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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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6
compiler/rustc_typeck/src/check/mod.rs
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@ -542,13 +542,13 @@ fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId) {
// For the wasm32 target statics with `#[link_section]` are placed into custom
// sections of the final output file, but this isn't link custom sections of
// other executable formats. Namely we can only embed a list of bytes,
// nothing with pointers to anything else or relocations. If any relocation
// show up, reject them here.
// nothing with provenance (pointers to anything else). If any provenance
// show up, reject it here.
// `#[link_section]` may contain arbitrary, or even undefined bytes, but it is
// the consumer's responsibility to ensure all bytes that have been read
// have defined values.
if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id())
&& alloc.inner().relocations().len() != 0
&& alloc.inner().provenance().len() != 0
{
let msg = "statics with a custom `#[link_section]` must be a \
simple list of bytes on the wasm target with no \