-// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use crate::rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use crate::rustc::{declare_tool_lint, lint_array};
-use crate::rustc::hir::*;
+use crate::utils::sugg::Sugg;
+use crate::utils::{get_enclosing_block, match_qpath, span_lint_and_then, SpanlessEq};
use if_chain::if_chain;
-use crate::syntax_pos::symbol::Symbol;
-use crate::syntax::ast::{LitKind, NodeId};
-use crate::syntax::source_map::Span;
-use crate::utils::{match_qpath, span_lint_and_then, SpanlessEq};
-use crate::utils::get_enclosing_block;
-use crate::rustc_errors::{Applicability};
-
-/// **What it does:** Checks slow zero-filled vector initialization
-///
-/// **Why is this bad?** This structures are non-idiomatic and less efficient than simply using
-/// `vec![len; 0]`.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// let mut vec1 = Vec::with_capacity(len);
-/// vec1.resize(len, 0);
-///
-/// let mut vec2 = Vec::with_capacity(len);
-/// vec2.extend(repeat(0).take(len))
-/// ```
+use rustc::hir::intravisit::{walk_block, walk_expr, walk_stmt, NestedVisitorMap, Visitor};
+use rustc::hir::*;
+use rustc::lint::{LateContext, LateLintPass, Lint, LintArray, LintPass};
+use rustc::{declare_lint_pass, declare_tool_lint};
+use rustc_errors::Applicability;
+use syntax::ast::LitKind;
+use syntax_pos::symbol::Symbol;
+
declare_clippy_lint! {
+ /// **What it does:** Checks slow zero-filled vector initialization
+ ///
+ /// **Why is this bad?** These structures are non-idiomatic and less efficient than simply using
+ /// `vec![0; len]`.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// # use core::iter::repeat;
+ /// # let len = 4;
+ /// let mut vec1 = Vec::with_capacity(len);
+ /// vec1.resize(len, 0);
+ ///
+ /// let mut vec2 = Vec::with_capacity(len);
+ /// vec2.extend(repeat(0).take(len))
+ /// ```
pub SLOW_VECTOR_INITIALIZATION,
perf,
- "slow or unsafe vector initialization"
+ "slow vector initialization"
}
-#[derive(Copy, Clone, Default)]
-pub struct Pass;
-
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array!(SLOW_VECTOR_INITIALIZATION)
- }
-}
+declare_lint_pass!(SlowVectorInit => [SLOW_VECTOR_INITIALIZATION]);
-/// VecInitialization contains data regarding a vector initialized with `with_capacity` and then
+/// `VecAllocation` contains data regarding a vector allocated with `with_capacity` and then
/// assigned to a variable. For example, `let mut vec = Vec::with_capacity(0)` or
/// `vec = Vec::with_capacity(0)`
-struct VecInitialization<'tcx> {
+struct VecAllocation<'tcx> {
/// Symbol of the local variable name
variable_name: Symbol,
- /// Reference to the expression which initializes the vector
- initialization_expr: &'tcx Expr,
+ /// Reference to the expression which allocates the vector
+ allocation_expr: &'tcx Expr,
/// Reference to the expression used as argument on `with_capacity` call. This is used
/// to only match slow zero-filling idioms of the same length than vector initialization.
Resize(&'tcx Expr),
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for SlowVectorInit {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
// Matches initialization on reassignements. For example: `vec = Vec::with_capacity(100)`
if_chain! {
if let Some(variable_name) = path.segments.get(0);
// Extract len argument
- if let Some(ref len_arg) = Pass::is_vec_with_capacity(right);
+ if let Some(ref len_arg) = Self::is_vec_with_capacity(right);
then {
- let vi = VecInitialization {
+ let vi = VecAllocation {
variable_name: variable_name.ident.name,
- initialization_expr: right,
+ allocation_expr: right,
len_expr: len_arg,
};
- Pass::search_slow_zero_filling(cx, vi, expr.id, expr.span);
+ Self::search_initialization(cx, vi, expr.hir_id);
}
}
}
fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
// Matches statements which initializes vectors. For example: `let mut vec = Vec::with_capacity(10)`
if_chain! {
- if let StmtKind::Decl(ref decl, _) = stmt.node;
- if let DeclKind::Local(ref local) = decl.node;
- if let PatKind::Binding(BindingAnnotation::Mutable, _, variable_name, None) = local.pat.node;
+ if let StmtKind::Local(ref local) = stmt.node;
+ if let PatKind::Binding(BindingAnnotation::Mutable, .., variable_name, None) = local.pat.node;
if let Some(ref init) = local.init;
- if let Some(ref len_arg) = Pass::is_vec_with_capacity(init);
+ if let Some(ref len_arg) = Self::is_vec_with_capacity(init);
then {
- let vi = VecInitialization {
+ let vi = VecAllocation {
variable_name: variable_name.name,
- initialization_expr: init,
+ allocation_expr: init,
len_expr: len_arg,
};
- Pass::search_slow_zero_filling(cx, vi, stmt.node.id(), stmt.span);
+ Self::search_initialization(cx, vi, stmt.hir_id);
}
}
}
}
-impl Pass {
+impl SlowVectorInit {
/// Checks if the given expression is `Vec::with_capacity(..)`. It will return the expression
/// of the first argument of `with_capacity` call if it matches or `None` if it does not.
