Rollup merge of #142103 - scottmcm:fieldidx-in-interp, r=oli-obk

Update `InterpCx::project_field` to take `FieldIdx`

As suggested by Ralf in https://github.com/rust-lang/rust/pull/142005#discussion_r2125839015

7 files changed, 30 insertions, 24 deletions

diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs
index 8fe034d2582..5880e5fbc37 100644
--- a/src/tools/miri/src/eval.rs
+++ b/src/tools/miri/src/eval.rs
@@ -359,8 +359,8 @@ pub fn create_ecx<'tcx>(
         let argvs_layout =
             ecx.layout_of(Ty::new_array(tcx, u8_ptr_type, u64::try_from(argvs.len()).unwrap()))?;
         let argvs_place = ecx.allocate(argvs_layout, MiriMemoryKind::Machine.into())?;
-        for (idx, arg) in argvs.into_iter().enumerate() {
-            let place = ecx.project_field(&argvs_place, idx)?;
+        for (arg, idx) in argvs.into_iter().zip(0..) {
+            let place = ecx.project_index(&argvs_place, idx)?;
             ecx.write_immediate(arg, &place)?;
         }
         ecx.mark_immutable(&argvs_place);
@@ -389,8 +389,8 @@ pub fn create_ecx<'tcx>(
                 ecx.allocate(ecx.layout_of(cmd_type)?, MiriMemoryKind::Machine.into())?;
             ecx.machine.cmd_line = Some(cmd_place.ptr());
             // Store the UTF-16 string. We just allocated so we know the bounds are fine.
-            for (idx, &c) in cmd_utf16.iter().enumerate() {
-                let place = ecx.project_field(&cmd_place, idx)?;
+            for (&c, idx) in cmd_utf16.iter().zip(0..) {
+                let place = ecx.project_index(&cmd_place, idx)?;
                 ecx.write_scalar(Scalar::from_u16(c), &place)?;
             }
             ecx.mark_immutable(&cmd_place);
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index 20ea239b7e5..4edecc864dd 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -326,7 +326,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     ) -> InterpResult<'tcx, Option<P>> {
         let this = self.eval_context_ref();
         let adt = base.layout().ty.ty_adt_def().unwrap();
-        for (idx, field) in adt.non_enum_variant().fields.iter().enumerate() {
+        for (idx, field) in adt.non_enum_variant().fields.iter_enumerated() {
             if field.name.as_str() == name {
                 return interp_ok(Some(this.project_field(base, idx)?));
             }
@@ -376,6 +376,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
         for (idx, &val) in values.iter().enumerate() {
+            let idx = FieldIdx::from_usize(idx);
             let field = this.project_field(dest, idx)?;
             this.write_int(val, &field)?;
         }
@@ -763,10 +764,10 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     /// `EINVAL` in this case.
     fn read_timespec(&mut self, tp: &MPlaceTy<'tcx>) -> InterpResult<'tcx, Option<Duration>> {
         let this = self.eval_context_mut();
-        let seconds_place = this.project_field(tp, 0)?;
+        let seconds_place = this.project_field(tp, FieldIdx::ZERO)?;
         let seconds_scalar = this.read_scalar(&seconds_place)?;
         let seconds = seconds_scalar.to_target_isize(this)?;
-        let nanoseconds_place = this.project_field(tp, 1)?;
+        let nanoseconds_place = this.project_field(tp, FieldIdx::ONE)?;
         let nanoseconds_scalar = this.read_scalar(&nanoseconds_place)?;
         let nanoseconds = nanoseconds_scalar.to_target_isize(this)?;
 
