |
- ty::TyFnPtr(fn_ty) => if let ty::TyNever = self.0.tcx.erase_late_bound_regions(&fn_ty.sig).output.sty {
- self.report_diverging_sub_expr(e);
- },
- _ => {},
+ 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.sty {
+ ty::TyFnDef(..) | ty::TyFnPtr(_) => {
+ let sig = typ.fn_sig(self.cx.tcx);
+ if let ty::TyNever = self.cx.tcx.erase_late_bound_regions(&sig).output().sty {
+ self.report_diverging_sub_expr(e);
+ }
+ },
+ _ => {},
+ }
},
- ExprMethodCall(..) => {
- let method_call = ty::MethodCall::expr(e.id);
- let borrowed_table = self.0.tcx.tables.borrow();
- let method_type = borrowed_table.method_map.get(&method_call).expect("This should never happen.");
- let result_ty = method_type.ty.fn_ret();
- if let ty::TyNever = self.0.tcx.erase_late_bound_regions(&result_ty).sty {
+ 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 to begin with
+ // do not lint expressions referencing objects of type `!`, as that required a
+ // diverging expression
+ // to begin with
},
}
self.maybe_walk_expr(e);
}
- fn visit_block(&mut self, _: &'v Block) {
+ fn visit_block(&mut self, _: &'tcx Block) {
// don't continue over blocks, LateLintPass already does that
}
+ fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ NestedVisitorMap::None
+ }
}
-/// Walks up the AST from the the given write expression (`vis.write_expr`)
-/// looking for reads to the same variable that are unsequenced relative to the
-/// write.
+/// Walks up the AST from the given write expression (`vis.write_expr`) looking
+/// for reads to the same variable that are unsequenced relative to the write.
///
/// This means reads for which there is a common ancestor between the read and
/// the write such that
///
/// When such a read is found, the lint is triggered.
fn check_for_unsequenced_reads(vis: &mut ReadVisitor) {
- let map = &vis.cx.tcx.map;
+ let map = &vis.cx.tcx.hir;
let mut cur_id = vis.write_expr.id;
loop {
let parent_id = map.get_parent_node(cur_id);
// We reached the top of the function, stop.
break;
},
- _ => { StopEarly::KeepGoing }
+ _ => StopEarly::KeepGoing,
};
match stop_early {
StopEarly::Stop => break,
Stop,
}
-fn check_expr<'v, 't>(vis: & mut ReadVisitor<'v, 't>, expr: &'v Expr) -> StopEarly {
+fn check_expr<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, expr: &'tcx Expr) -> StopEarly {
if expr.id == vis.last_expr.id {
return StopEarly::KeepGoing;
}
match expr.node {
- ExprVec(_) |
- ExprTup(_) |
- ExprMethodCall(_, _, _) |
- ExprCall(_, _) |
- ExprAssign(_, _) |
- ExprIndex(_, _) |
- ExprRepeat(_, _) |
- ExprStruct(_, _, _) => {
+ 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
//
// This is also the only place we need to stop early (grrr).
return StopEarly::Stop;
- }
+ },
// All other expressions either have only one child or strictly
// sequence the evaluation order of their sub-expressions.
- _ => {}
+ _ => {},
}
vis.last_expr = expr;
StopEarly::KeepGoing
}
-fn check_stmt<'v, 't>(vis: &mut ReadVisitor<'v, 't>, stmt: &'v Stmt) -> StopEarly {
+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, _) => {
+ StmtKind::Expr(ref expr, _) | StmtKind::Semi(ref expr, _) => check_expr(vis, expr),
+ StmtKind::Decl(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),
+ DeclKind::Local(ref local) => Some(local),
_ => None,
};
- local.and_then(|local| local.init.as_ref())
+ local
+ .and_then(|local| local.init.as_ref())
.map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr))
- }
+ },
}
}
/// A visitor that looks for reads from a variable.
-struct ReadVisitor<'v, 't: 'v> {
- cx: &'v LateContext<'v, 't>,
+struct ReadVisitor<'a, 'tcx: 'a> {
+ cx: &'a LateContext<'a, 'tcx>,
/// The id of the variable we're looking for.
- var: DefId,
+ var: ast::NodeId,
/// The expressions where the write to the variable occurred (for reporting
/// in the lint).
- write_expr: &'v Expr,
+ write_expr: &'tcx Expr,
/// The last (highest in the AST) expression we've checked, so we know not
/// to recheck it.
- last_expr: &'v Expr,
+ last_expr: &'tcx Expr,
}
-impl<'v, 't> Visitor<'v> for ReadVisitor<'v, 't> {
- fn visit_expr(&mut self, expr: &'v 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 {
return;
}
match expr.node {
- ExprPath(None, ref path) => {
- if path.segments.len() == 1 && self.cx.tcx.expect_def(expr.id).def_id() == self.var {
- if is_in_assignment_position(self.cx, expr) {
- // This is a write, not a read.
- } else {
+ ExprKind::Path(ref qpath) => {
+ if_chain! {
+ if let QPath::Resolved(None, ref path) = *qpath;
+ if path.segments.len() == 1;
+ if let def::Def::Local(local_id) = self.cx.tables.qpath_def(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,
// 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;
}
_ => {}
walk_expr(self, expr);
}
+ fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ NestedVisitorMap::None
+ }
}
/// 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 {
+ if let ExprKind::Assign(ref lhs, _) = parent.node {
return lhs.id == expr.id;
}
}
projects / rust.git / blobdiff