fn is_vec_with_capacity(expr: &Expr) -> Option<&Expr> {
None
}
- /// Search for slow zero filling vector initialization for the given vector
- fn search_slow_zero_filling<'tcx>(
- cx: &LateContext<'_, 'tcx>,
- vec_initialization: VecInitialization<'tcx>,
- parent_node: NodeId,
- parent_span: Span
- ) {
+ /// Search initialization for the given vector
+ fn search_initialization<'tcx>(cx: &LateContext<'_, 'tcx>, vec_alloc: VecAllocation<'tcx>, parent_node: HirId) {
let enclosing_body = get_enclosing_block(cx, parent_node);
if enclosing_body.is_none() {
return;
}
- let mut v = SlowInitializationVisitor {
+ let mut v = VectorInitializationVisitor {
cx,
- vec_ini: vec_initialization,
+ vec_alloc,
slow_expression: None,
initialization_found: false,
};
v.visit_block(enclosing_body.unwrap());
- if let Some(ref repeat_expr) = v.slow_expression {
- span_lint_and_then(
+ if let Some(ref allocation_expr) = v.slow_expression {
+ Self::lint_initialization(cx, allocation_expr, &v.vec_alloc);
+ }
+ }
+
+ fn lint_initialization<'tcx>(
+ cx: &LateContext<'_, 'tcx>,
+ initialization: &InitializationType<'tcx>,
+ vec_alloc: &VecAllocation<'_>,
+ ) {
+ match initialization {
+ InitializationType::Extend(e) | InitializationType::Resize(e) => Self::emit_lint(
cx,
+ e,
+ vec_alloc,
+ "slow zero-filling initialization",
SLOW_VECTOR_INITIALIZATION,
- parent_span,
- "detected slow zero-filling initialization",
- |db| {
- db.span_suggestion_with_applicability(v.vec_ini.initialization_expr.span, "consider replacing with", "vec![0; ..]".to_string(), Applicability::Unspecified);
-
- match repeat_expr {
- InitializationType::Extend(e) => {
- db.span_note(e.span, "extended here with .. 0");
- },
- InitializationType::Resize(e) => {
- db.span_note(e.span, "resize here with .. 0");
- }
- }
- }
+ ),
+ };
+ }
+
+ fn emit_lint<'tcx>(
+ cx: &LateContext<'_, 'tcx>,
+ slow_fill: &Expr,
+ vec_alloc: &VecAllocation<'_>,
+ msg: &str,
+ lint: &'static Lint,
+ ) {
+ let len_expr = Sugg::hir(cx, vec_alloc.len_expr, "len");
+
+ span_lint_and_then(cx, lint, slow_fill.span, msg, |db| {
+ db.span_suggestion(
+ vec_alloc.allocation_expr.span,
+ "consider replace allocation with",
+ format!("vec![0; {}]", len_expr),
+ Applicability::Unspecified,
);
- }
+ });
}
}
-/// SlowInitializationVisitor searches for slow zero filling vector initialization, for the given
+/// `VectorInitializationVisitor` searches for unsafe or slow vector initializations for the given
/// vector.
-struct SlowInitializationVisitor<'a, 'tcx: 'a> {
+struct VectorInitializationVisitor<'a, 'tcx> {
cx: &'a LateContext<'a, 'tcx>,
- /// Contains the information
- vec_ini: VecInitialization<'tcx>,
+ /// Contains the information.
