Support debuginfo for custom MIR.

[cjgillot]

No description provided.

[rustbot]

r? @petrochenkov

(rustbot has picked a reviewer for you, use r? to override)

[petrochenkov]

r? compiler

[oli-obk]

@bors r+ rollup

[bors]

📌 Commit 905fd1b has been approved by oli-obk

It is now in the queue for this repository.

[RalfJung]

Did this break stage 0 Miri tests? ./x.py test miri --stage 0

tests/pass/function_calls/return_place_on_heap.rs FAILED:
command: "/home/r/src/rust/rustc/build/x86_64-unknown-linux-gnu/stage0-tools-bin/miri" "--error-format=json" "-Dwarnings" "-Dunused" "-Ainternal_features" "-Zui-testing" "--target" "x86_64-unknown-linux-gnu" "--out-dir" "/home/r/src/rust/rustc/build/x86_64-unknown-linux-gnu/stage0-tools/ui" "tests/pass/function_calls/return_place_on_heap.rs" "--edition" "2021"




pass test got exit status: 1, but expected 0

actual output differed from expected
Execute `./miri test --bless` to update `tests/pass/function_calls/return_place_on_heap.stderr` to the actual output
--- tests/pass/function_calls/return_place_on_heap.stderr
+++ <stderr output>
+error: Could not parse debuginfo, found: "Block { block: b0 }"
+  --> $DIR/return_place_on_heap.rs:LL:CC
+   |
+LL | /     mir! {
+LL | |         {
+LL | |             let x = 0;
+LL | |             let ptr = &raw mut x;
+...  |
+LL | |         }
+LL | |     }
+   | |_____^
+   |
+   = note: this error originates in the macro `::core::intrinsics::mir::__internal_remove_let` which comes from the expansion of the macro `mir` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+


There were 1 unmatched diagnostics at tests/pass/function_calls/return_place_on_heap.rs:10
    Error: Could not parse debuginfo, found: "Block { block: b0 }"

full stderr:
error: Could not parse debuginfo, found: "Block { block: b0 }"
  --> tests/pass/function_calls/return_place_on_heap.rs:10:5
   |
LL | /     mir! {
LL | |         {
LL | |             let x = 0;
LL | |             let ptr = &raw mut x;
...  |
LL | |         }
LL | |     }
   | |_____^
   |
   = note: this error originates in the macro `::core::intrinsics::mir::__internal_remove_let` which comes from the expansion of the macro `mir` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error



FAILURES:
    tests/pass/align_repeat_into_packed_field.rs
    tests/pass/unsized.rs (revision stack)
    tests/pass/unsized.rs (revision tree)
    tests/pass/function_calls/return_place_on_heap.rs

On CI we only run stage 2 tests, but for local development stage 0 tests are very valuable.

[RalfJung]

Would be great if some doc comment somewhere explained this syntax.