Add new query just for static initializers

Author: oli-obk

compiler/rustc_const_eval/src/lib.rs

@@ -40,6 +40,13 @@ pub fn provide(providers: &mut Providers) {
     const_eval::provide(providers);
     providers.eval_to_const_value_raw = const_eval::eval_to_const_value_raw_provider;
     providers.eval_to_allocation_raw = const_eval::eval_to_allocation_raw_provider;
+    providers.eval_static_initializer_raw = |tcx, def_id| {
+        assert!(tcx.is_static(def_id));
+        let instance = ty::Instance::mono(tcx, def_id);
+        let gid = rustc_middle::mir::interpret::GlobalId { instance, promoted: None };
+        let param_env = ty::ParamEnv::reveal_all();
+        Ok(tcx.eval_to_allocation_raw(param_env.and(gid))?.alloc_id)
+    };
     providers.hooks.const_caller_location = util::caller_location::const_caller_location_provider;
     providers.eval_to_valtree = |tcx, param_env_and_value| {
         let (param_env, raw) = param_env_and_value.into_parts();

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -83,6 +83,7 @@ impl Into<ErrorGuaranteed> for ReportedErrorInfo {
 TrivialTypeTraversalImpls! { ErrorHandled }
 
 pub type EvalToAllocationRawResult<'tcx> = Result<ConstAlloc<'tcx>, ErrorHandled>;
+pub type EvalStaticInitializerRawResult = Result<AllocId, ErrorHandled>;
 pub type EvalToConstValueResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;
 /// `Ok(None)` indicates the constant was fine, but the valtree couldn't be constructed.
 /// This is needed in `thir::pattern::lower_inline_const`.

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -142,11 +142,12 @@ use crate::ty::GenericArgKind;
 use crate::ty::{self, Instance, Ty, TyCtxt};
 
 pub use self::error::{
-    BadBytesAccess, CheckAlignMsg, CheckInAllocMsg, ErrorHandled, EvalToAllocationRawResult,
-    EvalToConstValueResult, EvalToValTreeResult, ExpectedKind, InterpError, InterpErrorInfo,
-    InterpResult, InvalidMetaKind, InvalidProgramInfo, MachineStopType, Misalignment, PointerKind,
-    ReportedErrorInfo, ResourceExhaustionInfo, ScalarSizeMismatch, UndefinedBehaviorInfo,
-    UnsupportedOpInfo, ValidationErrorInfo, ValidationErrorKind,
+    BadBytesAccess, CheckAlignMsg, CheckInAllocMsg, ErrorHandled, EvalStaticInitializerRawResult,
+    EvalToAllocationRawResult, EvalToConstValueResult, EvalToValTreeResult, ExpectedKind,
+    InterpError, InterpErrorInfo, InterpResult, InvalidMetaKind, InvalidProgramInfo,
+    MachineStopType, Misalignment, PointerKind, ReportedErrorInfo, ResourceExhaustionInfo,
+    ScalarSizeMismatch, UndefinedBehaviorInfo, UnsupportedOpInfo, ValidationErrorInfo,
+    ValidationErrorKind,
 };
 
 pub use self::value::Scalar;

compiler/rustc_middle/src/mir/interpret/queries.rs

@@ -194,22 +194,8 @@ impl<'tcx> TyCtxtAt<'tcx> {
     ) -> Result<mir::ConstAllocation<'tcx>, ErrorHandled> {
         trace!("eval_static_initializer: Need to compute {:?}", def_id);
         assert!(self.is_static(def_id));
-        let instance = ty::Instance::mono(*self, def_id);
-        let gid = GlobalId { instance, promoted: None };
-        self.eval_to_allocation(gid, ty::ParamEnv::reveal_all())
-    }
-
-    /// Evaluate anything constant-like, returning the allocation of the final memory.
-    ///
-    /// The span is entirely ignored here, but still helpful for better query cycle errors.
-    fn eval_to_allocation(
-        self,
-        gid: GlobalId<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-    ) -> Result<mir::ConstAllocation<'tcx>, ErrorHandled> {
-        trace!("eval_to_allocation: Need to compute {:?}", gid);
-        let raw_const = self.eval_to_allocation_raw(param_env.and(gid))?;
-        Ok(self.global_alloc(raw_const.alloc_id).unwrap_memory())
+        let alloc_id = self.eval_static_initializer_raw(def_id)?;
+        Ok(self.global_alloc(alloc_id).unwrap_memory())
     }
 }
 
@@ -237,10 +223,6 @@ impl<'tcx> TyCtxtEnsure<'tcx> {
     pub fn eval_static_initializer(self, def_id: DefId) {
         trace!("eval_static_initializer: Need to compute {:?}", def_id);
         assert!(self.tcx.is_static(def_id));
-        let instance = ty::Instance::mono(self.tcx, def_id);
-        let gid = GlobalId { instance, promoted: None };
-        let param_env = ty::ParamEnv::reveal_all();
-        trace!("eval_to_allocation: Need to compute {:?}", gid);
-        self.eval_to_allocation_raw(param_env.and(gid))
+        self.eval_static_initializer_raw(def_id);
     }
 }

