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Add unsafe set_len initialization

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This commit is contained in:
Guillem Nieto 2018-10-26 22:35:16 +02:00 committed by Guillem Nieto
parent e0ccc9d9af
commit 9b4bc3b6ef
3 changed files with 100 additions and 51 deletions
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40
clippy_lints/src/slow_vector_initialization.rs
View File

@ -71,6 +71,9 @@ enum InitializationType<'tcx> {
/// Resize is a slow initialization with the form `vec.resize(.., 0)`
Resize(&'tcx Expr),
/// UnsafeSetLen is a slow initialization with the form `vec.set_len(..)`
UnsafeSetLen(&'tcx Expr),
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
@ -93,7 +96,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
len_expr: len_arg,
};
Pass::search_slow_zero_filling(cx, vi, expr.id, expr.span);
Pass::search_slow_initialization(cx, vi, expr.id, expr.span);
}
}
}
@ -114,7 +117,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
len_expr: len_arg,
};
Pass::search_slow_zero_filling(cx, vi, stmt.node.id(), stmt.span);
Pass::search_slow_initialization(cx, vi, stmt.node.id(), stmt.span);
}
}
}
@ -138,8 +141,8 @@ impl Pass {
None
}
/// Search for slow zero filling vector initialization for the given vector
fn search_slow_zero_filling<'tcx>(
/// Search a slow initialization for the given vector
fn search_slow_initialization<'tcx>(
cx: &LateContext<'_, 'tcx>,
vec_initialization: VecInitialization<'tcx>,
parent_node: NodeId,
@ -171,11 +174,14 @@ impl Pass {
match repeat_expr {
InitializationType::Extend(e) => {
db.span_note(e.span, "extended here with .. 0");
db.span_note(e.span, "extended at");
},
InitializationType::Resize(e) => {
db.span_note(e.span, "resize here with .. 0");
}
db.span_note(e.span, "resized at");
},
InitializationType::UnsafeSetLen(e) => {
db.span_note(e.span, "changed len at");
},
}
}
);
@ -239,6 +245,25 @@ impl<'a, 'tcx> SlowInitializationVisitor<'a, 'tcx> {
}
}
/// Checks if the given expression is using `set_len` to initialize the vector
fn search_unsafe_set_len(&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 == "set_len";
if let Some(ref len_arg) = args.get(1);
// Check that len expression is equals to `with_capacity` expression
if SpanlessEq::new(self.cx).eq_expr(len_arg, self.vec_ini.len_expr);
then {
self.slow_expression = Some(InitializationType::UnsafeSetLen(expr));
}
}
}
/// Returns `true` if give expression is `repeat(0).take(...)`
fn is_repeat_take(&self, expr: &Expr) -> bool {
if_chain! {
@ -294,6 +319,7 @@ impl<'a, 'tcx> Visitor<'tcx> for SlowInitializationVisitor<'a, 'tcx> {
self.search_slow_extend_filling(expr);
self.search_slow_resize_filling(expr);
self.search_unsafe_set_len(expr);
walk_expr(self, expr);
}

9
tests/ui/slow_vector_initialization.rs
View File

@ -13,6 +13,7 @@ fn main() {
resize_vector();
extend_vector();
mixed_extend_resize_vector();
unsafe_vector();
}
fn extend_vector() {
@ -61,3 +62,11 @@ fn resize_vector() {
vec1 = Vec::with_capacity(10);
vec1.resize(10, 0);
}
fn unsafe_vector() {
let mut unsafe_vec: Vec<u8> = Vec::with_capacity(200);
unsafe {
unsafe_vec.set_len(200);
}
}

