Rollup merge of #104647 - RalfJung:alloc-strict-provenance, r=thomcc

enable fuzzy_provenance_casts lint in liballoc and libstd

r? ````@thomcc````

library/std/src/lib.rs

@@ -220,6 +220,7 @@
 #![allow(explicit_outlives_requirements)]
 #![allow(unused_lifetimes)]
 #![deny(rustc::existing_doc_keyword)]
+#![deny(fuzzy_provenance_casts)]
 // Ensure that std can be linked against panic_abort despite compiled with `-C panic=unwind`
 #![deny(ffi_unwind_calls)]
 // std may use features in a platform-specific way
@@ -598,7 +599,7 @@ mod panicking;
 mod personality;
 
 #[path = "../../backtrace/src/lib.rs"]
-#[allow(dead_code, unused_attributes)]
+#[allow(dead_code, unused_attributes, fuzzy_provenance_casts)]
 mod backtrace_rs;
 
 // Re-export macros defined in libcore.

library/std/src/os/windows/io/socket.rs

@@ -90,6 +90,7 @@ impl OwnedSocket {
     }
 
     // FIXME(strict_provenance_magic): we defined RawSocket to be a u64 ;-;
+    #[allow(fuzzy_provenance_casts)]
     #[cfg(not(target_vendor = "uwp"))]
     pub(crate) fn set_no_inherit(&self) -> io::Result<()> {
         cvt(unsafe {

library/std/src/personality/dwarf/eh.rs

@@ -13,6 +13,7 @@
 
 use super::DwarfReader;
 use core::mem;
+use core::ptr;
 
 pub const DW_EH_PE_omit: u8 = 0xFF;
 pub const DW_EH_PE_absptr: u8 = 0x00;
@@ -151,7 +152,7 @@ unsafe fn read_encoded_pointer(
 
     // DW_EH_PE_aligned implies it's an absolute pointer value
     if encoding == DW_EH_PE_aligned {
-        reader.ptr = round_up(reader.ptr as usize, mem::size_of::<usize>())? as *const u8;
+        reader.ptr = reader.ptr.with_addr(round_up(reader.ptr.addr(), mem::size_of::<usize>())?);
         return Ok(reader.read::<usize>());
     }
 
@@ -171,7 +172,7 @@ unsafe fn read_encoded_pointer(
     result += match encoding & 0x70 {
         DW_EH_PE_absptr => 0,
         // relative to address of the encoded value, despite the name
-        DW_EH_PE_pcrel => reader.ptr as usize,
+        DW_EH_PE_pcrel => reader.ptr.expose_addr(),
         DW_EH_PE_funcrel => {
             if context.func_start == 0 {
                 return Err(());
@@ -184,7 +185,7 @@ unsafe fn read_encoded_pointer(
     };
 
     if encoding & DW_EH_PE_indirect != 0 {
-        result = *(result as *const usize);
+        result = *ptr::from_exposed_addr::<usize>(result);
     }
 
     Ok(result)

library/std/src/sys/sgx/mod.rs

@@ -3,6 +3,7 @@
 //! This module contains the facade (aka platform-specific) implementations of
 //! OS level functionality for Fortanix SGX.
 #![deny(unsafe_op_in_unsafe_fn)]
+#![allow(fuzzy_provenance_casts)] // FIXME: this entire module systematically confuses pointers and integers
 
 use crate::io::ErrorKind;
 use crate::sync::atomic::{AtomicBool, Ordering};