diff --git a/src/tools/miri/src/shims/backtrace.rs b/src/tools/miri/src/shims/backtrace.rs
index ab11553df63..8606735c913 100644
--- a/src/tools/miri/src/shims/backtrace.rs
+++ b/src/tools/miri/src/shims/backtrace.rs
@@ -1,4 +1,4 @@
-use rustc_abi::{CanonAbi, Size};
+use rustc_abi::{CanonAbi, FieldIdx, Size};
 use rustc_middle::ty::layout::LayoutOf as _;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_span::{BytePos, Loc, Symbol, hygiene};
@@ -159,23 +159,23 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             1 => {
                 this.write_scalar(
                     Scalar::from_target_usize(name.len().to_u64(), this),
-                    &this.project_field(dest, 0)?,
+                    &this.project_field(dest, FieldIdx::from_u32(0))?,
                 )?;
                 this.write_scalar(
                     Scalar::from_target_usize(filename.len().to_u64(), this),
-                    &this.project_field(dest, 1)?,
+                    &this.project_field(dest, FieldIdx::from_u32(1))?,
                 )?;
             }
             _ => throw_unsup_format!("unknown `miri_resolve_frame` flags {}", flags),
         }
 
-        this.write_scalar(Scalar::from_u32(lineno), &this.project_field(dest, 2)?)?;
-        this.write_scalar(Scalar::from_u32(colno), &this.project_field(dest, 3)?)?;
+        this.write_scalar(Scalar::from_u32(lineno), &this.project_field(dest, FieldIdx::from_u32(2))?)?;
+        this.write_scalar(Scalar::from_u32(colno), &this.project_field(dest, FieldIdx::from_u32(3))?)?;
 
         // Support a 4-field struct for now - this is deprecated
         // and slated for removal.
         if num_fields == 5 {
-            this.write_pointer(fn_ptr, &this.project_field(dest, 4)?)?;
+            this.write_pointer(fn_ptr, &this.project_field(dest, FieldIdx::from_u32(4))?)?;
         }
 
         interp_ok(())
diff --git a/src/tools/miri/src/shims/unix/env.rs b/src/tools/miri/src/shims/unix/env.rs
index aebb5757aec..62ac7ee3806 100644
--- a/src/tools/miri/src/shims/unix/env.rs
+++ b/src/tools/miri/src/shims/unix/env.rs
@@ -2,8 +2,9 @@ use std::ffi::{OsStr, OsString};
 use std::io::ErrorKind;
 use std::{env, mem};
 
-use rustc_abi::Size;
+use rustc_abi::{FieldIdx, Size};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_index::IndexVec;
 use rustc_middle::ty::Ty;
 use rustc_middle::ty::layout::LayoutOf;
 
@@ -118,7 +119,7 @@ fn alloc_env_var<'tcx>(
 /// Allocates an `environ` block with the given list of pointers.
 fn alloc_environ_block<'tcx>(
     ecx: &mut InterpCx<'tcx, MiriMachine<'tcx>>,
-    mut vars: Vec<Pointer>,
+    mut vars: IndexVec<FieldIdx, Pointer>,
 ) -> InterpResult<'tcx, Pointer> {
     // Add trailing null.
     vars.push(Pointer::null());
@@ -129,7 +130,7 @@ fn alloc_environ_block<'tcx>(
         u64::try_from(vars.len()).unwrap(),
     ))?;
     let vars_place = ecx.allocate(vars_layout, MiriMemoryKind::Runtime.into())?;
-    for (idx, var) in vars.into_iter().enumerate() {
+    for (idx, var) in vars.into_iter_enumerated() {
         let place = ecx.project_field(&vars_place, idx)?;
         ecx.write_pointer(var, &place)?;
     }
diff --git a/src/tools/miri/src/shims/unix/freebsd/sync.rs b/src/tools/miri/src/shims/unix/freebsd/sync.rs
index 54650f35b2c..f4e7d9e58f9 100644
--- a/src/tools/miri/src/shims/unix/freebsd/sync.rs
+++ b/src/tools/miri/src/shims/unix/freebsd/sync.rs
@@ -2,6 +2,8 @@
 
 use core::time::Duration;
 
