Auto merge of rust-lang#2203 - RalfJung:deprecate, r=oli-obk

deprecate -Zmiri-allow-uninit-numbers and -Zmiri-allow-ptr-int-transmute

Cc rust-lang/miri#2187 rust-lang/miri#2188

Author: bors

README.md

@@ -309,13 +309,15 @@ to Miri failing to detect cases of undefined behavior in a program.
 
 * `-Zmiri-allow-uninit-numbers` disables the check to ensure that number types (integer and float
   types) always hold initialized data. (They must still be initialized when any actual operation,
-  such as arithmetic, is performed.) Using this flag is **unsound**. This has no effect when
+  such as arithmetic, is performed.) Using this flag is **unsound** and
+  [deprecated](https://github.com/rust-lang/miri/issues/2187). This has no effect when
   `-Zmiri-disable-validation` is present.
 * `-Zmiri-allow-ptr-int-transmute` makes Miri more accepting of transmutation between pointers and
   integers via `mem::transmute` or union/pointer type punning. This has two effects: it disables the
   check against integers storing a pointer (i.e., data with provenance), thus allowing
   pointer-to-integer transmutation, and it treats integer-to-pointer transmutation as equivalent to
-  a cast. Using this flag is **unsound**.
+  a cast. Using this flag is **unsound** and
+  [deprecated](https://github.com/rust-lang/miri/issues/2188).
 * `-Zmiri-disable-abi-check` disables checking [function ABI]. Using this flag
   is **unsound**.
 * `-Zmiri-disable-alignment-check` disables checking pointer alignment, so you

src/bin/miri.rs

@@ -329,8 +329,16 @@ fn main() {
                         since it is now enabled by default"
             );
         } else if arg == "-Zmiri-allow-uninit-numbers" {
+            eprintln!(
+                "WARNING: `-Zmiri-allow-uninit-numbers` is deprecated and planned to be removed. \
+                Please let us know at <https://github.com/rust-lang/miri/issues/2187> if you rely on this flag."
+            );
             miri_config.allow_uninit_numbers = true;
         } else if arg == "-Zmiri-allow-ptr-int-transmute" {
+            eprintln!(
+                "WARNING: `-Zmiri-allow-ptr-int-transmute` is deprecated and planned to be removed. \
+                Please let us know at <https://github.com/rust-lang/miri/issues/2188> if you rely on this flag."
+            );
             miri_config.allow_ptr_int_transmute = true;
         } else if arg == "-Zmiri-disable-abi-check" {
             miri_config.check_abi = false;

tests/fail/validity/invalid_enum_tag_256variants_uninit.stderr

@@ -1,3 +1,4 @@
+WARNING: `-Zmiri-allow-uninit-numbers` is deprecated and planned to be removed. Please let us know at <https://github.com/rust-lang/miri/issues/2187> if you rely on this flag.
 error: Undefined Behavior: type validation failed at .<enum-tag>: encountered uninitialized bytes, but expected a valid enum tag
   --> $DIR/invalid_enum_tag_256variants_uninit.rs:LL:CC
    |

tests/pass/move-uninit-primval.stderr

@@ -0,0 +1 @@
+WARNING: `-Zmiri-allow-uninit-numbers` is deprecated and planned to be removed. Please let us know at <https://github.com/rust-lang/miri/issues/2187> if you rely on this flag.

tests/pass/uninit_number_ignored.stderr

@@ -0,0 +1 @@
+WARNING: `-Zmiri-allow-uninit-numbers` is deprecated and planned to be removed. Please let us know at <https://github.com/rust-lang/miri/issues/2187> if you rely on this flag.