Rollup merge of #126388 - RalfJung:const-eval-lint-scope, r=oli-obk

const-eval: make lint scope computation consistent

The first commit is some renaming for consistency, but otherwise unrelated. It just didn't feel worth a separate PR, but I can split this up if you prefer.

r? ``@oli-obk``

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -1,7 +1,6 @@
 use std::mem;
 
 use rustc_errors::{DiagArgName, DiagArgValue, DiagMessage, Diagnostic, IntoDiagArg};
-use rustc_hir::CRATE_HIR_ID;
 use rustc_middle::mir::interpret::{Provenance, ReportedErrorInfo};
 use rustc_middle::mir::AssertKind;
 use rustc_middle::query::TyCtxtAt;
@@ -9,7 +8,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_middle::ty::{layout::LayoutError, ConstInt};
 use rustc_span::{Span, Symbol};
 
-use super::CompileTimeInterpreter;
+use super::CompileTimeMachine;
 use crate::errors::{self, FrameNote, ReportErrorExt};
 use crate::interpret::{err_inval, err_machine_stop};
 use crate::interpret::{ErrorHandled, Frame, InterpError, InterpErrorInfo, MachineStopType};
@@ -156,11 +155,11 @@ where
     }
 }
 
-/// Emit a lint from a const-eval situation.
+/// Emit a lint from a const-eval situation, with a backtrace.
 // Even if this is unused, please don't remove it -- chances are we will need to emit a lint during const-eval again in the future!
 pub(super) fn lint<'tcx, L>(
     tcx: TyCtxtAt<'tcx>,
-    machine: &CompileTimeInterpreter<'tcx>,
+    machine: &CompileTimeMachine<'tcx>,
     lint: &'static rustc_session::lint::Lint,
     decorator: impl FnOnce(Vec<errors::FrameNote>) -> L,
 ) where
@@ -168,12 +167,5 @@ pub(super) fn lint<'tcx, L>(
 {
     let (span, frames) = get_span_and_frames(tcx, &machine.stack);
 
-    tcx.emit_node_span_lint(
-        lint,
-        // We use the root frame for this so the crate that defines the const defines whether the
-        // lint is emitted.
-        machine.stack.first().and_then(|frame| frame.lint_root()).unwrap_or(CRATE_HIR_ID),
-        span,
-        decorator(frames),
-    );
+    tcx.emit_node_span_lint(lint, machine.best_lint_scope(*tcx), span, decorator(frames));
 }

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -17,7 +17,7 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{self, Abi};
 
-use super::{CanAccessMutGlobal, CompileTimeEvalContext, CompileTimeInterpreter};
+use super::{CanAccessMutGlobal, CompileTimeInterpCx, CompileTimeMachine};
 use crate::const_eval::CheckAlignment;
 use crate::errors::ConstEvalError;
 use crate::errors::{self, DanglingPtrInFinal};
@@ -32,7 +32,7 @@ use crate::CTRL_C_RECEIVED;
 // Returns a pointer to where the result lives
 #[instrument(level = "trace", skip(ecx, body))]
 fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     cid: GlobalId<'tcx>,
     body: &'tcx mir::Body<'tcx>,
 ) -> InterpResult<'tcx, R> {
@@ -114,7 +114,7 @@ fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
             let err_diag = errors::MutablePtrInFinal { span: ecx.tcx.span, kind: intern_kind };
             ecx.tcx.emit_node_span_lint(
                 lint::builtin::CONST_EVAL_MUTABLE_PTR_IN_FINAL_VALUE,
-                ecx.best_lint_scope(),
+                ecx.machine.best_lint_scope(*ecx.tcx),
                 err_diag.span,
                 err_diag,
             )
@@ -139,13 +139,13 @@ pub(crate) fn mk_eval_cx_to_read_const_val<'tcx>(
     root_span: Span,
     param_env: ty::ParamEnv<'tcx>,
     can_access_mut_global: CanAccessMutGlobal,
-) -> CompileTimeEvalContext<'tcx> {
+) -> CompileTimeInterpCx<'tcx> {
     debug!("mk_eval_cx: {:?}", param_env);
     InterpCx::new(
         tcx,
         root_span,
         param_env,
-        CompileTimeInterpreter::new(can_access_mut_global, CheckAlignment::No),
+        CompileTimeMachine::new(can_access_mut_global, CheckAlignment::No),
     )
 }
 