+use rustc_abi::FieldIdx;
+
 use crate::concurrency::sync::FutexRef;
 use crate::*;
 
@@ -214,18 +216,18 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // Only flag allowed is UMTX_ABSTIME.
         let abs_time = this.eval_libc_u32("UMTX_ABSTIME");
 
-        let timespec_place = this.project_field(ut, 0)?;
+        let timespec_place = this.project_field(ut, FieldIdx::from_u32(0))?;
         // Inner `timespec` must still be valid.
         let duration = match this.read_timespec(&timespec_place)? {
             Some(dur) => dur,
             None => return interp_ok(None),
         };
 
-        let flags_place = this.project_field(ut, 1)?;
+        let flags_place = this.project_field(ut, FieldIdx::from_u32(1))?;
         let flags = this.read_scalar(&flags_place)?.to_u32()?;
         let abs_time_flag = flags == abs_time;
 
-        let clock_id_place = this.project_field(ut, 2)?;
+        let clock_id_place = this.project_field(ut, FieldIdx::from_u32(2))?;
         let clock_id = this.read_scalar(&clock_id_place)?.to_i32()?;
         let timeout_clock = this.translate_umtx_time_clock_id(clock_id)?;
 
diff --git a/src/tools/miri/src/shims/unix/linux_like/epoll.rs b/src/tools/miri/src/shims/unix/linux_like/epoll.rs
index b489595b4cd..f971fb10b19 100644
--- a/src/tools/miri/src/shims/unix/linux_like/epoll.rs
+++ b/src/tools/miri/src/shims/unix/linux_like/epoll.rs
@@ -4,6 +4,8 @@ use std::io;
 use std::rc::{Rc, Weak};
 use std::time::Duration;
 
+use rustc_abi::FieldIdx;
+
 use crate::concurrency::VClock;
 use crate::shims::files::{
     DynFileDescriptionRef, FdId, FileDescription, FileDescriptionRef, WeakFileDescriptionRef,
@@ -284,8 +286,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
         if op == epoll_ctl_add || op == epoll_ctl_mod {
             // Read event bitmask and data from epoll_event passed by caller.
-            let mut events = this.read_scalar(&this.project_field(&event, 0)?)?.to_u32()?;
-            let data = this.read_scalar(&this.project_field(&event, 1)?)?.to_u64()?;
+            let mut events = this.read_scalar(&this.project_field(&event, FieldIdx::ZERO)?)?.to_u32()?;
+            let data = this.read_scalar(&this.project_field(&event, FieldIdx::ONE)?)?.to_u64()?;
 
             // Unset the flag we support to discover if any unsupported flags are used.
             let mut flags = events;
diff --git a/src/tools/miri/src/shims/x86/mod.rs b/src/tools/miri/src/shims/x86/mod.rs
index 7dee8ddd23c..1e82f521249 100644
--- a/src/tools/miri/src/shims/x86/mod.rs
+++ b/src/tools/miri/src/shims/x86/mod.rs
@@ -1,4 +1,4 @@
-use rustc_abi::{CanonAbi, Size};
+use rustc_abi::{CanonAbi, FieldIdx, Size};
 use rustc_apfloat::Float;
 use rustc_apfloat::ieee::Single;
 use rustc_middle::ty::Ty;
@@ -54,8 +54,8 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 };
 
                 let (sum, cb_out) = carrying_add(this, cb_in, a, b, op)?;
-                this.write_scalar(cb_out, &this.project_field(dest, 0)?)?;
-                this.write_immediate(*sum, &this.project_field(dest, 1)?)?;
+                this.write_scalar(cb_out, &this.project_field(dest, FieldIdx::ZERO)?)?;
+                this.write_immediate(*sum, &this.project_field(dest, FieldIdx::ONE)?)?;
             }
 
             // Used to implement the `_addcarryx_u{32, 64}` functions. They are semantically identical with the `_addcarry_u{32, 64}` functions,