Split lint into slow and unsafe vector initalization

clippy_lints/src/slow_vector_initialization.rs

@@ -37,7 +37,25 @@ use crate::rustc_errors::{Applicability};
 declare_clippy_lint! {
     pub SLOW_VECTOR_INITIALIZATION,
     perf,
-    "slow or unsafe vector initialization"
+    "slow vector initialization"
+}
+
+/// **What it does:** Checks unsafe vector initialization
+///
+/// **Why is this bad?** Changing the length of a vector may expose uninitialized memory, which
+/// can lead to memory safety issues
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// let mut vec1 = Vec::with_capacity(len);
+/// unsafe { vec1.set_len(len); }
+/// ```
+declare_clippy_lint! {
+    pub UNSAFE_VECTOR_INITIALIZATION,
+    correctness,
+    "unsafe vector initialization"
 }
 
 #[derive(Copy, Clone, Default)]
@@ -45,7 +63,10 @@ pub struct Pass;
 
 impl LintPass for Pass {
     fn get_lints(&self) -> LintArray {
-        lint_array!(SLOW_VECTOR_INITIALIZATION)
+        lint_array!(
+            SLOW_VECTOR_INITIALIZATION,
+            UNSAFE_VECTOR_INITIALIZATION,
+        )
     }
 }
 
@@ -96,7 +117,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
                     len_expr: len_arg,
                 };
 
-                Pass::search_slow_initialization(cx, vi, expr.id, expr.span);
+                Pass::search_slow_initialization(cx, vi, expr.id);
             }
         }
     }
@@ -117,7 +138,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
                     len_expr: len_arg,
                 };
 
-                Pass::search_slow_initialization(cx, vi, stmt.node.id(), stmt.span);
+                Pass::search_slow_initialization(cx, vi, stmt.node.id());
             }
         }
     }
@@ -145,8 +166,7 @@ impl Pass {
     fn search_slow_initialization<'tcx>(
         cx: &LateContext<'_, 'tcx>,
         vec_initialization: VecInitialization<'tcx>,
-        parent_node: NodeId,
+        parent_node: NodeId
-        parent_span: Span
     ) {
         let enclosing_body = get_enclosing_block(cx, parent_node);
 
@@ -163,30 +183,54 @@ impl Pass {
 
         v.visit_block(enclosing_body.unwrap());
 
-        if let Some(ref repeat_expr) = v.slow_expression {
+        if let Some(ref initialization_expr) = v.slow_expression {
-            span_lint_and_then(
+            let alloc_span = v.vec_ini.initialization_expr.span;
-                cx,
+            Pass::lint_initialization(cx, initialization_expr, alloc_span);
-                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 at");
-                        },
-                        InitializationType::Resize(e) => {
-                            db.span_note(e.span, "resized at");
-                        },
-                        InitializationType::UnsafeSetLen(e) => {
-                            db.span_note(e.span, "changed len at");
-                        },
-                    }
-                }
-            );
         }
     }
+
+    fn lint_initialization<'tcx>(cx: &LateContext<'_, 'tcx>, initialization: &InitializationType<'tcx>, alloc_span: Span) {
+        match initialization {
+            InitializationType::UnsafeSetLen(e) =>
+                Pass::lint_unsafe_initialization(cx, e, alloc_span),
+
+            InitializationType::Extend(e) |
+            InitializationType::Resize(e) =>
+                Pass::lint_slow_initialization(cx, e, alloc_span),
+        };
+    }
+
+    fn lint_slow_initialization<'tcx>(
+        cx: &LateContext<'_, 'tcx>,
+        slow_fill: &Expr,
+        alloc_span: Span,
+    ) {
+        span_lint_and_then(
+            cx,
+            SLOW_VECTOR_INITIALIZATION,
+            slow_fill.span,
+            "detected slow zero-filling initialization",
+            |db| {
+                db.span_suggestion_with_applicability(alloc_span, "consider replacing with", "vec![0; ..]".to_string(), Applicability::Unspecified);
+            }
+        );
+    }
+
+    fn lint_unsafe_initialization<'tcx>(
+        cx: &LateContext<'_, 'tcx>,
+        slow_fill: &Expr,
+        alloc_span: Span,
+    ) {
+        span_lint_and_then(
+            cx,
+            UNSAFE_VECTOR_INITIALIZATION,
+            slow_fill.span,
+            "detected unsafe vector initialization",
+            |db| {
+                db.span_suggestion_with_applicability(alloc_span, "consider replacing with", "vec![0; ..]".to_string(), Applicability::Unspecified);
+            }
+        );
+    }
 }
 
