Tracking issue for banning field projecting into `[rustc_layout_scalar_valid_range_*]` types (MCP807)

[scottmcm]

For rust-lang/compiler-team#807

Steps:

• Update the standard library to stop doing this
  • Update NonZero and NonNull to not field-project (per MCP#807) #133651
  • Update a bunch of library types for MCP807 #135236
  • …
• Update the compiler to stop doing this

  • rust/compiler/rustc_mir_transform/src/elaborate_box_derefs.rs

    Line 37 in 490b2cc

    PlaceElem::Field(FieldIdx::ZERO, ptr_ty),

  • Transmute from NonNull to pointer when elaborating a box deref (MCP807) #135182
  • Don't project into NonNull when dropping a Box #137112
  • …
• Add MIR-opts for any new patterns that show up from doing this
  • [mir-opt] GVN some more transmute cases #133324
  • …
• Ban it in the MIR validator
  • …
• Update MIR-opts to be more willing to merge projections and such
  • sroa::escaping_locals can stop looking at layout, for example
  • …

SEO: rustc_layout_scalar_valid_range_start rustc_layout_scalar_valid_range_end NonZero NonNull "pattern types".