Add test of VEC.push on a const

Author: dtolnay

src/test/ui/lint/lint-const-item-mutation.rs

@@ -28,6 +28,7 @@ const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr:
 const RAW_PTR: *mut u8 = 1 as *mut u8;
 const MUTABLE: Mutable = Mutable { msg: "" };
 const MUTABLE2: Mutable2 = Mutable2 { msg: "", other: String::new() };
+const VEC: Vec<i32> = Vec::new();
 
 fn main() {
     ARRAY[0] = 5; //~ WARN attempting to modify
@@ -48,4 +49,5 @@ fn main() {
 
     MUTABLE.msg = "wow"; // no warning, because Drop observes the mutation
     MUTABLE2.msg = "wow"; //~ WARN attempting to modify
+    VEC.push(0); // no warning
 }

src/test/ui/lint/lint-const-item-mutation.stderr

@@ -1,5 +1,5 @@
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:33:5
+  --> $DIR/lint-const-item-mutation.rs:34:5
    |
 LL |     ARRAY[0] = 5;
    |     ^^^^^^^^^^^^
@@ -13,7 +13,7 @@ LL | const ARRAY: [u8; 1] = [25];
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:34:5
+  --> $DIR/lint-const-item-mutation.rs:35:5
    |
 LL |     MY_STRUCT.field = false;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
@@ -26,7 +26,7 @@ LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:35:5
+  --> $DIR/lint-const-item-mutation.rs:36:5
    |
 LL |     MY_STRUCT.inner_array[0] = 'b';
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -39,7 +39,7 @@ LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:36:5
+  --> $DIR/lint-const-item-mutation.rs:37:5
    |
 LL |     MY_STRUCT.use_mut();
    |     ^^^^^^^^^^^^^^^^^^^
@@ -58,7 +58,7 @@ LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:37:5
+  --> $DIR/lint-const-item-mutation.rs:38:5
    |
 LL |     &mut MY_STRUCT;
    |     ^^^^^^^^^^^^^^
@@ -72,7 +72,7 @@ LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:38:5
+  --> $DIR/lint-const-item-mutation.rs:39:5
    |
 LL |     (&mut MY_STRUCT).use_mut();
    |     ^^^^^^^^^^^^^^^^
@@ -86,7 +86,7 @@ LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:50:5
+  --> $DIR/lint-const-item-mutation.rs:51:5
    |
 LL |     MUTABLE2.msg = "wow";
    |     ^^^^^^^^^^^^^^^^^^^^