make Miri build again with rustc provenance changes

Author: RalfJung

src/diagnostics.rs

@@ -225,13 +225,14 @@ pub fn report_error<'tcx, 'mir>(
             let helps = match e.kind() {
                 Unsupported(
                     UnsupportedOpInfo::ThreadLocalStatic(_) |
-                    UnsupportedOpInfo::ReadExternStatic(_)
+                    UnsupportedOpInfo::ReadExternStatic(_) |
+                    UnsupportedOpInfo::PartialPointerOverwrite(_) | // we make memory uninit instead
+                    UnsupportedOpInfo::ReadPointerAsBytes
                 ) =>
                     panic!("Error should never be raised by Miri: {kind:?}", kind = e.kind()),
                 Unsupported(
                     UnsupportedOpInfo::Unsupported(_) |
-                    UnsupportedOpInfo::PartialPointerOverwrite(_) |
-                    UnsupportedOpInfo::ReadPointerAsBytes
+                    UnsupportedOpInfo::PartialPointerCopy(_)
                 ) =>
                     vec![(None, format!("this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support"))],
                 UndefinedBehavior(UndefinedBehaviorInfo::AlignmentCheckFailed { .. })

src/helpers.rs

@@ -757,7 +757,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         }
 
         // Step 2: get the bytes.
-        this.read_bytes_ptr(ptr, len)
+        this.read_bytes_ptr_strip_provenance(ptr, len)
     }
 
     fn read_wide_str(&self, mut ptr: Pointer<Option<Provenance>>) -> InterpResult<'tcx, Vec<u16>> {

src/machine.rs

@@ -205,6 +205,23 @@ impl interpret::Provenance for Provenance {
             Provenance::Wildcard => None,
         }
     }
+
+    fn join(left: Option<Self>, right: Option<Self>) -> Option<Self> {
+        match (left, right) {
+            // If one side is `None`, the result is `None`.
+            (None, _) | (_, None) => None,
+            // If one side is a wildcard, the best possible outcome is that it is equal to the other
+            // one, and we use that.
+            (Some(Provenance::Wildcard), o) | (o, Some(Provenance::Wildcard)) => o,
+            // If both are the *same* concrete tag, that is the result.
+            (
+                Some(Provenance::Concrete { alloc_id: left_alloc, sb: left_sb }),
+                Some(Provenance::Concrete { alloc_id: right_alloc, sb: right_sb }),
+            ) if left_alloc == right_alloc && left_sb == right_sb => left,
+            // Otherwise, fall back to `None`.
+            _ => None,
+        }
+    }
 }
 
 impl fmt::Debug for ProvenanceExtra {

src/shims/foreign_items.rs

@@ -560,8 +560,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 let n = Size::from_bytes(this.read_scalar(n)?.to_machine_usize(this)?);
 
                 let result = {
-                    let left_bytes = this.read_bytes_ptr(left, n)?;
-                    let right_bytes = this.read_bytes_ptr(right, n)?;
+                    let left_bytes = this.read_bytes_ptr_strip_provenance(left, n)?;
+                    let right_bytes = this.read_bytes_ptr_strip_provenance(right, n)?;
 
                     use std::cmp::Ordering::*;
                     match left_bytes.cmp(right_bytes) {
@@ -583,7 +583,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 let val = val as u8;
 
                 if let Some(idx) = this
-                    .read_bytes_ptr(ptr, Size::from_bytes(num))?
+                    .read_bytes_ptr_strip_provenance(ptr, Size::from_bytes(num))?
                     .iter()
                     .rev()
                     .position(|&c| c == val)
@@ -606,7 +606,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 let val = val as u8;
 
                 let idx = this
-                    .read_bytes_ptr(ptr, Size::from_bytes(num))?
+                    .read_bytes_ptr_strip_provenance(ptr, Size::from_bytes(num))?
                     .iter()
                     .position(|&c| c == val);
                 if let Some(idx) = idx {

src/shims/unix/fs.rs

@@ -761,7 +761,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let communicate = this.machine.communicate();
 
         if let Some(file_descriptor) = this.machine.file_handler.handles.get(&fd) {
-            let bytes = this.read_bytes_ptr(buf, Size::from_bytes(count))?;
+            let bytes = this.read_bytes_ptr_strip_provenance(buf, Size::from_bytes(count))?;
             let result =
                 file_descriptor.write(communicate, bytes)?.map(|c| i64::try_from(c).unwrap());
             this.try_unwrap_io_result(result)

src/shims/windows/dlsym.rs

@@ -78,7 +78,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     // stdout/stderr
                     use std::io::{self, Write};
 
-                    let buf_cont = this.read_bytes_ptr(buf, Size::from_bytes(u64::from(n)))?;
+                    let buf_cont =
+                        this.read_bytes_ptr_strip_provenance(buf, Size::from_bytes(u64::from(n)))?;
                     let res = if this.machine.mute_stdout_stderr {
                         Ok(buf_cont.len())
                     } else if handle == -11 {