@@ -156,7 +156,7 @@ pub fn mk_eval_cx_for_const_val<'tcx>(
     param_env: ty::ParamEnv<'tcx>,
     val: mir::ConstValue<'tcx>,
     ty: Ty<'tcx>,
-) -> Option<(CompileTimeEvalContext<'tcx>, OpTy<'tcx>)> {
+) -> Option<(CompileTimeInterpCx<'tcx>, OpTy<'tcx>)> {
     let ecx = mk_eval_cx_to_read_const_val(tcx.tcx, tcx.span, param_env, CanAccessMutGlobal::No);
     let op = ecx.const_val_to_op(val, ty, None).ok()?;
     Some((ecx, op))
@@ -170,7 +170,7 @@ pub fn mk_eval_cx_for_const_val<'tcx>(
 /// encounter an `Indirect` they cannot handle.
 #[instrument(skip(ecx), level = "debug")]
 pub(super) fn op_to_const<'tcx>(
-    ecx: &CompileTimeEvalContext<'tcx>,
+    ecx: &CompileTimeInterpCx<'tcx>,
     op: &OpTy<'tcx>,
     for_diagnostics: bool,
 ) -> ConstValue<'tcx> {
@@ -328,14 +328,14 @@ pub trait InterpretationResult<'tcx> {
     /// evaluation query.
     fn make_result(
         mplace: MPlaceTy<'tcx>,
-        ecx: &mut InterpCx<'tcx, CompileTimeInterpreter<'tcx>>,
+        ecx: &mut InterpCx<'tcx, CompileTimeMachine<'tcx>>,
     ) -> Self;
 }
 
 impl<'tcx> InterpretationResult<'tcx> for ConstAlloc<'tcx> {
     fn make_result(
         mplace: MPlaceTy<'tcx>,
-        _ecx: &mut InterpCx<'tcx, CompileTimeInterpreter<'tcx>>,
+        _ecx: &mut InterpCx<'tcx, CompileTimeMachine<'tcx>>,
     ) -> Self {
         ConstAlloc { alloc_id: mplace.ptr().provenance.unwrap().alloc_id(), ty: mplace.layout.ty }
     }
@@ -383,7 +383,7 @@ fn eval_in_interpreter<'tcx, R: InterpretationResult<'tcx>>(
         // they do not have to behave "as if" they were evaluated at runtime.
         // For consts however we want to ensure they behave "as if" they were evaluated at runtime,
         // so we have to reject reading mutable global memory.
-        CompileTimeInterpreter::new(CanAccessMutGlobal::from(is_static), CheckAlignment::Error),
+        CompileTimeMachine::new(CanAccessMutGlobal::from(is_static), CheckAlignment::Error),
     );
     let res = ecx.load_mir(cid.instance.def, cid.promoted);
     res.and_then(|body| eval_body_using_ecx(&mut ecx, cid, body)).map_err(|error| {
@@ -417,7 +417,7 @@ fn eval_in_interpreter<'tcx, R: InterpretationResult<'tcx>>(
 
 #[inline(always)]
 fn const_validate_mplace<'tcx>(
-    ecx: &InterpCx<'tcx, CompileTimeInterpreter<'tcx>>,
+    ecx: &InterpCx<'tcx, CompileTimeMachine<'tcx>>,
     mplace: &MPlaceTy<'tcx>,
     cid: GlobalId<'tcx>,
 ) -> Result<(), ErrorHandled> {
@@ -447,7 +447,7 @@ fn const_validate_mplace<'tcx>(
 
 #[inline(always)]
 fn report_validation_error<'tcx>(
-    ecx: &InterpCx<'tcx, CompileTimeInterpreter<'tcx>>,
+    ecx: &InterpCx<'tcx, CompileTimeMachine<'tcx>>,
     error: InterpErrorInfo<'tcx>,
     alloc_id: AllocId,
 ) -> ErrorHandled {

