Exclude mir::coverage types from TypeFoldable/TypeVisitable

These types are unlikely to ever contain type information in the foreseeable
future, so excluding them from TypeFoldable/TypeVisitable avoids some unhelpful
derive boilerplate.

Author: Zalathar

compiler/rustc_middle/src/mir/coverage.rs

@@ -4,7 +4,7 @@ use std::fmt::{self, Debug, Formatter};
 
 use rustc_index::IndexVec;
 use rustc_index::bit_set::DenseBitSet;
-use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
+use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_span::Span;
 
 rustc_index::newtype_index! {
@@ -72,7 +72,7 @@ impl ConditionId {
 /// Enum that can hold a constant zero value, the ID of an physical coverage
 /// counter, or the ID of a coverage-counter expression.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub enum CovTerm {
     Zero,
     Counter(CounterId),
@@ -89,7 +89,7 @@ impl Debug for CovTerm {
     }
 }
 
-#[derive(Clone, PartialEq, TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(Clone, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)]
 pub enum CoverageKind {
     /// Marks a span that might otherwise not be represented in MIR, so that
     /// coverage instrumentation can associate it with its enclosing block/BCB.
@@ -151,7 +151,7 @@ impl Debug for CoverageKind {
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
-#[derive(TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable)]
 pub enum Op {
     Subtract,
     Add,
@@ -168,15 +168,15 @@ impl Op {
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct Expression {
     pub lhs: CovTerm,
     pub op: Op,
     pub rhs: CovTerm,
 }
 
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub enum MappingKind {
     /// Associates a normal region of code with a counter/expression/zero.
     Code(CovTerm),
@@ -208,7 +208,7 @@ impl MappingKind {
 }
 
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct Mapping {
     pub kind: MappingKind,
     pub span: Span,
@@ -218,7 +218,7 @@ pub struct Mapping {
 /// to be used in conjunction with the individual coverage statements injected
 /// into the function's basic blocks.
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct FunctionCoverageInfo {
     pub function_source_hash: u64,
     pub body_span: Span,
@@ -238,7 +238,7 @@ pub struct FunctionCoverageInfo {
 /// ("Hi" indicates that this is "high-level" information collected at the
 /// THIR/MIR boundary, before the MIR-based coverage instrumentation pass.)
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct CoverageInfoHi {
     /// 1 more than the highest-numbered [`CoverageKind::BlockMarker`] that was
     /// injected into the MIR body. This makes it possible to allocate per-ID
@@ -252,23 +252,23 @@ pub struct CoverageInfoHi {
 }
 
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct BranchSpan {
     pub span: Span,
     pub true_marker: BlockMarkerId,
     pub false_marker: BlockMarkerId,
 }
 
 #[derive(Copy, Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct ConditionInfo {
     pub condition_id: ConditionId,
     pub true_next_id: Option<ConditionId>,
     pub false_next_id: Option<ConditionId>,
 }
 
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct MCDCBranchSpan {
     pub span: Span,
     pub condition_info: ConditionInfo,
@@ -277,14 +277,14 @@ pub struct MCDCBranchSpan {
 }
 
 #[derive(Copy, Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct DecisionInfo {
     pub bitmap_idx: u32,
     pub num_conditions: u16,
 }
 
 #[derive(Clone, Debug)]
-#[derive(TyEncodable, TyDecodable, Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(TyEncodable, TyDecodable, Hash, HashStable)]
 pub struct MCDCDecisionSpan {
     pub span: Span,
     pub end_markers: Vec<BlockMarkerId>,

compiler/rustc_middle/src/mir/mod.rs

@@ -358,6 +358,8 @@ pub struct Body<'tcx> {
     ///
     /// Only present if coverage is enabled and this function is eligible.
     /// Boxed to limit space overhead in non-coverage builds.
+    #[type_foldable(identity)]
+    #[type_visitable(ignore)]
     pub coverage_info_hi: Option<Box<coverage::CoverageInfoHi>>,
 
     /// Per-function coverage information added by the `InstrumentCoverage`
@@ -366,6 +368,8 @@ pub struct Body<'tcx> {
     ///
     /// If `-Cinstrument-coverage` is not active, or if an individual function
     /// is not eligible for coverage, then this should always be `None`.
+    #[type_foldable(identity)]
+    #[type_visitable(ignore)]
     pub function_coverage_info: Option<Box<coverage::FunctionCoverageInfo>>,
 }
 

compiler/rustc_middle/src/mir/syntax.rs

@@ -417,7 +417,14 @@ pub enum StatementKind<'tcx> {
     ///
     /// Interpreters and codegen backends that don't support coverage instrumentation
     /// can usually treat this as a no-op.
-    Coverage(CoverageKind),
+    Coverage(
+        // Coverage statements are unlikely to ever contain type information in
+        // the foreseeable future, so excluding them from TypeFoldable/TypeVisitable
+        // avoids some unhelpful derive boilerplate.
+        #[type_foldable(identity)]
+        #[type_visitable(ignore)]
+        CoverageKind,
+    ),
 
     /// Denotes a call to an intrinsic that does not require an unwind path and always returns.
     /// This avoids adding a new block and a terminator for simple intrinsics.