Rollup merge of #143327 - RalfJung:miri-type-validity-error, r=oli-obk

miri: improve errors for type validity assertion failures

Miri has pretty nice errors for type validity violations, printing which field in the type the problem occurs at and so on.

However, we don't see these errors when using e.g. `mem::zeroed` as that uses `assert_zero_valid` to bail out before Miri can detect the UB.

Similar to what we did with `@saethlin's` UB checks, I think we should disable such language UB checks in Miri so that we can get better error messages. If we go for this we should probably say this in the intrinsic docs as well so that people don't think they can rely on these intrinsics catching anything.

Furthermore, I slightly changed `MaybeUninit::assume_init` so that the `.value` field does not show up in error messages any more.

`@rust-lang/miri` what do you think?

10 files changed, 27 insertions, 62 deletions

diff --git a/src/tools/miri/src/intrinsics/mod.rs b/src/tools/miri/src/intrinsics/mod.rs
index ed1851a19ae..4efa7dd4dcf 100644
--- a/src/tools/miri/src/intrinsics/mod.rs
+++ b/src/tools/miri/src/intrinsics/mod.rs
@@ -457,6 +457,10 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 throw_machine_stop!(TerminationInfo::Abort(format!("trace/breakpoint trap")))
             }
 
+            "assert_inhabited" | "assert_zero_valid" | "assert_mem_uninitialized_valid" => {
+                // Make these a NOP, so we get the better Miri-native error messages.
+            }
+
             _ => return interp_ok(EmulateItemResult::NotSupported),
         }
 
diff --git a/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs b/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs
index dd2dd346231..1dc334486c3 100644
--- a/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs
+++ b/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs
@@ -20,7 +20,7 @@ fn main() {
         let mut buf: MaybeUninit<[u8; 4]> = std::mem::MaybeUninit::uninit();
         // Read 4 bytes from a 3-byte file.
         assert_eq!(libc::read(fd, buf.as_mut_ptr().cast::<std::ffi::c_void>(), 4), 3);
-        buf.assume_init(); //~ERROR: Undefined Behavior: constructing invalid value at .value[3]: encountered uninitialized memory, but expected an integer
+        buf.assume_init(); //~ERROR: encountered uninitialized memory, but expected an integer
         assert_eq!(libc::close(fd), 0);
     }
     remove_file(&path).unwrap();
diff --git a/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.stderr b/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.stderr
index fadb31e3a8f..83119f087ff 100644
--- a/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.stderr
+++ b/src/tools/miri/tests/fail-dep/libc/libc-read-and-uninit-premature-eof.stderr
@@ -1,8 +1,8 @@
-error: Undefined Behavior: constructing invalid value at .value[3]: encountered uninitialized memory, but expected an integer
+error: Undefined Behavior: constructing invalid value at [3]: encountered uninitialized memory, but expected an integer
   --> tests/fail-dep/libc/libc-read-and-uninit-premature-eof.rs:LL:CC
    |
-LL | ...   buf.assume_init();
-   |       ^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+LL |         buf.assume_init();
+   |         ^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
diff --git a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.rs b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.rs
index dd3246d8120..34fef6b9ee5 100644
--- a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.rs
+++ b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.rs
@@ -1,11 +1,6 @@
-//@normalize-stderr-test: "\|.*::abort\(\).*" -> "| ABORT()"
-//@normalize-stderr-test: "\| +\^+" -> "| ^"
-//@normalize-stderr-test: "\n +[0-9]+:[^\n]+" -> ""
-//@normalize-stderr-test: "\n +at [^\n]+" -> ""
-//@error-in-other-file: aborted execution
 #![feature(never_type)]
 