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -9,12 +9,13 @@ use rustc_data_structures::fx::IndexEntry;
 use rustc_hir::def_id::DefId;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::LangItem;
+use rustc_hir::{self as hir, CRATE_HIR_ID};
 use rustc_middle::bug;
 use rustc_middle::mir;
 use rustc_middle::mir::AssertMessage;
 use rustc_middle::query::TyCtxtAt;
-use rustc_middle::ty;
 use rustc_middle::ty::layout::{FnAbiOf, TyAndLayout};
+use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint::builtin::WRITES_THROUGH_IMMUTABLE_POINTER;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
@@ -44,7 +45,7 @@ const TINY_LINT_TERMINATOR_LIMIT: usize = 20;
 const PROGRESS_INDICATOR_START: usize = 4_000_000;
 
 /// Extra machine state for CTFE, and the Machine instance
-pub struct CompileTimeInterpreter<'tcx> {
+pub struct CompileTimeMachine<'tcx> {
     /// The number of terminators that have been evaluated.
     ///
     /// This is used to produce lints informing the user that the compiler is not stuck.
@@ -89,12 +90,12 @@ impl From<bool> for CanAccessMutGlobal {
     }
 }
 
-impl<'tcx> CompileTimeInterpreter<'tcx> {
+impl<'tcx> CompileTimeMachine<'tcx> {
     pub(crate) fn new(
         can_access_mut_global: CanAccessMutGlobal,
         check_alignment: CheckAlignment,
     ) -> Self {
-        CompileTimeInterpreter {
+        CompileTimeMachine {
             num_evaluated_steps: 0,
             stack: Vec::new(),
             can_access_mut_global,
@@ -163,7 +164,7 @@ impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxIndexMap<K, V> {
     }
 }
 
-pub(crate) type CompileTimeEvalContext<'tcx> = InterpCx<'tcx, CompileTimeInterpreter<'tcx>>;
+pub(crate) type CompileTimeInterpCx<'tcx> = InterpCx<'tcx, CompileTimeMachine<'tcx>>;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum MemoryKind {
@@ -195,7 +196,7 @@ impl interpret::MayLeak for ! {
     }
 }
 
-impl<'tcx> CompileTimeEvalContext<'tcx> {
+impl<'tcx> CompileTimeInterpCx<'tcx> {
     fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
         let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
         let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
@@ -369,7 +370,16 @@ impl<'tcx> CompileTimeEvalContext<'tcx> {
     }
 }
 
-impl<'tcx> interpret::Machine<'tcx> for CompileTimeInterpreter<'tcx> {
+impl<'tcx> CompileTimeMachine<'tcx> {
+    #[inline(always)]
+    /// Find the first stack frame that is within the current crate, if any.
+    /// Otherwise, return the crate's HirId
+    pub fn best_lint_scope(&self, tcx: TyCtxt<'tcx>) -> hir::HirId {
+        self.stack.iter().find_map(|frame| frame.lint_root(tcx)).unwrap_or(CRATE_HIR_ID)
+    }
+}
+
+impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
     compile_time_machine!(<'tcx>);
 
     type MemoryKind = MemoryKind;
@@ -600,7 +610,7 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeInterpreter<'tcx> {
                 // By default, we stop after a million steps, but the user can disable this lint
                 // to be able to run until the heat death of the universe or power loss, whichever
                 // comes first.
-                let hir_id = ecx.best_lint_scope();
+                let hir_id = ecx.machine.best_lint_scope(*ecx.tcx);
                 let is_error = ecx
                     .tcx
                     .lint_level_at_node(

compiler/rustc_const_eval/src/const_eval/valtrees.rs

@@ -9,7 +9,7 @@ use rustc_target::abi::{Abi, VariantIdx};
 use tracing::{debug, instrument, trace};
 
 use super::eval_queries::{mk_eval_cx_to_read_const_val, op_to_const};
-use super::machine::CompileTimeEvalContext;
+use super::machine::CompileTimeInterpCx;
 use super::{ValTreeCreationError, ValTreeCreationResult, VALTREE_MAX_NODES};
 use crate::const_eval::CanAccessMutGlobal;
 use crate::errors::MaxNumNodesInConstErr;
@@ -21,7 +21,7 @@ use crate::interpret::{
 