 /// SlowInitializationVisitor searches for slow zero filling vector initialization, for the given

tests/ui/slow_vector_initialization.stderr

@@ -1,115 +1,73 @@
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:22:5
-   |
-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 at
   --> $DIR/slow_vector_initialization.rs:23:5
    |
+22 |     let mut vec1 = Vec::with_capacity(len);
+   |                    ----------------------- help: consider replacing with: `vec![0; ..]`
 23 |     vec1.extend(repeat(0).take(len));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::slow-vector-initialization` implied by `-D warnings`
 
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:26:5
-   |
-26 |     let mut vec2 = Vec::with_capacity(len - 10);
-   |     ^^^^^^^^^^^^^^^----------------------------^
-   |                    |
-   |                    help: consider replacing with: `vec![0; ..]`
-   |
-note: extended at
   --> $DIR/slow_vector_initialization.rs:27:5
    |
+26 |     let mut vec2 = Vec::with_capacity(len - 10);
+   |                    ---------------------------- help: consider replacing with: `vec![0; ..]`
 27 |     vec2.extend(repeat(0).take(len - 10));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:39:5
-   |
-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
    |
+39 |     let mut resized_vec = Vec::with_capacity(30);
+   |                           ---------------------- help: consider replacing with: `vec![0; ..]`
+...
 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 at
   --> $DIR/slow_vector_initialization.rs:44:5
    |
+40 |     let mut extend_vec = Vec::with_capacity(30);
+   |                          ---------------------- help: consider replacing with: `vec![0; ..]`
+...
 44 |     extend_vec.extend(repeat(0).take(30));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:50:5
-   |
-50 |     let mut vec1 = Vec::with_capacity(len);
-   |     ^^^^^^^^^^^^^^^-----------------------^
-   |                    |
-   |                    help: consider replacing with: `vec![0; ..]`
-   |
-note: resized at
   --> $DIR/slow_vector_initialization.rs:51:5
    |
+50 |     let mut vec1 = Vec::with_capacity(len);
+   |                    ----------------------- help: consider replacing with: `vec![0; ..]`
 51 |     vec1.resize(len, 0);
    |     ^^^^^^^^^^^^^^^^^^^
 
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:58:5
-   |
-58 |     let mut vec3 = Vec::with_capacity(len - 10);
-   |     ^^^^^^^^^^^^^^^----------------------------^
-   |                    |
-   |                    help: consider replacing with: `vec![0; ..]`
-   |
-note: resized at
   --> $DIR/slow_vector_initialization.rs:59:5
    |
+58 |     let mut vec3 = Vec::with_capacity(len - 10);
+   |                    ---------------------------- help: consider replacing with: `vec![0; ..]`
 59 |     vec3.resize(len - 10, 0);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: detected slow zero-filling initialization
-  --> $DIR/slow_vector_initialization.rs:62:5
-   |
-62 |     vec1 = Vec::with_capacity(10);
-   |     ^^^^^^^----------------------
-   |            |
-   |            help: consider replacing with: `vec![0; ..]`
-   |
-note: resized at
   --> $DIR/slow_vector_initialization.rs:63:5
    |
+62 |     vec1 = Vec::with_capacity(10);
+   |            ---------------------- help: consider replacing with: `vec![0; ..]`
 63 |     vec1.resize(10, 0);
    |     ^^^^^^^^^^^^^^^^^^
 
-error: detected slow zero-filling initialization
+error: detected unsafe vector 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
    |
+67 |     let mut unsafe_vec: Vec<u8> = Vec::with_capacity(200);
+   |                                   ----------------------- help: consider replacing with: `vec![0; ..]`
+...
 70 |         unsafe_vec.set_len(200);
    |         ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: #[deny(clippy::unsafe_vector_initialization)] on by default
 
 error: aborting due to 8 previous errors