Auto merge of #134523 - dingxiangfei2009:issue-130836-attempt-2, r=nikomatsakis

Run borrowck tests on BIDs and emit tail-expr-drop-order lints for violations

Fix #132861

r? `@nikomatsakis`
cc `@compiler-errors`

This patch enlarges the scope where the `tail-expr-drop-order` lint applies, so that all locals involved in tail expressions are inspected. This is necessary to run borrow-checking to capture the cases where it used to compile under Edition 2021 but is not going to pass borrow-checking from Edition 2024 onwards.

The way it works is to inspect each BID against the set of borrows that are still live. If the local involved in BID has a borrow index which happens to be live as well at the location of this BID statement, in the future this will be a borrow-checking violation. The lint will fire in this case.

1 files changed, 6 insertions, 1 deletions

diff --git a/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs b/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs
index e5a183bc75c..6590702118c 100644
--- a/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs
+++ b/compiler/rustc_mir_transform/src/lint_tail_expr_drop_order.rs
@@ -351,6 +351,11 @@ pub(crate) fn run_lint<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId, body: &Body<
     {
         return;
     }
+
+    // FIXME(typing_env): This should be able to reveal the opaques local to the
+    // body using the typeck results.
+    let typing_env = ty::TypingEnv::non_body_analysis(tcx, def_id);
+
     // ## About BIDs in blocks ##
     // Track the set of blocks that contain a backwards-incompatible drop (BID)
     // and, for each block, the vector of locations.
@@ -358,7 +363,7 @@ pub(crate) fn run_lint<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId, body: &Body<
     // We group them per-block because they tend to scheduled in the same drop ladder block.
     let mut bid_per_block = IndexMap::default();
     let mut bid_places = UnordSet::new();
-    let typing_env = ty::TypingEnv::post_analysis(tcx, def_id);
+
     let mut ty_dropped_components = UnordMap::default();
     for (block, data) in body.basic_blocks.iter_enumerated() {
         for (statement_index, stmt) in data.statements.iter().enumerate() {