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Improve unused data usage
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@som-snytt
som-snytt committed Jul 24, 2024
1 parent b6c0fb6 commit 09d418a
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Showing 2 changed files with 87 additions and 72 deletions.
142 changes: 71 additions & 71 deletions compiler/src/dotty/tools/dotc/transform/CheckUnused.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ import dotty.tools.dotc.core.NameOps.isReplWrapperName
import dotty.tools.dotc.core.Annotations
import dotty.tools.dotc.core.Definitions
import dotty.tools.dotc.core.NameKinds.WildcardParamName
import dotty.tools.dotc.core.Symbols.Symbol
import dotty.tools.dotc.core.Symbols.{Symbol, isDeprecated}
import dotty.tools.dotc.report
import dotty.tools.dotc.reporting.{Message, UnusedSymbol as UnusedSymbolMessage}
import dotty.tools.dotc.transform.MegaPhase.MiniPhase
Expand All @@ -30,19 +30,21 @@ import dotty.tools.dotc.util.{Property, SrcPos}
import dotty.tools.dotc.util.Spans.Span
import scala.util.chaining.given

import CheckUnused.*

/** A compiler phase that checks for unused imports or definitions.
*
* Every construct that introduces a name must have at least one corresponding reference.
* The analysis is restricted to definitions of limited scope, i.e., private and local definitions.
*/
class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _key: Property.Key[CheckUnused.UnusedData]) extends MiniPhase:
import CheckUnused.*
class CheckUnused private (phaseMode: PhaseMode, suffix: String)(using Key) extends MiniPhase:

import UnusedData.*

private inline def ud(using ud: UnusedData): UnusedData = ud

private inline def go[U](inline op: UnusedData ?=> U)(using ctx: Context): ctx.type =
ctx.property(_key) match
ctx.property(summon[Key]) match
case Some(ud) => op(using ud)
case None =>
ctx
Expand All @@ -59,11 +61,12 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
// ========== SETUP ============

override def prepareForUnit(tree: tpd.Tree)(using Context): Context =
val key = summon[Key]
val data = UnusedData()
tree.getAttachment(_key).foreach(oldData =>
tree.getAttachment(key).foreach(oldData =>
data.unusedAggregate = oldData.unusedAggregate
)
ctx.fresh.setProperty(_key, data).tap(_ => tree.putAttachment(_key, data))
ctx.fresh.setProperty(key, data).tap(_ => tree.putAttachment(key, data))

// ========== END + REPORTING ==========

Expand All @@ -75,14 +78,11 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
tree

// ========== MiniPhase Prepare ==========
override def prepareForOther(tree: tpd.Tree)(using Context): Context =
// A standard tree traverser covers cases not handled by the Mega/MiniPhase
override def prepareForOther(tree: tpd.Tree)(using Context): Context = go:
traverser.traverse(tree)
ctx

override def prepareForInlined(tree: tpd.Inlined)(using Context): Context =
override def prepareForInlined(tree: tpd.Inlined)(using Context): Context = go:
traverser.traverse(tree.call)
ctx

override def prepareForIdent(tree: tpd.Ident)(using Context): Context = go:
if tree.symbol.exists then
Expand All @@ -102,13 +102,13 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
ud.registerUsed(tree.symbol, name, tree.qualifier.tpe, includeForImport = tree.qualifier.span.isSynthetic)

override def prepareForBlock(tree: tpd.Block)(using Context): Context =
pushInBlockTemplatePackageDef(tree)
pushScope(tree)

override def prepareForTemplate(tree: tpd.Template)(using Context): Context =
pushInBlockTemplatePackageDef(tree)
pushScope(tree)

override def prepareForPackageDef(tree: tpd.PackageDef)(using Context): Context =
pushInBlockTemplatePackageDef(tree)
pushScope(tree)

override def prepareForValDef(tree: tpd.ValDef)(using Context): Context = go:
traverseAnnotations(tree.symbol)
Expand Down Expand Up @@ -137,9 +137,8 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
traverseAnnotations(tree.symbol)
ud.registerPatVar(tree)

override def prepareForTypeTree(tree: tpd.TypeTree)(using Context): Context =
override def prepareForTypeTree(tree: tpd.TypeTree)(using Context): Context = go:
if !tree.isInstanceOf[tpd.InferredTypeTree] then typeTraverser.traverse(tree.tpe)
ctx

override def prepareForAssign(tree: tpd.Assign)(using Context): Context = go:
val sym = tree.lhs.symbol
Expand All @@ -149,47 +148,47 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
// ========== MiniPhase Transform ==========

override def transformBlock(tree: tpd.Block)(using Context): tpd.Tree =
popOutBlockTemplatePackageDef()
popScope(tree)
tree

