Rollup merge of #103464 - JakobDegen:mir-parsing, r=oli-obk

Add support for custom mir This implements rust-lang/compiler-team#564 . Details about the design, motivation, etc. can be found in there. r? ```@oli-obk```
2022-11-09 15:39:03 -05:00 · 2022-11-09 15:39:03 -05:00 · 3f11d39eec
commit 3f11d39eec
parent 46bc12c95a ba359d8a51
23 changed files with 920 additions and 40 deletions
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@ -584,6 +584,7 @@ symbols! {
        custom_attribute,
        custom_derive,
        custom_inner_attributes,
+        custom_mir,
        custom_test_frameworks,
        d,
        d32,