Rollup merge of #147876 - Shunpoco:lint-check-tainted-error, r=oli-obk

Check tainted_by_error in LateLint

## Context
This PR continues from #138679 (comment).
In the last PR, I introduced typeck result's tainted_by_error in check_pat. But as we've discussed, I should put the check to a better place which all lints get benefit from the check.

## Change
Since visit_nested_body in late.rs is the starting point of late lint for a nested body, I moved the error check to the function.
I also rename one ui test case which I introduced in the last PR. I think the new name describes what the test wants to check more.

This PR fixes #138361 .

Note that we need to use actually_rustdoc to call typeck_body() in visit_nested_body. Otherwise rustdoc returns an error. However, as its comment describes we shouldn't use actually_rustdoc if there is an alternative solution. So far I only come up with using actually_rustdoc (this change), or checking tainted_by_error in each check_xxx functions (e.g., check on check_pat in #138679, and on check_expr for #138361).

Author: JonathanBrouwer

compiler/rustc_lint/src/builtin.rs

@@ -148,10 +148,7 @@ declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
 
 impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
     fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) {
-        // The result shouldn't be tainted, otherwise it will cause ICE.
-        if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind
-            && cx.typeck_results().tainted_by_errors.is_none()
-        {
+        if let PatKind::Struct(ref qpath, field_pats, _) = pat.kind {
             let variant = cx
                 .typeck_results()
                 .pat_ty(pat)

compiler/rustc_lint/src/late.rs

@@ -99,7 +99,15 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
         // The body and typeck results are also set in `visit_fn`.
         // Only fetch the results if this is for a new body.
         if old_enclosing_body != Some(body_id) && !self.actually_rustdoc {
-            self.context.typeck_results = Some(self.context.tcx.typeck_body(body_id));
+            let typeck_results = self.context.tcx.typeck_body(body_id);
+
+            // To avoid ICE, skip visiting the body if the typeck_results is tainted.
+            if typeck_results.tainted_by_errors.is_some() {
+                self.context.enclosing_body = old_enclosing_body;
+                self.context.typeck_results = old_typeck_results;
+                return;
+            }
+            self.context.typeck_results = Some(typeck_results);
         }
 
         let body = self.context.tcx.hir_body(body_id);
@@ -189,7 +197,16 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
         let old_enclosing_body = self.context.enclosing_body.replace(body_id);
         let old_typeck_results = self.context.typeck_results;
         if !self.actually_rustdoc {
-            self.context.typeck_results = Some(self.context.tcx.typeck_body(body_id));
+            let typeck_results = self.context.tcx.typeck_body(body_id);
+
+            // To avoid ICE, skip visiting the body if the typeck_results is tainted.
+            if typeck_results.tainted_by_errors.is_some() {
+                self.context.enclosing_body = old_enclosing_body;
+                self.context.typeck_results = old_typeck_results;
+                return;
+            }
+
+            self.context.typeck_results = Some(typeck_results);
         }
         let body = self.context.tcx.hir_body(body_id);
         lint_callback!(self, check_fn, fk, decl, body, span, id);

tests/crashes/138361.rs

@@ -1,13 +1,13 @@
 error: constant evaluation is taking a long time
-  --> $DIR/do-not-ice-long-constant-evaluation-in-for-loop.rs:10:14
+  --> $DIR/long-constant-evaluation-cause-dead-code.rs:10:14
    |
 LL |         [(); loop {}];
    |              ^^^^^^^
    |
    = note: this lint makes sure the compiler doesn't get stuck due to infinite loops in const eval.
            If your compilation actually takes a long time, you can safely allow the lint
 help: the constant being evaluated
-  --> $DIR/do-not-ice-long-constant-evaluation-in-for-loop.rs:10:14
+  --> $DIR/long-constant-evaluation-cause-dead-code.rs:10:14
    |
 LL |         [(); loop {}];
    |              ^^^^^^^

…-long-constant-evaluation-in-for-loop.rs …g-constant-evaluation-cause-dead-code.rstests/ui/consts/do-not-ice-long-constant-evaluation-in-for-loop.rs renamed to tests/ui/consts/long-constant-evaluation-cause-dead-code.rs tests/ui/consts/do-not-ice-long-constant-evaluation-in-for-loop.rs renamed to tests/ui/consts/long-constant-evaluation-cause-dead-code.rs

@@ -0,0 +1,5 @@
+// The test confirms ICE-138361 is fixed.
+fn main() {
+  [0; loop{}]; //~ ERROR constant evaluation is taking a long time
+  std::mem::transmute(4)
+}

…g-constant-evaluation-in-for-loop.stderr …nstant-evaluation-cause-dead-code.stderrtests/ui/consts/do-not-ice-long-constant-evaluation-in-for-loop.stderr renamed to tests/ui/consts/long-constant-evaluation-cause-dead-code.stderr tests/ui/consts/do-not-ice-long-constant-evaluation-in-for-loop.stderr renamed to tests/ui/consts/long-constant-evaluation-cause-dead-code.stderr

@@ -0,0 +1,17 @@
+error: constant evaluation is taking a long time
+  --> $DIR/long-constant-evaluation-cause-ice-in-sty.rs:3:7
+   |
+LL |   [0; loop{}];
+   |       ^^^^^^
+   |
+   = note: this lint makes sure the compiler doesn't get stuck due to infinite loops in const eval.
+           If your compilation actually takes a long time, you can safely allow the lint
+help: the constant being evaluated
+  --> $DIR/long-constant-evaluation-cause-ice-in-sty.rs:3:7
+   |
+LL |   [0; loop{}];
+   |       ^^^^^^
+   = note: `#[deny(long_running_const_eval)]` on by default
+
+error: aborting due to 1 previous error
+