 #[instrument(skip(ecx), level = "debug")]
 fn branches<'tcx>(
-    ecx: &CompileTimeEvalContext<'tcx>,
+    ecx: &CompileTimeInterpCx<'tcx>,
     place: &MPlaceTy<'tcx>,
     n: usize,
     variant: Option<VariantIdx>,
@@ -59,7 +59,7 @@ fn branches<'tcx>(
 
 #[instrument(skip(ecx), level = "debug")]
 fn slice_branches<'tcx>(
-    ecx: &CompileTimeEvalContext<'tcx>,
+    ecx: &CompileTimeInterpCx<'tcx>,
     place: &MPlaceTy<'tcx>,
     num_nodes: &mut usize,
 ) -> ValTreeCreationResult<'tcx> {
@@ -77,7 +77,7 @@ fn slice_branches<'tcx>(
 
 #[instrument(skip(ecx), level = "debug")]
 fn const_to_valtree_inner<'tcx>(
-    ecx: &CompileTimeEvalContext<'tcx>,
+    ecx: &CompileTimeInterpCx<'tcx>,
     place: &MPlaceTy<'tcx>,
     num_nodes: &mut usize,
 ) -> ValTreeCreationResult<'tcx> {
@@ -219,7 +219,7 @@ fn reconstruct_place_meta<'tcx>(
 
 #[instrument(skip(ecx), level = "debug", ret)]
 fn create_valtree_place<'tcx>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     layout: TyAndLayout<'tcx>,
     valtree: ty::ValTree<'tcx>,
 ) -> MPlaceTy<'tcx> {
@@ -364,7 +364,7 @@ pub fn valtree_to_const_value<'tcx>(
 
 /// Put a valtree into memory and return a reference to that.
 fn valtree_to_ref<'tcx>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     valtree: ty::ValTree<'tcx>,
     pointee_ty: Ty<'tcx>,
 ) -> Immediate {
@@ -380,7 +380,7 @@ fn valtree_to_ref<'tcx>(
 
 #[instrument(skip(ecx), level = "debug")]
 fn valtree_into_mplace<'tcx>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     place: &MPlaceTy<'tcx>,
     valtree: ty::ValTree<'tcx>,
 ) {
@@ -457,6 +457,6 @@ fn valtree_into_mplace<'tcx>(
     }
 }
 
-fn dump_place<'tcx>(ecx: &CompileTimeEvalContext<'tcx>, place: &MPlaceTy<'tcx>) {
+fn dump_place<'tcx>(ecx: &CompileTimeInterpCx<'tcx>, place: &MPlaceTy<'tcx>) {
     trace!("{:?}", ecx.dump_place(&PlaceTy::from(place.clone())));
 }

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -4,7 +4,6 @@ use std::{fmt, mem};
 use either::{Either, Left, Right};
 use tracing::{debug, info, info_span, instrument, trace};
 
-use hir::CRATE_HIR_ID;
 use rustc_errors::DiagCtxt;
 use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
 use rustc_index::IndexVec;
@@ -271,13 +270,18 @@ impl<'tcx, Prov: Provenance, Extra> Frame<'tcx, Prov, Extra> {
         }
     }
 
-    pub fn lint_root(&self) -> Option<hir::HirId> {
-        self.current_source_info().and_then(|source_info| {
-            match &self.body.source_scopes[source_info.scope].local_data {
+    pub fn lint_root(&self, tcx: TyCtxt<'tcx>) -> Option<hir::HirId> {
+        // We first try to get a HirId via the current source scope,
+        // and fall back to `body.source`.
+        self.current_source_info()
+            .and_then(|source_info| match &self.body.source_scopes[source_info.scope].local_data {
                 mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
                 mir::ClearCrossCrate::Clear => None,
-            }
-        })
+            })
+            .or_else(|| {
+                let def_id = self.body.source.def_id().as_local();
+                def_id.map(|def_id| tcx.local_def_id_to_hir_id(def_id))
+            })
     }
 
     /// Returns the address of the buffer where the locals are stored. This is used by `Place` as a
@@ -509,17 +513,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         self.stack().last().map_or(self.tcx.span, |f| f.current_span())
     }
 
