rust-lang · bors · Feb 10, 2025 · Jan 24, 2025 · RalfJung · Feb 2, 2025
diff --git a/Cargo.lock b/Cargo.lock
@@ -1209,16 +1209,6 @@ dependencies = [
 "tidy",
 ]

-[[package]]
-name = "field-offset"
-version = "0.3.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "38e2275cc4e4fc009b0669731a1e5ab7ebf11f469eaede2bab9309a5b4d6057f"
-dependencies = [
- "memoffset",
- "rustc_version",
-]
-
 [[package]]
 name = "filetime"
 version = "0.2.25"
@@ -2295,15 +2285,6 @@ dependencies = [
 "libc",
 ]

-[[package]]
-name = "memoffset"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "488016bfae457b036d996092f6cb448677611ce4449e970ceaf42695203f218a"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "mime"
 version = "0.3.17"
@@ -4176,7 +4157,6 @@ version = "0.0.0"
 dependencies = [
 "bitflags",
 "either",
- "field-offset",
 "gsgdt",
 "polonius-engine",
 "rustc-rayon-core",
@@ -4424,7 +4404,6 @@ dependencies = [
 name = "rustc_query_impl"
 version = "0.0.0"
 dependencies = [
- "field-offset",
 "measureme",
 "rustc_data_structures",
 "rustc_errors",

diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
@@ -7,7 +7,6 @@ edition = "2021"
 # tidy-alphabetical-start
 bitflags = "2.4.1"
 either = "1.5.0"
-field-offset = "0.3.5"
 gsgdt = "0.1.2"
 polonius-engine = "0.13.0"
 rustc-rayon-core = { version = "0.5.0" }

diff --git a/compiler/rustc_middle/src/query/plumbing.rs b/compiler/rustc_middle/src/query/plumbing.rs
@@ -1,6 +1,5 @@
 use std::ops::Deref;

-use field_offset::FieldOffset;
 use rustc_data_structures::sync::{AtomicU64, WorkerLocal};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::hir_id::OwnerId;
@@ -24,8 +23,10 @@ pub struct DynamicQuery<'tcx, C: QueryCache> {
    pub eval_always: bool,
    pub dep_kind: DepKind,
    pub handle_cycle_error: HandleCycleError,
-    pub query_state: FieldOffset<QueryStates<'tcx>, QueryState<C::Key>>,
-    pub query_cache: FieldOffset<QueryCaches<'tcx>, C>,
+    // Offset of this query's state field in the QueryStates struct
+    pub query_state: usize,
+    // Offset of this query's cache field in the QueryCaches struct
+    pub query_cache: usize,
    pub cache_on_disk: fn(tcx: TyCtxt<'tcx>, key: &C::Key) -> bool,
    pub execute_query: fn(tcx: TyCtxt<'tcx>, k: C::Key) -> C::Value,
    pub compute: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> C::Value,

diff --git a/compiler/rustc_query_impl/Cargo.toml b/compiler/rustc_query_impl/Cargo.toml
@@ -5,7 +5,6 @@ edition = "2021"

 [dependencies]
 # tidy-alphabetical-start
-field-offset = "0.3.5"
 measureme = "11"
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }

diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
@@ -11,7 +11,6 @@
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end

-use field_offset::offset_of;
 use rustc_data_structures::stable_hasher::HashStable;
 use rustc_data_structures::sync::AtomicU64;
 use rustc_middle::arena::Arena;
@@ -89,15 +88,27 @@ where
    where
        QueryCtxt<'tcx>: 'a,
    {
-        self.dynamic.query_state.apply(&qcx.tcx.query_system.states)
+        // Safety:
+        // This is just manually doing the subfield referencing through pointer math.
+        unsafe {
+            &*(&qcx.tcx.query_system.states as *const QueryStates<'tcx>)
+                .byte_add(self.dynamic.query_state)
+                .cast::<QueryState<Self::Key>>()
+        }
    }

