Auto merge of #85607 - LeSeulArtichaut:thir-unsafeck-closures, r=nikomatsakis

Make closures inherit their parent's "safety context"

Fixes rust-lang/project-thir-unsafeck#9, ~~blocked on #85273~~.
r? `@nikomatsakis`

Author: bors

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -213,6 +213,30 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                     self.requires_unsafe(expr.span, CastOfPointerToInt);
                 }
             }
+            ExprKind::Closure {
+                closure_id,
+                substs: _,
+                upvars: _,
+                movability: _,
+                fake_reads: _,
+            } => {
+                let closure_id = closure_id.expect_local();
+                let closure_def = if let Some((did, const_param_id)) =
+                    ty::WithOptConstParam::try_lookup(closure_id, self.tcx)
+                {
+                    ty::WithOptConstParam { did, const_param_did: Some(const_param_id) }
+                } else {
+                    ty::WithOptConstParam::unknown(closure_id)
+                };
+                let (closure_thir, expr) = self.tcx.thir_body(closure_def);
+                let closure_thir = &closure_thir.borrow();
+                let hir_context = self.tcx.hir().local_def_id_to_hir_id(closure_id);
+                let mut closure_visitor =
+                    UnsafetyVisitor { thir: closure_thir, hir_context, ..*self };
+                closure_visitor.visit_expr(&closure_thir[expr]);
+                // Unsafe blocks can be used in closures, make sure to take it into account
+                self.safety_context = closure_visitor.safety_context;
+            }
             _ => {}
         }
 
@@ -335,14 +359,18 @@ impl UnsafeOpKind {
     }
 }
 
-// FIXME: checking unsafety for closures should be handled by their parent body,
-// as they inherit their "safety context" from their declaration site.
 pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>) {
     // THIR unsafeck is gated under `-Z thir-unsafeck`
     if !tcx.sess.opts.debugging_opts.thir_unsafeck {
         return;
     }
 
+    // Closures are handled by their parent function
+    if tcx.is_closure(def.did.to_def_id()) {
+        tcx.ensure().thir_check_unsafety(tcx.hir().local_def_id_to_hir_id(def.did).owner);
+        return;
+    }
+
     let (thir, expr) = tcx.thir_body(def);
     let thir = &thir.borrow();
     // If `thir` is empty, a type error occured, skip this body.

src/test/ui/async-await/async-await.rs

@@ -1,7 +1,8 @@
 // run-pass
 
-// revisions: default nomiropt
+// revisions: default nomiropt thirunsafeck
 //[nomiropt]compile-flags: -Z mir-opt-level=0
+//[thirunsafeck]compile-flags: -Zthir-unsafeck
 
 #![allow(unused)]
 

src/test/ui/command/command-pre-exec.rs

@@ -1,4 +1,6 @@
 // run-pass
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
 
 #![allow(stable_features)]
 // ignore-windows - this is a unix-specific test

src/test/ui/generator/static-mut-reference-across-yield.rs

@@ -1,4 +1,7 @@
 // build-pass
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
+
 #![feature(generators)]
 
 static mut A: [i32; 5] = [1, 2, 3, 4, 5];

src/test/ui/intrinsics/panic-uninitialized-zeroed.rs

@@ -1,5 +1,7 @@
 // run-pass
 // ignore-wasm32-bare compiled with panic=abort by default
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
 
 // This test checks panic emitted from `mem::{uninitialized,zeroed}`.
 

src/test/ui/issues/issue-11740.rs

@@ -1,4 +1,6 @@
 // check-pass
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
 
 struct Attr {
     name: String,

src/test/ui/issues/issue-39367.rs

@@ -1,4 +1,7 @@
 // run-pass
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
+
 use std::ops::Deref;
 
 struct ArenaSet<U: Deref, V=<U as Deref>::Target>(U, &'static V)

src/test/ui/issues/issue-45107-unnecessary-unsafe-in-closure.stderr renamed to src/test/ui/issues/issue-45107-unnecessary-unsafe-in-closure.mir.stderr

@@ -1,5 +1,5 @@
 error: unnecessary `unsafe` block
-  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:7:13
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:10:13
    |
 LL |     unsafe {
    |     ------ because it's nested under this `unsafe` block
@@ -8,13 +8,13 @@ LL |             unsafe {
    |             ^^^^^^ unnecessary `unsafe` block
    |
 note: the lint level is defined here
-  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:1:8
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:4:8
    |
 LL | #[deny(unused_unsafe)]
    |        ^^^^^^^^^^^^^
 
 error: unnecessary `unsafe` block
-  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:9:38
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:12:38
    |
 LL |     unsafe {
    |     ------ because it's nested under this `unsafe` block
@@ -23,7 +23,7 @@ LL |                 |w: &mut Vec<u32>| { unsafe {
    |                                      ^^^^^^ unnecessary `unsafe` block
 
 error: unnecessary `unsafe` block
-  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:13:34
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:16:34
    |
 LL |     unsafe {
    |     ------ because it's nested under this `unsafe` block

src/test/ui/issues/issue-45107-unnecessary-unsafe-in-closure.rs

@@ -1,3 +1,6 @@
+// revisions: mir thir
+// [thir]compile-flags: -Zthir-unsafeck
+
 #[deny(unused_unsafe)]
 fn main() {
     let mut v = Vec::<i32>::with_capacity(24);

src/test/ui/issues/issue-45107-unnecessary-unsafe-in-closure.thir.stderr

@@ -0,0 +1,35 @@
+error: unnecessary `unsafe` block
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:10:13
+   |
+LL |     unsafe {
+   |     ------ because it's nested under this `unsafe` block
+LL |         let f = |v: &mut Vec<_>| {
+LL |             unsafe {
+   |             ^^^^^^ unnecessary `unsafe` block
+   |
+note: the lint level is defined here
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:4:8
+   |
+LL | #[deny(unused_unsafe)]
+   |        ^^^^^^^^^^^^^
+
+error: unnecessary `unsafe` block
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:12:38
+   |
+LL |     unsafe {
+   |     ------ because it's nested under this `unsafe` block
+...
+LL |                 |w: &mut Vec<u32>| { unsafe {
+   |                                      ^^^^^^ unnecessary `unsafe` block
+
+error: unnecessary `unsafe` block
+  --> $DIR/issue-45107-unnecessary-unsafe-in-closure.rs:16:34
+   |
+LL |     unsafe {
+   |     ------ because it's nested under this `unsafe` block
+...
+LL |             |x: &mut Vec<u32>| { unsafe {
+   |                                  ^^^^^^ unnecessary `unsafe` block
+
+error: aborting due to 3 previous errors
+