adjust for missing spans on x86 test runner

Author: RalfJung

src/test/ui/consts/offset_from_ub.rs

@@ -1,5 +1,4 @@
-// ingoring on musl because it's ui output hides libcore backtraces
-// ignore-musl
+// ignore-x86 FIXME: missing sysroot spans (#53081)
 
 #![feature(const_raw_ptr_deref)]
 #![feature(const_ptr_offset_from)]

src/test/ui/consts/offset_from_ub.stderr

@@ -5,9 +5,9 @@ LL |           intrinsics::ptr_offset_from(self, origin)
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |           |
    |           ptr_offset_from cannot compute offset of pointers into different allocations.
-   |           inside call to `std::ptr::<impl *const Struct>::offset_from` at $DIR/offset_from_ub.rs:20:27
+   |           inside call to `std::ptr::<impl *const Struct>::offset_from` at $DIR/offset_from_ub.rs:19:27
    | 
-  ::: $DIR/offset_from_ub.rs:14:1
+  ::: $DIR/offset_from_ub.rs:13:1
    |
 LL | / pub const DIFFERENT_ALLOC: usize = {
 LL | |
@@ -27,9 +27,9 @@ LL |           intrinsics::ptr_offset_from(self, origin)
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |           |
    |           a memory access tried to interpret some bytes as a pointer
-   |           inside call to `std::ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:26:14
+   |           inside call to `std::ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:25:14
    | 
-  ::: $DIR/offset_from_ub.rs:24:1
+  ::: $DIR/offset_from_ub.rs:23:1
    |
 LL | / pub const NOT_PTR: usize = {
 LL | |
@@ -44,9 +44,9 @@ LL |           intrinsics::ptr_offset_from(self, origin)
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |           |
    |           exact_div: 1 cannot be divided by 2 without remainder
-   |           inside call to `std::ptr::<impl *const u16>::offset_from` at $DIR/offset_from_ub.rs:34:27
+   |           inside call to `std::ptr::<impl *const u16>::offset_from` at $DIR/offset_from_ub.rs:33:27
    | 
-  ::: $DIR/offset_from_ub.rs:29:1
+  ::: $DIR/offset_from_ub.rs:28:1
    |
 LL | / pub const NOT_MULTIPLE_OF_SIZE: usize = {
 LL | |