Extend the null check to borrowed places and remove AsmOutput places

Author: 1c3t3a

compiler/rustc_mir_transform/src/check_alignment.rs

@@ -20,7 +20,7 @@ impl<'tcx> crate::MirPass<'tcx> for CheckAlignment {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         // Skip trivially aligned place types.
         let excluded_pointees = [tcx.types.bool, tcx.types.i8, tcx.types.u8];
-        check_pointers(tcx, body, &excluded_pointees, insert_alignment_check);
+        check_pointers(tcx, body, &excluded_pointees, insert_alignment_check, false);
     }
 }
 

compiler/rustc_mir_transform/src/check_null.rs

@@ -14,7 +14,7 @@ impl<'tcx> crate::MirPass<'tcx> for CheckNull {
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        check_pointers(tcx, body, &[], insert_null_check);
+        check_pointers(tcx, body, &[], insert_null_check, true);
     }
 }
 

compiler/rustc_mir_transform/src/check_pointers.rs

@@ -35,6 +35,7 @@ pub(crate) fn check_pointers<'a, 'tcx, F>(
     body: &mut Body<'tcx>,
     excluded_pointees: &'a [Ty<'tcx>],
     on_finding: F,
+    check_for_borrows: bool,
 ) where
     F: Fn(
         /* tcx: */ TyCtxt<'tcx>,
@@ -66,7 +67,13 @@ pub(crate) fn check_pointers<'a, 'tcx, F>(
             let statement = &basic_blocks[block].statements[statement_index];
             let source_info = statement.source_info;
 
-            let mut finder = PointerFinder::new(tcx, local_decls, typing_env, excluded_pointees);
+            let mut finder = PointerFinder::new(
+                tcx,
+                local_decls,
+                typing_env,
+                excluded_pointees,
+                check_for_borrows,
+            );
             finder.visit_statement(statement, location);
 
             for (local, ty) in finder.into_found_pointers() {
@@ -110,6 +117,7 @@ struct PointerFinder<'a, 'tcx> {
     typing_env: ty::TypingEnv<'tcx>,
     pointers: Vec<(Place<'tcx>, Ty<'tcx>)>,
     excluded_pointees: &'a [Ty<'tcx>],
+    check_for_borrows: bool,
 }
 
 impl<'a, 'tcx> PointerFinder<'a, 'tcx> {
@@ -118,8 +126,16 @@ impl<'a, 'tcx> PointerFinder<'a, 'tcx> {
         local_decls: &'a mut LocalDecls<'tcx>,
         typing_env: ty::TypingEnv<'tcx>,
         excluded_pointees: &'a [Ty<'tcx>],
+        check_for_borrows: bool,
     ) -> Self {
-        PointerFinder { tcx, local_decls, typing_env, excluded_pointees, pointers: Vec::new() }
+        PointerFinder {
+            tcx,
+            local_decls,
+            typing_env,
+            excluded_pointees,
+            pointers: Vec::new(),
+            check_for_borrows,
+        }
     }
 
     fn into_found_pointers(self) -> Vec<(Place<'tcx>, Ty<'tcx>)> {
@@ -134,14 +150,16 @@ impl<'a, 'tcx> Visitor<'tcx> for PointerFinder<'a, 'tcx> {
         match context {
             PlaceContext::MutatingUse(
                 MutatingUseContext::Store
-                | MutatingUseContext::AsmOutput
                 | MutatingUseContext::Call
                 | MutatingUseContext::Yield
                 | MutatingUseContext::Drop,
             ) => {}
             PlaceContext::NonMutatingUse(
                 NonMutatingUseContext::Copy | NonMutatingUseContext::Move,
             ) => {}
+            PlaceContext::MutatingUse(MutatingUseContext::Borrow)
+            | PlaceContext::NonMutatingUse(NonMutatingUseContext::SharedBorrow)
+                if self.check_for_borrows => {}
             _ => {
                 return;
             }

tests/ui/mir/null/borrowed_mut_null.rs

@@ -0,0 +1,8 @@
+//@ run-fail
+//@ compile-flags: -C debug-assertions
+//@ error-pattern: null pointer dereference occured
+
+fn main() {
+    let ptr: *mut u32 = std::ptr::null_mut();
+    let _ptr: &mut u32 = unsafe { &mut *ptr };
+}

tests/ui/mir/null/use_null.rs renamed to tests/ui/mir/null/borrowed_null.rs

@@ -4,5 +4,5 @@
 
 fn main() {
     let ptr: *const u32 = std::ptr::null();
-    let _ptr = unsafe { *ptr };
+    let _ptr: &u32 = unsafe { &*ptr };
 }