+ vec_alloc: VecAllocation<'tcx>,
- /// Contains, if found, the slow initialization expression
+ /// Contains the slow initialization expression, if one was found.
slow_expression: Option<InitializationType<'tcx>>,
- /// true if the initialization of the vector has been found on the visited block
+ /// `true` if the initialization of the vector has been found on the visited block.
initialization_found: bool,
}
-impl<'a, 'tcx> SlowInitializationVisitor<'a, 'tcx> {
+impl<'a, 'tcx> VectorInitializationVisitor<'a, 'tcx> {
/// Checks if the given expression is extending a vector with `repeat(0).take(..)`
fn search_slow_extend_filling(&mut self, expr: &'tcx Expr) {
if_chain! {
if self.initialization_found;
if let ExprKind::MethodCall(ref path, _, ref args) = expr.node;
if let ExprKind::Path(ref qpath_subj) = args[0].node;
- if match_qpath(&qpath_subj, &[&self.vec_ini.variable_name.to_string()]);
- if path.ident.name == "extend";
+ if match_qpath(&qpath_subj, &[&*self.vec_alloc.variable_name.as_str()]);
+ if path.ident.name == sym!(extend);
if let Some(ref extend_arg) = args.get(1);
if self.is_repeat_take(extend_arg);
if self.initialization_found;
if let ExprKind::MethodCall(ref path, _, ref args) = expr.node;
if let ExprKind::Path(ref qpath_subj) = args[0].node;
- if match_qpath(&qpath_subj, &[&self.vec_ini.variable_name.to_string()]);
- if path.ident.name == "resize";
+ if match_qpath(&qpath_subj, &[&*self.vec_alloc.variable_name.as_str()]);
+ if path.ident.name == sym!(resize);
if let (Some(ref len_arg), Some(fill_arg)) = (args.get(1), args.get(2));
// Check that is filled with 0
if let LitKind::Int(0, _) = lit.node;
// Check that len expression is equals to `with_capacity` expression
- if SpanlessEq::new(self.cx).eq_expr(len_arg, self.vec_ini.len_expr);
+ if SpanlessEq::new(self.cx).eq_expr(len_arg, self.vec_alloc.len_expr);
then {
self.slow_expression = Some(InitializationType::Resize(expr));
fn is_repeat_take(&self, expr: &Expr) -> bool {
if_chain! {
if let ExprKind::MethodCall(ref take_path, _, ref take_args) = expr.node;
- if take_path.ident.name == "take";
+ if take_path.ident.name == sym!(take);
// Check that take is applied to `repeat(0)`
if let Some(ref repeat_expr) = take_args.get(0);
// Check that len expression is equals to `with_capacity` expression
if let Some(ref len_arg) = take_args.get(1);
- if SpanlessEq::new(self.cx).eq_expr(len_arg, self.vec_ini.len_expr);
+ if SpanlessEq::new(self.cx).eq_expr(len_arg, self.vec_alloc.len_expr);
then {
return true;
}
}
-impl<'a, 'tcx> Visitor<'tcx> for SlowInitializationVisitor<'a, 'tcx> {
- fn visit_expr(&mut self, expr: &'tcx Expr) {
- // Stop the search if we already found a slow zero-filling initialization
- if self.slow_expression.is_some() {
- return
+impl<'a, 'tcx> Visitor<'tcx> for VectorInitializationVisitor<'a, 'tcx> {
+ fn visit_stmt(&mut self, stmt: &'tcx Stmt) {
+ if self.initialization_found {
+ match stmt.node {
+ StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => {
+ self.search_slow_extend_filling(expr);
+ self.search_slow_resize_filling(expr);
+ },
+ _ => (),
+ }
+
+ self.initialization_found = false;
+ } else {
+ walk_stmt(self, stmt);
}
+ }
+ fn visit_block(&mut self, block: &'tcx Block) {
+ if self.initialization_found {
+ if let Some(ref s) = block.stmts.get(0) {
+ self.visit_stmt(s)
+ }
+
+ self.initialization_found = false;
+ } else {
+ walk_block(self, block);
+ }
+ }
+
+ fn visit_expr(&mut self, expr: &'tcx Expr) {
// Skip all the expressions previous to the vector initialization
- if self.vec_ini.initialization_expr.id == expr.id {
+ if self.vec_alloc.allocation_expr.hir_id == expr.hir_id {
self.initialization_found = true;
}
-
- self.search_slow_extend_filling(expr);
- self.search_slow_resize_filling(expr);
walk_expr(self, expr);
}
projects / rust.git / blobdiff