Rollup merge of #51308 - fanzier:const-prop-array-bounds-check, r=oli-obk

Check array indices in constant propagation

Previously, uses of constant weren't correctly propagated.
This fixes #48920.

r? @oli-obk because you suggested it

src/test/ui/const-eval/index_out_of_bound.stderr

@@ -1,9 +0,0 @@
-error[E0080]: constant evaluation error
-  --> $DIR/index_out_of_bound.rs:11:19
-   |
-LL | static FOO: i32 = [][0];
-   |                   ^^^^^ index out of bounds: the len is 0 but the index is 0
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0080`.

src/test/ui/const-eval/index_out_of_bounds.rs

@@ -11,4 +11,7 @@
 static FOO: i32 = [][0];
 //~^ ERROR E0080
 
-fn main() {}
+fn main() {
+    let array = [std::env::args().len()];
+    array[1]; //~ ERROR index out of bounds
+}

src/test/ui/const-eval/index_out_of_bounds.stderr

@@ -0,0 +1,17 @@
+error[E0080]: constant evaluation error
+  --> $DIR/index_out_of_bounds.rs:11:19
+   |
+LL | static FOO: i32 = [][0];
+   |                   ^^^^^ index out of bounds: the len is 0 but the index is 0
+
+error: index out of bounds: the len is 1 but the index is 1
+  --> $DIR/index_out_of_bounds.rs:16:5
+   |
+LL |     array[1]; //~ ERROR index out of bounds
+   |     ^^^^^^^^
+   |
+   = note: #[deny(const_err)] on by default
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0080`.