extract main NLL MIR dump function

this will allow calling from polonius MIR

compiler/rustc_borrowck/src/nll.rs

@@ -232,40 +232,7 @@ pub(super) fn dump_nll_mir<'tcx>(
         &0,
         body,
         |pass_where, out| {
-            match pass_where {
-                // Before the CFG, dump out the values for each region variable.
-                PassWhere::BeforeCFG => {
-                    regioncx.dump_mir(tcx, out)?;
-                    writeln!(out, "|")?;
-
-                    if let Some(closure_region_requirements) = closure_region_requirements {
-                        writeln!(out, "| Free Region Constraints")?;
-                        for_each_region_constraint(tcx, closure_region_requirements, &mut |msg| {
-                            writeln!(out, "| {msg}")
-                        })?;
-                        writeln!(out, "|")?;
-                    }
-
-                    if borrow_set.len() > 0 {
-                        writeln!(out, "| Borrows")?;
-                        for (borrow_idx, borrow_data) in borrow_set.iter_enumerated() {
-                            writeln!(
-                                out,
-                                "| {:?}: issued at {:?} in {:?}",
-                                borrow_idx, borrow_data.reserve_location, borrow_data.region
-                            )?;
-                        }
-                        writeln!(out, "|")?;
-                    }
-                }
-
-                PassWhere::BeforeLocation(_) => {}
-
-                PassWhere::AfterTerminator(_) => {}
-
-                PassWhere::BeforeBlock(_) | PassWhere::AfterLocation(_) | PassWhere::AfterCFG => {}
-            }
-            Ok(())
+            emit_nll_mir(tcx, regioncx, closure_region_requirements, borrow_set, pass_where, out)
         },
         options,
     );
@@ -283,6 +250,51 @@ pub(super) fn dump_nll_mir<'tcx>(
     };
 }
 
+/// Produces the actual NLL MIR sections to emit during the dumping process.
+pub(crate) fn emit_nll_mir<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    regioncx: &RegionInferenceContext<'tcx>,
+    closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
+    borrow_set: &BorrowSet<'tcx>,
+    pass_where: PassWhere,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    match pass_where {
+        // Before the CFG, dump out the values for each region variable.
+        PassWhere::BeforeCFG => {
+            regioncx.dump_mir(tcx, out)?;
+            writeln!(out, "|")?;
+
+            if let Some(closure_region_requirements) = closure_region_requirements {
+                writeln!(out, "| Free Region Constraints")?;
+                for_each_region_constraint(tcx, closure_region_requirements, &mut |msg| {
+                    writeln!(out, "| {msg}")
+                })?;
+                writeln!(out, "|")?;
+            }
+
+            if borrow_set.len() > 0 {
+                writeln!(out, "| Borrows")?;
+                for (borrow_idx, borrow_data) in borrow_set.iter_enumerated() {
+                    writeln!(
+                        out,
+                        "| {:?}: issued at {:?} in {:?}",
+                        borrow_idx, borrow_data.reserve_location, borrow_data.region
+                    )?;
+                }
+                writeln!(out, "|")?;
+            }
+        }
+
+        PassWhere::BeforeLocation(_) => {}
+
+        PassWhere::AfterTerminator(_) => {}
+
+        PassWhere::BeforeBlock(_) | PassWhere::AfterLocation(_) | PassWhere::AfterCFG => {}
+    }
+    Ok(())
+}
+
 #[allow(rustc::diagnostic_outside_of_impl)]
 #[allow(rustc::untranslatable_diagnostic)]
 pub(super) fn dump_annotation<'tcx, 'infcx>(

compiler/rustc_middle/src/mir/pretty.rs

@@ -23,6 +23,7 @@ pub(crate) const ALIGN: usize = 40;
 
 /// An indication of where we are in the control flow graph. Used for printing
 /// extra information in `dump_mir`
+#[derive(Clone)]
 pub enum PassWhere {
     /// We have not started dumping the control flow graph, but we are about to.
     BeforeCFG,