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Rollup merge of #101101 - RalfJung:read-pointer-as-bytes, r=oli-obk

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interpret: make read-pointer-as-bytes a CTFE-only error with extra information

Next step in the reaction to https://github.com/rust-lang/rust/issues/99923. Also teaches Miri to implicitly strip provenance in more situations when transmuting pointers to integers, which fixes https://github.com/rust-lang/miri/issues/2456.

Pointer-to-int transmutation during CTFE now produces a message like this:
```
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
```

r? ``@oli-obk``
This commit is contained in:
Dylan DPC 2022-08-30 11:26:51 +05:30 • committed by GitHub
commit 81f3841cfb
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46 changed files with 631 additions and 336 deletions
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10
compiler/rustc_middle/src/mir/mod.rs
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@ -2687,8 +2687,8 @@ fn pretty_print_const_value<'tcx>(
match inner.kind() {
ty::Slice(t) => {
if *t == u8_type {
// The `inspect` here is okay since we checked the bounds, and there are
// no relocations (we have an active slice reference here). We don't use
// The `inspect` here is okay since we checked the bounds, and `u8` carries
// no provenance (we have an active slice reference here). We don't use
// this result to affect interpreter execution.
let byte_str = data
.inner()
@ -2698,8 +2698,8 @@ fn pretty_print_const_value<'tcx>(
}
}
ty::Str => {
// The `inspect` here is okay since we checked the bounds, and there are no
// relocations (we have an active `str` reference here). We don't use this
// The `inspect` here is okay since we checked the bounds, and `str` carries
// no provenance (we have an active `str` reference here). We don't use this
// result to affect interpreter execution.
let slice = data
.inner()
@ -2714,7 +2714,7 @@ fn pretty_print_const_value<'tcx>(
let n = n.kind().try_to_bits(tcx.data_layout.pointer_size).unwrap();
// cast is ok because we already checked for pointer size (32 or 64 bit) above
let range = AllocRange { start: offset, size: Size::from_bytes(n) };
let byte_str = alloc.inner().get_bytes(&tcx, range).unwrap();
let byte_str = alloc.inner().get_bytes_strip_provenance(&tcx, range).unwrap();
fmt.write_str("*")?;
pretty_print_byte_str(fmt, byte_str)?;
return Ok(());