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simplify looking for Vec::with_capacity exprs

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y21 2023-07-25 18:56:57 +02:00
parent 1fe2762900
commit c0484b74f7
2 changed files with 10 additions and 19 deletions
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28
clippy_lints/src/slow_vector_initialization.rs
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@ -1,6 +1,5 @@
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{
get_enclosing_block, is_expr_path_def_path, is_integer_literal, is_path_diagnostic_item, path_to_local,
path_to_local_id, paths, SpanlessEq,
@ -8,7 +7,7 @@ use clippy_utils::{
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::{walk_block, walk_expr, walk_stmt, Visitor};
use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, PatKind, QPath, Stmt, StmtKind};
use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, PatKind, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::sym;
@ -133,8 +132,15 @@ impl<'tcx> LateLintPass<'tcx> for SlowVectorInit {
}
impl SlowVectorInit {
/// Looks for `Vec::with_capacity(size)` or `Vec::new()` calls and returns the initialized size,
/// if any. More specifically, it returns:
/// - `Some(InitializedSize::Initialized(size))` for `Vec::with_capacity(size)`
/// - `Some(InitializedSize::Uninitialized)` for `Vec::new()`
/// - `None` for other, unrelated kinds of expressions
fn as_vec_initializer<'tcx>(cx: &LateContext<'_>, expr: &'tcx Expr<'tcx>) -> Option<InitializedSize<'tcx>> {
if let Some(len_expr) = Self::is_vec_with_capacity(cx, expr) {
if let ExprKind::Call(func, [len_expr]) = expr.kind
&& is_expr_path_def_path(cx, func, &paths::VEC_WITH_CAPACITY)
{
Some(InitializedSize::Initialized(len_expr))
} else if matches!(expr.kind, ExprKind::Call(func, _) if is_expr_path_def_path(cx, func, &paths::VEC_NEW)) {
Some(InitializedSize::Uninitialized)
@ -143,22 +149,6 @@ 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<'tcx>(cx: &LateContext<'_>, expr: &Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
if_chain! {
if let ExprKind::Call(func, [arg]) = expr.kind;
if let ExprKind::Path(QPath::TypeRelative(ty, name)) = func.kind;
if name.ident.as_str() == "with_capacity";
if is_type_diagnostic_item(cx, cx.typeck_results().node_type(ty.hir_id), sym::Vec);
then {
Some(arg)
} else {
None
}
}
}
/// 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);

1
clippy_utils/src/paths.rs
View File

@ -149,6 +149,7 @@ pub const VEC_AS_SLICE: [&str; 4] = ["alloc", "vec", "Vec", "as_slice"];
pub const VEC_DEQUE_ITER: [&str; 5] = ["alloc", "collections", "vec_deque", "VecDeque", "iter"];
pub const VEC_FROM_ELEM: [&str; 3] = ["alloc", "vec", "from_elem"];
pub const VEC_NEW: [&str; 4] = ["alloc", "vec", "Vec", "new"];
pub const VEC_WITH_CAPACITY: [&str; 4] = ["alloc", "vec", "Vec", "with_capacity"];
pub const VEC_RESIZE: [&str; 4] = ["alloc", "vec", "Vec", "resize"];
pub const WEAK_ARC: [&str; 3] = ["alloc", "sync", "Weak"];
pub const WEAK_RC: [&str; 3] = ["alloc", "rc", "Weak"];