Update documentation

Author: oli-obk

compiler/rustc_middle/src/query/mod.rs

@@ -485,12 +485,13 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    /// Fetch the MIR for a given `DefId` up till the point where it is
-    /// ready for const qualification.
+    /// Build the MIR for a given `DefId` and prepare it for const qualification.
     ///
-    /// See the README for the `mir` module for details.
+    /// See the [rustc dev guide] for more info.
+    ///
+    /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/construction.html
     query mir_built(key: LocalDefId) -> &'tcx Steal<mir::Body<'tcx>> {
-        desc { |tcx| "preparing `{}` for borrow checking", tcx.def_path_str(key) }
+        desc { |tcx| "building MIR for `{}`", tcx.def_path_str(key) }
     }
 
     /// Try to build an abstract representation of the given constant.

compiler/rustc_mir_transform/src/lib.rs

@@ -279,9 +279,6 @@ fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs {
     validator.qualifs_in_return_place()
 }
 
-/// Make MIR ready for const evaluation. This is run on all MIR, not just on consts!
-/// FIXME(oli-obk): it's unclear whether we still need this phase (and its corresponding query).
-/// We used to have this for pre-miri MIR based const eval.
 fn mir_built(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> {
     // MIR unsafety check uses the raw mir, so make sure it is run.
     if !tcx.sess.opts.unstable_opts.thir_unsafeck {

tests/ui/coroutine/clone-rpit.next.stderr

@@ -19,7 +19,7 @@ note: ...which requires checking if `foo::{closure#0}` contains FFI-unwind calls
    |
 LL |     move |_: ()| {
    |     ^^^^^^^^^^^^
-note: ...which requires preparing `foo::{closure#0}` for borrow checking...
+note: ...which requires building MIR for `foo::{closure#0}`...
   --> $DIR/clone-rpit.rs:14:5
    |
 LL |     move |_: ()| {

tests/ui/resolve/multiple_definitions_attribute_merging.stderr

@@ -18,7 +18,7 @@ LL | struct Dealigned<T>(u8, T);
    |
    = Box<dyn Any>
 query stack during panic:
-#0 [mir_built] preparing `<impl at $DIR/multiple_definitions_attribute_merging.rs:15:10: 15:19>::eq` for borrow checking
+#0 [mir_built] building MIR for `<impl at $DIR/multiple_definitions_attribute_merging.rs:15:10: 15:19>::eq`
 #1 [check_unsafety] unsafety-checking `<impl at $DIR/multiple_definitions_attribute_merging.rs:15:10: 15:19>::eq`
 end of query stack
 error: aborting due to 2 previous errors

tests/ui/resolve/proc_macro_generated_packed.stderr

@@ -9,7 +9,7 @@ LL | struct Dealigned<T>(u8, T);
    |
    = Box<dyn Any>
 query stack during panic:
-#0 [mir_built] preparing `<impl at $DIR/proc_macro_generated_packed.rs:15:10: 15:19>::eq` for borrow checking
+#0 [mir_built] building MIR for `<impl at $DIR/proc_macro_generated_packed.rs:15:10: 15:19>::eq`
 #1 [check_unsafety] unsafety-checking `<impl at $DIR/proc_macro_generated_packed.rs:15:10: 15:19>::eq`
 end of query stack
 error: aborting due to 1 previous error

tests/ui/type-alias-enum-variants/self-in-enum-definition.stderr

@@ -34,7 +34,7 @@ note: ...which requires const checking `Alpha::V3::{constant#0}`...
    |
 LL |     V3 = Self::V1 {} as u8 + 2,
    |          ^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires preparing `Alpha::V3::{constant#0}` for borrow checking...
+note: ...which requires building MIR for `Alpha::V3::{constant#0}`...
   --> $DIR/self-in-enum-definition.rs:5:10
    |
 LL |     V3 = Self::V1 {} as u8 + 2,