 #[allow(deprecated, invalid_value)]
 fn main() {
-    let _ = unsafe { std::mem::uninitialized::<!>() };
+    let _ = unsafe { std::mem::uninitialized::<!>() }; //~ERROR: constructing invalid value
 }
diff --git a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
index 3db8a5be205..36642208afe 100644
--- a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
@@ -1,27 +1,13 @@
-
-thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
-aborted execution: attempted to instantiate uninhabited type `!`
-note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
-note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
-thread caused non-unwinding panic. aborting.
-error: abnormal termination: the program aborted execution
-  --> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
-   |
-LL | ABORT()
-   | ^ abnormal termination occurred here
-   |
-   = note: BACKTRACE:
-   = note: inside `std::sys::pal::PLATFORM::abort_internal` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
-   = note: inside `std::panicking::rust_panic_with_hook` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside closure at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `std::sys::backtrace::__rust_end_short_backtrace::<{closure@std::panicking::begin_panic_handler::{closure#0}}, !>` at RUSTLIB/std/src/sys/backtrace.rs:LL:CC
-   = note: inside `std::panicking::begin_panic_handler` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `core::panicking::panic_nounwind` at RUSTLIB/core/src/panicking.rs:LL:CC
-note: inside `main`
+error: Undefined Behavior: constructing invalid value: encountered a value of the never type `!`
   --> tests/fail/intrinsics/uninit_uninhabited_type.rs:LL:CC
    |
 LL |     let _ = unsafe { std::mem::uninitialized::<!>() };
-   | ^
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at tests/fail/intrinsics/uninit_uninhabited_type.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
diff --git a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.rs b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.rs
index 3d355bad626..cca2c5ae984 100644
--- a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.rs
+++ b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.rs
@@ -1,10 +1,4 @@
-//@normalize-stderr-test: "\|.*::abort\(\).*" -> "| ABORT()"
-//@normalize-stderr-test: "\| +\^+" -> "| ^"
-//@normalize-stderr-test: "\n +[0-9]+:[^\n]+" -> ""
-//@normalize-stderr-test: "\n +at [^\n]+" -> ""
-//@error-in-other-file: aborted execution
-
 #[allow(deprecated, invalid_value)]
 fn main() {
-    let _ = unsafe { std::mem::zeroed::<fn()>() };
+    let _ = unsafe { std::mem::zeroed::<fn()>() }; //~ERROR: constructing invalid value
 }
diff --git a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
index a1e476328b0..53f3f8d1404 100644
--- a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
@@ -1,27 +1,13 @@
-
-thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
-aborted execution: attempted to zero-initialize type `fn()`, which is invalid
-note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
-note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
-thread caused non-unwinding panic. aborting.
-error: abnormal termination: the program aborted execution
-  --> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
-   |
-LL | ABORT()
-   | ^ abnormal termination occurred here
-   |
-   = note: BACKTRACE:
-   = note: inside `std::sys::pal::PLATFORM::abort_internal` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
-   = note: inside `std::panicking::rust_panic_with_hook` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside closure at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `std::sys::backtrace::__rust_end_short_backtrace::<{closure@std::panicking::begin_panic_handler::{closure#0}}, !>` at RUSTLIB/std/src/sys/backtrace.rs:LL:CC
-   = note: inside `std::panicking::begin_panic_handler` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `core::panicking::panic_nounwind` at RUSTLIB/core/src/panicking.rs:LL:CC
-note: inside `main`
+error: Undefined Behavior: constructing invalid value: encountered a null function pointer
   --> tests/fail/intrinsics/zero_fn_ptr.rs:LL:CC
    |
 LL |     let _ = unsafe { std::mem::zeroed::<fn()>() };
-   | ^
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at tests/fail/intrinsics/zero_fn_ptr.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
diff --git a/src/tools/miri/tests/fail/validity/uninit_float.stderr b/src/tools/miri/tests/fail/validity/uninit_float.stderr
index 1b948b062e1..0c859d72764 100644
--- a/src/tools/miri/tests/fail/validity/uninit_float.stderr
+++ b/src/tools/miri/tests/fail/validity/uninit_float.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: constructing invalid value at .value[0]: encountered uninitialized memory, but expected a floating point number
+error: Undefined Behavior: constructing invalid value at [0]: encountered uninitialized memory, but expected a floating point number
   --> tests/fail/validity/uninit_float.rs:LL:CC
    |
 LL |     let _val: [f32; 1] = unsafe { std::mem::uninitialized() };
diff --git a/src/tools/miri/tests/fail/validity/uninit_integer.stderr b/src/tools/miri/tests/fail/validity/uninit_integer.stderr
index b17bdee65da..5d31e2659ee 100644
--- a/src/tools/miri/tests/fail/validity/uninit_integer.stderr
+++ b/src/tools/miri/tests/fail/validity/uninit_integer.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: constructing invalid value at .value[0]: encountered uninitialized memory, but expected an integer
+error: Undefined Behavior: constructing invalid value at [0]: encountered uninitialized memory, but expected an integer
   --> tests/fail/validity/uninit_integer.rs:LL:CC
    |
 LL |     let _val = unsafe { std::mem::MaybeUninit::<[usize; 1]>::uninit().assume_init() };
diff --git a/src/tools/miri/tests/fail/validity/uninit_raw_ptr.stderr b/src/tools/miri/tests/fail/validity/uninit_raw_ptr.stderr
index 269af6061c2..d2e9408adbe 100644
--- a/src/tools/miri/tests/fail/validity/uninit_raw_ptr.stderr
+++ b/src/tools/miri/tests/fail/validity/uninit_raw_ptr.stderr
@@ -1,4 +1,4 @@
-error: Undefined Behavior: constructing invalid value at .value[0]: encountered uninitialized memory, but expected a raw pointer
+error: Undefined Behavior: constructing invalid value at [0]: encountered uninitialized memory, but expected a raw pointer
   --> tests/fail/validity/uninit_raw_ptr.rs:LL:CC
    |
 LL |     let _val = unsafe { std::mem::MaybeUninit::<[*const u8; 1]>::uninit().assume_init() };