    #[inline(always)]
    fn query_cache<'a>(self, qcx: QueryCtxt<'tcx>) -> &'a Self::Cache
    where
        'tcx: 'a,
    {
-        self.dynamic.query_cache.apply(&qcx.tcx.query_system.caches)
+        // Safety:
+        // This is just manually doing the subfield referencing through pointer math.
+        unsafe {
+            &*(&qcx.tcx.query_system.caches as *const QueryCaches<'tcx>)
+                .byte_add(self.dynamic.query_cache)
+                .cast::<Self::Cache>()
+        }
    }

    #[inline(always)]

diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
@@ -605,8 +605,8 @@ macro_rules! define_queries {
                    eval_always: is_eval_always!([$($modifiers)*]),
                    dep_kind: dep_graph::dep_kinds::$name,
                    handle_cycle_error: handle_cycle_error!([$($modifiers)*]),
-                    query_state: offset_of!(QueryStates<'tcx> => $name),
-                    query_cache: offset_of!(QueryCaches<'tcx> => $name),
+                    query_state: std::mem::offset_of!(QueryStates<'tcx>, $name),
+                    query_cache: std::mem::offset_of!(QueryCaches<'tcx>, $name),
                    cache_on_disk: |tcx, key| ::rustc_middle::query::cached::$name(tcx, key),
                    execute_query: |tcx, key| erase(tcx.$name(key)),
                    compute: |tcx, key| {

diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
@@ -285,7 +285,6 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
    "expect-test",
    "fallible-iterator", // dependency of `thorin`
    "fastrand",
-    "field-offset",
    "flate2",
    "fluent-bundle",
    "fluent-langneg",
@@ -327,7 +326,6 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
    "measureme",
    "memchr",
    "memmap2",
-    "memoffset",
    "miniz_oxide",
    "nix",
    "nu-ansi-term",
@@ -367,14 +365,12 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
    "rustc-rayon-core",
    "rustc-stable-hash",
    "rustc_apfloat",
-    "rustc_version",
    "rustix",
    "ruzstd", // via object in thorin-dwp
    "ryu",
    "scoped-tls",
    "scopeguard",
    "self_cell",
-    "semver",
    "serde",
    "serde_derive",
    "serde_json",
-Original file line number
+Diff line change
@@ -1,6 +1,5 @@
     use std::ops::Deref;
-    use field_offset::FieldOffset;
     use rustc_data_structures::sync::{AtomicU64, WorkerLocal};
     use rustc_hir::def_id::{DefId, LocalDefId};
     use rustc_hir::hir_id::OwnerId;
@@ -24,8 +23,10 @@ pub struct DynamicQuery<'tcx, C: QueryCache> {
         pub eval_always: bool,
         pub dep_kind: DepKind,
         pub handle_cycle_error: HandleCycleError,
-        pub query_state: FieldOffset<QueryStates<'tcx>, QueryState<C::Key>>,
-        pub query_cache: FieldOffset<QueryCaches<'tcx>, C>,
+        // Offset of this query's state field in the QueryStates struct
+        pub query_state: usize,
+        // Offset of this query's cache field in the QueryCaches struct
+        pub query_cache: usize,
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            RalfJung
  

      

      

      


        Feb 2, 2025


      
    

  


        
      
  
  
  
    

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      Please add comments explaining the meaning of these fields. Currently that seems quite tricky to figure out.
    
  
  


    

        
      
  
  
    
  
  
  
    
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            davidv1992
  

      

      

      


        Feb 3, 2025


      
    

  


        
      
  
  
  
    

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      Added the comments
    
  
  


    

        
      
  
  
    
  
  
  
    
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         pub cache_on_disk: fn(tcx: TyCtxt<'tcx>, key: &C::Key) -> bool,
         pub execute_query: fn(tcx: TyCtxt<'tcx>, k: C::Key) -> C::Value,
         pub compute: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> C::Value,
-          Expand Down