102
tests/ui/slow_vector_initialization.stderr
View File

@ -1,101 +1,115 @@
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:21:5
--> $DIR/slow_vector_initialization.rs:22:5
|
21 | let mut vec1 = Vec::with_capacity(len);
22 | let mut vec1 = Vec::with_capacity(len);
| ^^^^^^^^^^^^^^^-----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
= note: `-D clippy::slow-vector-initialization` implied by `-D warnings`
note: extended here with .. 0
--> $DIR/slow_vector_initialization.rs:22:5
note: extended at
--> $DIR/slow_vector_initialization.rs:23:5
|
22 | vec1.extend(repeat(0).take(len));
23 | vec1.extend(repeat(0).take(len));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:25:5
--> $DIR/slow_vector_initialization.rs:26:5
|
25 | let mut vec2 = Vec::with_capacity(len - 10);
26 | let mut vec2 = Vec::with_capacity(len - 10);
| ^^^^^^^^^^^^^^^----------------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: extended here with .. 0
--> $DIR/slow_vector_initialization.rs:26:5
note: extended at
--> $DIR/slow_vector_initialization.rs:27:5
|
26 | vec2.extend(repeat(0).take(len - 10));
27 | vec2.extend(repeat(0).take(len - 10));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:38:5
|
38 | let mut resized_vec = Vec::with_capacity(30);
| ^^^^^^^^^^^^^^^^^^^^^^----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: resize here with .. 0
--> $DIR/slow_vector_initialization.rs:41:5
|
41 | resized_vec.resize(30, 0);
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:39:5
|
39 | let mut extend_vec = Vec::with_capacity(30);
39 | let mut resized_vec = Vec::with_capacity(30);
| ^^^^^^^^^^^^^^^^^^^^^^----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: resized at
--> $DIR/slow_vector_initialization.rs:42:5
|
42 | resized_vec.resize(30, 0);
| ^^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:40:5
|
40 | let mut extend_vec = Vec::with_capacity(30);
| ^^^^^^^^^^^^^^^^^^^^^----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: extended here with .. 0
--> $DIR/slow_vector_initialization.rs:43:5
note: extended at
--> $DIR/slow_vector_initialization.rs:44:5
|
43 | extend_vec.extend(repeat(0).take(30));
44 | extend_vec.extend(repeat(0).take(30));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:49:5
--> $DIR/slow_vector_initialization.rs:50:5
|
49 | let mut vec1 = Vec::with_capacity(len);
50 | let mut vec1 = Vec::with_capacity(len);
| ^^^^^^^^^^^^^^^-----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: resize here with .. 0
--> $DIR/slow_vector_initialization.rs:50:5
note: resized at
--> $DIR/slow_vector_initialization.rs:51:5
|
50 | vec1.resize(len, 0);
51 | vec1.resize(len, 0);
| ^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:57:5
--> $DIR/slow_vector_initialization.rs:58:5
|
57 | let mut vec3 = Vec::with_capacity(len - 10);
58 | let mut vec3 = Vec::with_capacity(len - 10);
| ^^^^^^^^^^^^^^^----------------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: resize here with .. 0
--> $DIR/slow_vector_initialization.rs:58:5
note: resized at
--> $DIR/slow_vector_initialization.rs:59:5
|
58 | vec3.resize(len - 10, 0);
59 | vec3.resize(len - 10, 0);
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:61:5
--> $DIR/slow_vector_initialization.rs:62:5
|
61 | vec1 = Vec::with_capacity(10);
62 | vec1 = Vec::with_capacity(10);
| ^^^^^^^----------------------
| |
| help: consider replacing with: `vec![0; ..]`
|
note: resize here with .. 0
--> $DIR/slow_vector_initialization.rs:62:5
note: resized at
--> $DIR/slow_vector_initialization.rs:63:5
|
62 | vec1.resize(10, 0);
63 | vec1.resize(10, 0);
| ^^^^^^^^^^^^^^^^^^
error: aborting due to 7 previous errors
error: detected slow zero-filling initialization
--> $DIR/slow_vector_initialization.rs:67:5
|
67 | let mut unsafe_vec: Vec<u8> = Vec::with_capacity(200);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-----------------------^
| |
| help: consider replacing with: `vec![0; ..]`
|
note: changed len at
--> $DIR/slow_vector_initialization.rs:70:9
|
70 | unsafe_vec.set_len(200);
| ^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 8 previous errors