compiler/rustc_middle/src/query/erase.rs

@@ -277,6 +277,7 @@ trivial! {
     rustc_middle::mir::interpret::CtfeProvenance,
     rustc_middle::mir::interpret::ErrorHandled,
     rustc_middle::mir::interpret::LitToConstError,
+    rustc_middle::mir::interpret::EvalStaticInitializerRawResult,
     rustc_middle::thir::ExprId,
     rustc_middle::traits::CodegenObligationError,
     rustc_middle::traits::EvaluationResult,

compiler/rustc_middle/src/query/mod.rs

@@ -20,7 +20,8 @@ use crate::middle::stability::{self, DeprecationEntry};
 use crate::mir;
 use crate::mir::interpret::GlobalId;
 use crate::mir::interpret::{
-    EvalToAllocationRawResult, EvalToConstValueResult, EvalToValTreeResult,
+    EvalStaticInitializerRawResult, EvalToAllocationRawResult, EvalToConstValueResult,
+    EvalToValTreeResult,
 };
 use crate::mir::interpret::{LitToConstError, LitToConstInput};
 use crate::mir::mono::CodegenUnit;
@@ -1061,7 +1062,7 @@ rustc_queries! {
 
     /// Evaluates a constant and returns the computed allocation.
     ///
-    /// **Do not use this** directly, use the `tcx.eval_static_initializer` wrapper.
+    /// **Do not use this** directly, use the `eval_to_const_value` or `eval_to_valtree` instead.
     query eval_to_allocation_raw(key: ty::ParamEnvAnd<'tcx, GlobalId<'tcx>>)
         -> EvalToAllocationRawResult<'tcx> {
         desc { |tcx|
@@ -1071,6 +1072,15 @@ rustc_queries! {
         cache_on_disk_if { true }
     }
 
+    /// Evaluate a static's initializer, returning the allocation of the initializer's memory.
+    query eval_static_initializer_raw(key: DefId) -> EvalStaticInitializerRawResult {
+        desc { |tcx|
+            "evaluating initializer of static `{}`",
+            tcx.def_path_str(key)
+        }
+        cache_on_disk_if { key.is_local() }
+    }
+
     /// Evaluates const items or anonymous constants
     /// (such as enum variant explicit discriminants or array lengths)
     /// into a representation suitable for the type system and const generics.

tests/ui/consts/recursive-zst-static.default.stderr

@@ -1,10 +1,15 @@
-error[E0391]: cycle detected when const-evaluating + checking `FOO`
+error[E0391]: cycle detected when evaluating initializer of static `FOO`
+  --> $DIR/recursive-zst-static.rs:10:1
+   |
+LL | static FOO: () = FOO;
+   | ^^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `FOO`...
   --> $DIR/recursive-zst-static.rs:10:18
    |
 LL | static FOO: () = FOO;
    |                  ^^^
-   |
-   = note: ...which immediately requires const-evaluating + checking `FOO` again
+   = note: ...which again requires evaluating initializer of static `FOO`, completing the cycle
 note: cycle used when linting top-level module
   --> $DIR/recursive-zst-static.rs:10:1
    |

tests/ui/consts/recursive-zst-static.rs

@@ -7,7 +7,7 @@
 // can depend on this fact and will thus do unsound things when it is violated.
 // See https://github.com/rust-lang/rust/issues/71078 for more details.
 
-static FOO: () = FOO; //~ cycle detected when const-evaluating + checking `FOO`
+static FOO: () = FOO; //~ cycle detected when evaluating initializer of static `FOO`
 
 fn main() {
     FOO

tests/ui/consts/recursive-zst-static.unleash.stderr

@@ -1,10 +1,15 @@
-error[E0391]: cycle detected when const-evaluating + checking `FOO`
+error[E0391]: cycle detected when evaluating initializer of static `FOO`
+  --> $DIR/recursive-zst-static.rs:10:1
+   |
+LL | static FOO: () = FOO;
+   | ^^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `FOO`...
   --> $DIR/recursive-zst-static.rs:10:18
    |
 LL | static FOO: () = FOO;
    |                  ^^^
-   |
-   = note: ...which immediately requires const-evaluating + checking `FOO` again
+   = note: ...which again requires evaluating initializer of static `FOO`, completing the cycle
 note: cycle used when linting top-level module
   --> $DIR/recursive-zst-static.rs:10:1
    |

tests/ui/consts/write-to-static-mut-in-static.stderr

@@ -4,13 +4,18 @@ error[E0080]: could not evaluate static initializer
 LL | pub static mut B: () = unsafe { A = 1; };
    |                                 ^^^^^ modifying a static's initial value from another static's initializer
 
-error[E0391]: cycle detected when const-evaluating + checking `C`
+error[E0391]: cycle detected when evaluating initializer of static `C`
+  --> $DIR/write-to-static-mut-in-static.rs:5:1
+   |
+LL | pub static mut C: u32 = unsafe { C = 1; 0 };
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires const-evaluating + checking `C`...
   --> $DIR/write-to-static-mut-in-static.rs:5:34
    |
 LL | pub static mut C: u32 = unsafe { C = 1; 0 };
    |                                  ^^^^^
-   |
-   = note: ...which immediately requires const-evaluating + checking `C` again
+   = note: ...which again requires evaluating initializer of static `C`, completing the cycle
 note: cycle used when linting top-level module
   --> $DIR/write-to-static-mut-in-static.rs:1:1
    |