add more test cases

Author: y21

tests/ui/missing_asserts_for_indexing.fixed

@@ -107,4 +107,17 @@ fn index_different_slices_one_wrong_len(v1: &[u8], v2: &[u8]) {
     let _ = v2[5] + v2[15];
 }
 
+fn side_effect() -> &'static [u8] {
+    &[]
+}
+
+fn index_side_effect_expr() {
+    let _ = side_effect()[0] + side_effect()[1];
+}
+
+// ok, single access for different slices
+fn index_different_slice_in_same_expr(v1: &[u8], v2: &[u8]) {
+    let _ = v1[0] + v2[1];
+}
+
 fn main() {}

tests/ui/missing_asserts_for_indexing.rs

@@ -107,4 +107,17 @@ fn index_different_slices_one_wrong_len(v1: &[u8], v2: &[u8]) {
     let _ = v2[5] + v2[15];
 }
 
+fn side_effect() -> &'static [u8] {
+    &[]
+}
+
+fn index_side_effect_expr() {
+    let _ = side_effect()[0] + side_effect()[1];
+}
+
+// ok, single access for different slices
+fn index_different_slice_in_same_expr(v1: &[u8], v2: &[u8]) {
+    let _ = v1[0] + v2[1];
+}
+
 fn main() {}

tests/ui/missing_asserts_for_indexing_unfixable.rs

@@ -31,4 +31,13 @@ fn index_different_slices2(v1: &[u8], v2: &[u8]) {
     let _ = v2[5] + v2[15];
 }
 
+struct Foo<'a> {
+    v: &'a [u8],
+}
+
+fn index_struct_field(f: &Foo<'_>) {
+    //~^ ERROR missing assertion on `f.v.len()`
+    let _ = f.v[0] + f.v[1];
+}
+
 fn main() {}

tests/ui/missing_asserts_for_indexing_unfixable.stderr

@@ -138,5 +138,24 @@ LL |     let _ = v2[5] + v2[15];
    |                     ^^^^^^
    = note: asserting the length before indexing will elide bounds checks
 
-error: aborting due to 6 previous errors
+error: indexing into a slice multiple times without an `assert`
+  --> $DIR/missing_asserts_for_indexing_unfixable.rs:40:13
+   |
+LL |     let _ = f.v[0] + f.v[1];
+   |             ^^^^^^^^^^^^^^^
+   |
+   = help: consider asserting the length before indexing: `assert!(f.v.len() > 1);`
+note: slice indexed here
+  --> $DIR/missing_asserts_for_indexing_unfixable.rs:40:13
+   |
+LL |     let _ = f.v[0] + f.v[1];
+   |             ^^^^^^
+note: slice indexed here
+  --> $DIR/missing_asserts_for_indexing_unfixable.rs:40:22
+   |
+LL |     let _ = f.v[0] + f.v[1];
+   |                      ^^^^^^
+   = note: asserting the length before indexing will elide bounds checks
+
+error: aborting due to 7 previous errors