-    /// Find the first stack frame that is within the current crate, if any;
-    /// otherwise return the crate's HirId.
-    #[inline(always)]
-    pub fn best_lint_scope(&self) -> hir::HirId {
-        self.stack()
-            .iter()
-            .find_map(|frame| frame.body.source.def_id().as_local())
-            .map_or(CRATE_HIR_ID, |def_id| self.tcx.local_def_id_to_hir_id(def_id))
-    }
-
-    #[inline(always)]
     pub(crate) fn stack(&self) -> &[Frame<'tcx, M::Provenance, M::FrameExtra>] {
         M::stack(self)
     }

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -45,7 +45,7 @@ pub trait HasStaticRootDefId {
     fn static_def_id(&self) -> Option<LocalDefId>;
 }
 
-impl HasStaticRootDefId for const_eval::CompileTimeInterpreter<'_> {
+impl HasStaticRootDefId for const_eval::CompileTimeMachine<'_> {
     fn static_def_id(&self) -> Option<LocalDefId> {
         Some(self.static_root_ids?.1)
     }

compiler/rustc_const_eval/src/interpret/util.rs

@@ -1,4 +1,4 @@
-use crate::const_eval::{CompileTimeEvalContext, CompileTimeInterpreter, InterpretationResult};
+use crate::const_eval::{CompileTimeInterpCx, CompileTimeMachine, InterpretationResult};
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{Allocation, InterpResult, Pointer};
@@ -84,7 +84,7 @@ where
 impl<'tcx> InterpretationResult<'tcx> for mir::interpret::ConstAllocation<'tcx> {
     fn make_result(
         mplace: MPlaceTy<'tcx>,
-        ecx: &mut InterpCx<'tcx, CompileTimeInterpreter<'tcx>>,
+        ecx: &mut InterpCx<'tcx, CompileTimeMachine<'tcx>>,
     ) -> Self {
         let alloc_id = mplace.ptr().provenance.unwrap().alloc_id();
         let alloc = ecx.memory.alloc_map.swap_remove(&alloc_id).unwrap().1;
@@ -93,7 +93,7 @@ impl<'tcx> InterpretationResult<'tcx> for mir::interpret::ConstAllocation<'tcx>
 }
 
 pub(crate) fn create_static_alloc<'tcx>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     static_def_id: LocalDefId,
     layout: TyAndLayout<'tcx>,
 ) -> InterpResult<'tcx, MPlaceTy<'tcx>> {

compiler/rustc_const_eval/src/util/caller_location.rs

@@ -7,12 +7,12 @@ use rustc_middle::ty::{self, Mutability};
 use rustc_span::symbol::Symbol;
 use tracing::trace;
 
-use crate::const_eval::{mk_eval_cx_to_read_const_val, CanAccessMutGlobal, CompileTimeEvalContext};
+use crate::const_eval::{mk_eval_cx_to_read_const_val, CanAccessMutGlobal, CompileTimeInterpCx};
 use crate::interpret::*;
 
 /// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.
 fn alloc_caller_location<'tcx>(
-    ecx: &mut CompileTimeEvalContext<'tcx>,
+    ecx: &mut CompileTimeInterpCx<'tcx>,
     filename: Symbol,
     line: u32,
     col: u32,

compiler/rustc_const_eval/src/util/check_validity_requirement.rs

@@ -3,7 +3,7 @@ use rustc_middle::ty::layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout, Val
 use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_target::abi::{Abi, FieldsShape, Scalar, Variants};
 
-use crate::const_eval::{CanAccessMutGlobal, CheckAlignment, CompileTimeInterpreter};
+use crate::const_eval::{CanAccessMutGlobal, CheckAlignment, CompileTimeMachine};
 use crate::interpret::{InterpCx, MemoryKind, OpTy};
 
 /// Determines if this type permits "raw" initialization by just transmuting some memory into an
@@ -45,7 +45,7 @@ fn might_permit_raw_init_strict<'tcx>(
     tcx: TyCtxt<'tcx>,
     kind: ValidityRequirement,
 ) -> Result<bool, &'tcx LayoutError<'tcx>> {
-    let machine = CompileTimeInterpreter::new(CanAccessMutGlobal::No, CheckAlignment::Error);
+    let machine = CompileTimeMachine::new(CanAccessMutGlobal::No, CheckAlignment::Error);
 
     let mut cx = InterpCx::new(tcx, rustc_span::DUMMY_SP, ParamEnv::reveal_all(), machine);