Auto merge of #89019 - Manishearth:rollup-5qp8a5s, r=Manishearth

Rollup of 10 pull requests

Successful merges:

 - #88292 (Enable --generate-link-to-definition for rustc's docs)
 - #88729 (Recover from `Foo(a: 1, b: 2)`)
 - #88875 (cleanup(rustc_trait_selection): remove vestigial code from rustc_on_unimplemented)
 - #88892 (Move object safety suggestions to the end of the error)
 - #88928 (Document the closure arguments for `reduce`.)
 - #88976 (Clean up and add doc comments for CStr)
 - #88983 (Allow calling `get_body_with_borrowck_facts` without `-Z polonius`)
 - #88985 (Update clobber_abi list to include k[1-7] regs)
 - #88986 (Update the backtrace crate)
 - #89009 (Fix typo in `break` docs)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_borrowck/src/consumers.rs

@@ -14,16 +14,16 @@ pub use super::{
 };
 
 /// This function computes Polonius facts for the given body. It makes a copy of
-/// the body because it needs to regenerate the region identifiers.
+/// the body because it needs to regenerate the region identifiers. This function
+/// should never be invoked during a typical compilation session due to performance
+/// issues with Polonius.
 ///
 /// Note:
 /// *   This function will panic if the required body was already stolen. This
 ///     can, for example, happen when requesting a body of a `const` function
 ///     because they are evaluated during typechecking. The panic can be avoided
 ///     by overriding the `mir_borrowck` query. You can find a complete example
 ///     that shows how to do this at `src/test/run-make/obtain-borrowck/`.
-/// *   This function will also panic if computation of Polonius facts
-///     (`-Zpolonius` flag) is not enabled.
 ///
 /// *   Polonius is highly unstable, so expect regular changes in its signature or other details.
 pub fn get_body_with_borrowck_facts<'tcx>(

compiler/rustc_borrowck/src/lib.rs

@@ -154,11 +154,6 @@ fn do_mir_borrowck<'a, 'tcx>(
 
     debug!("do_mir_borrowck(def = {:?})", def);
 
-    assert!(
-        !return_body_with_facts || infcx.tcx.sess.opts.debugging_opts.polonius,
-        "borrowck facts can be requested only when Polonius is enabled"
-    );
-
     let tcx = infcx.tcx;
     let param_env = tcx.param_env(def.did);
     let id = tcx.hir().local_def_id_to_hir_id(def.did);
@@ -235,6 +230,8 @@ fn do_mir_borrowck<'a, 'tcx>(
     let borrow_set =
         Rc::new(BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &mdpe.move_data));
 
+    let use_polonius = return_body_with_facts || infcx.tcx.sess.opts.debugging_opts.polonius;
+
     // Compute non-lexical lifetimes.
     let nll::NllOutput {
         regioncx,
@@ -254,6 +251,7 @@ fn do_mir_borrowck<'a, 'tcx>(
         &mdpe.move_data,
         &borrow_set,
         &upvars,
+        use_polonius,
     );
 
     // Dump MIR results into a file, if that is enabled. This let us