Auto merge of rust-lang#118216 - lqd:constraint-generation-non-non, r=matthewjasper

Refactor NLL constraint generation and most of polonius fact generation

As discussed in rust-lang#118175, NLL "constraint generation" is only about liveness, but currently also contains legacy polonius fact generation. The latter is quite messy, and this PR cleans this up to prepare for its future removal:

- splits polonius fact generation out of NLL constraint generation
- merges NLL constraint generation to its more natural place, liveness
- extracts all of the polonius fact generation from NLLs apart from MIR typeck (as fact generation is somewhat in a single place there already, but should be cleaned up) into its own explicit module, with a single entry point instead of many.

There should be no behavior changes, and tests seem to behave the same as master: without polonius, with legacy polonius, with the in-tree polonius.

I've split everything into smaller logical commits for easier review, as it required quite a bit of code to be split and moved around, but it should all be trivial changes.

r? `@matthewjasper`

Author: bors

compiler/rustc_borrowck/src/constraint_generation.rs

@@ -65,19 +65,18 @@ use self::path_utils::*;
 
 pub mod borrow_set;
 mod borrowck_errors;
-mod constraint_generation;
 mod constraints;
 mod dataflow;
 mod def_use;
 mod diagnostics;
 mod facts;
-mod invalidation;
 mod location;
 mod member_constraints;
 mod nll;
 mod path_utils;
 mod place_ext;
 mod places_conflict;
+mod polonius;
 mod prefixes;
 mod region_infer;
 mod renumber;
@@ -195,8 +194,7 @@ fn do_mir_borrowck<'tcx>(
         nll::replace_regions_in_mir(&infcx, param_env, &mut body_owned, &mut promoted);
     let body = &body_owned; // no further changes
 
-    let location_table_owned = LocationTable::new(body);
-    let location_table = &location_table_owned;
+    let location_table = LocationTable::new(body);
 
     let move_data = MoveData::gather_moves(body, tcx, param_env, |_| true);
     let promoted_move_data = promoted
@@ -228,7 +226,7 @@ fn do_mir_borrowck<'tcx>(
         free_regions,
         body,
         &promoted,
-        location_table,
+        &location_table,
         param_env,
         &mut flow_inits,
         &mdpe.move_data,
@@ -292,7 +290,7 @@ fn do_mir_borrowck<'tcx>(
             param_env,
             body: promoted_body,
             move_data: &move_data,
-            location_table, // no need to create a real one for the promoted, it is not used
+            location_table: &location_table, // no need to create a real one for the promoted, it is not used
             movable_coroutine,
             fn_self_span_reported: Default::default(),
             locals_are_invalidated_at_exit,
@@ -333,7 +331,7 @@ fn do_mir_borrowck<'tcx>(
         param_env,
         body,
         move_data: &mdpe.move_data,
-        location_table,
+        location_table: &location_table,
         movable_coroutine,
         locals_are_invalidated_at_exit,
         fn_self_span_reported: Default::default(),
@@ -435,7 +433,7 @@ fn do_mir_borrowck<'tcx>(
             promoted,
             borrow_set,
             region_inference_context: regioncx,
-            location_table: polonius_input.as_ref().map(|_| location_table_owned),
+            location_table: polonius_input.as_ref().map(|_| location_table),
             input_facts: polonius_input,
             output_facts,
         }))
@@ -1020,9 +1018,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         flow_state: &Flows<'cx, 'tcx>,
     ) -> bool {
         let mut error_reported = false;
-        let tcx = self.infcx.tcx;
-        let body = self.body;
-        let borrow_set = self.borrow_set.clone();
+        let borrow_set = Rc::clone(&self.borrow_set);
 
         // Use polonius output if it has been enabled.
         let mut polonius_output;
@@ -1039,8 +1035,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         each_borrow_involving_path(
             self,
-            tcx,
-            body,
+            self.infcx.tcx,
+            self.body,
             location,
             (sd, place_span.0),
             &borrow_set,