Auto merge of #44249 - pnkfelix:debugflag-emit-end-regions, r=arielb1

Debugflag: -Z emit-end-regions

 Skip EndRegion emission by default. Use `-Z emit-end-regions` to reenable it.

The main intent is to fix cases where `EndRegion` emission is believed to be causing excess peak memory pressure.

It may also be a welcome change to people inspecting the MIR output who find the EndRegions to be a distraction.

(In later follow-up PR's I will put in safe-guards against using the current mir-borrowck without enabling `EndRegion` emission. But I wanted this PR to be minimal, in part because we may wish to backport it to the beta channel if we find that it reduces peak memory usage significantly.)

src/test/mir-opt/end_region_1.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions
+// compile-flags: -Z identify_regions -Z emit-end-regions
 // ignore-tidy-linelength
 
 // This is just about the simplest program that exhibits an EndRegion.

src/test/mir-opt/end_region_2.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions
+// compile-flags: -Z identify_regions -Z emit-end-regions
 // ignore-tidy-linelength
 
 // We will EndRegion for borrows in a loop that occur before break but

src/test/mir-opt/end_region_3.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions
+// compile-flags: -Z identify_regions -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Binding the borrow's subject outside the loop does not increase the

src/test/mir-opt/end_region_4.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions
+// compile-flags: -Z identify_regions -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Unwinding should EndRegion for in-scope borrows: Direct borrows.

src/test/mir-opt/end_region_5.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Unwinding should EndRegion for in-scope borrows: Borrowing via by-ref closure.

src/test/mir-opt/end_region_6.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Unwinding should EndRegion for in-scope borrows: 2nd borrow within by-ref closure.

src/test/mir-opt/end_region_7.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Unwinding should EndRegion for in-scope borrows: Borrow of moved data.

src/test/mir-opt/end_region_8.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Unwinding should EndRegion for in-scope borrows: Move of borrow into closure.

src/test/mir-opt/end_region_9.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // This test models a scenario that arielb1 found during review.

src/test/mir-opt/issue-43457.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: -Z identify_regions -Z span_free_formats
+// compile-flags: -Z identify_regions -Z span_free_formats -Z emit-end-regions
 // ignore-tidy-linelength
 
 // Regression test for #43457: an `EndRegion` was missing from output