override def transformTemplate(tree: tpd.Template)(using Context): tpd.Tree =
popOutBlockTemplatePackageDef()
popScope(tree)
tree

override def transformPackageDef(tree: tpd.PackageDef)(using Context): tpd.Tree =
popOutBlockTemplatePackageDef()
popScope(tree)
tree

override def transformValDef(tree: tpd.ValDef)(using Context): tpd.Tree =
go(ud.removeIgnoredUsage(tree.symbol))
go:
ud.removeIgnoredUsage(tree.symbol)
tree

override def transformDefDef(tree: tpd.DefDef)(using Context): tpd.Tree =
go(ud.removeIgnoredUsage(tree.symbol))
go:
ud.removeIgnoredUsage(tree.symbol)
tree

override def transformTypeDef(tree: tpd.TypeDef)(using Context): tpd.Tree =
go(ud.removeIgnoredUsage(tree.symbol))
go:
ud.removeIgnoredUsage(tree.symbol)
tree

private def pushScope(tree: tpd.Block | tpd.Template | tpd.PackageDef)(using Context): Context = go:
ud.pushScope(ScopeType.fromTree(tree))

// ---------- MiniPhase HELPERS -----------

private def pushInBlockTemplatePackageDef(tree: tpd.Block | tpd.Template | tpd.PackageDef)(using Context): Context = go:
ud.pushScope(UnusedData.ScopeType.fromTree(tree))

private def popOutBlockTemplatePackageDef()(using Context): Context = go:
ud.popScope()
private def popScope(tree: tpd.Block | tpd.Template | tpd.PackageDef)(using Context): Context = go:
ud.popScope(ScopeType.fromTree(tree))

/**
* This traverse is the **main** component of this phase
*
* It traverse the tree the tree and gather the data in the
* corresponding context property
*
* A standard tree traverser covers cases not handled by the Mega/MiniPhase
*/
private def traverser = new TreeTraverser:
import tpd.*
import UnusedData.ScopeType

// Register every import, definition and usage
override def traverse(tree: tpd.Tree)(using Context): Unit =
Expand All @@ -201,17 +200,17 @@ class CheckUnused private (phaseMode: CheckUnused.PhaseMode, suffix: String, _ke
case untpd.TypedSplice(tree1) => tree1
}.foreach(traverse(_)(using newCtx))
traverseChildren(tree)(using newCtx)
case ident: Ident =>
case ident: tpd.Ident =>
prepareForIdent(ident)
traverseChildren(tree)(using newCtx)
case sel: Select =>
case sel: tpd.Select =>
prepareForSelect(sel)
traverseChildren(tree)(using newCtx)
case tree: (tpd.Block | tpd.Template | tpd.PackageDef) =>
//! DIFFERS FROM MINIPHASE
pushInBlockTemplatePackageDef(tree)
pushScope(tree)
traverseChildren(tree)(using newCtx)
popOutBlockTemplatePackageDef()
popScope(tree)
case t: tpd.ValDef =>
prepareForValDef(t)
traverseChildren(tree)(using newCtx)
Expand Down Expand Up @@ -301,13 +300,14 @@ object CheckUnused:
* The key used to retrieve the "unused entity" analysis metadata,
* from the compilation `Context`
*/
private val _key = Property.StickyKey[UnusedData]
private type Key = Property.StickyKey[UnusedData]
private given Key = Property.StickyKey[UnusedData]

val OriginalName = Property.StickyKey[Name]

class PostTyper extends CheckUnused(PhaseMode.Aggregate, "PostTyper", _key)
class PostTyper extends CheckUnused(PhaseMode.Aggregate, "PostTyper")

class PostInlining extends CheckUnused(PhaseMode.Report, "PostInlining", _key)
class PostInlining extends CheckUnused(PhaseMode.Report, "PostInlining")

/** Track usages at a Context.
*
Expand All @@ -321,12 +321,13 @@ object CheckUnused:

/** The current scope during the tree traversal */
val currScopeType: Stack[ScopeType] = Stack(ScopeType.Other)
inline def peekScopeType = currScopeType.top

var unusedAggregate: Option[UnusedResult] = None

/* IMPORTS */
private val impInScope = Stack(ListBuffer.empty[ImportSelectorData])
private val usedInScope = Stack(mut.Set.empty[Usage])
private val usedInScope = Stack(mut.Map.empty[Symbol, ListBuffer[Usage]])
private val usedInPosition = mut.Map.empty[Name, mut.Set[Symbol]]
/* unused import collected during traversal */
private val unusedImport = ListBuffer.empty[ImportSelectorData]
Expand Down Expand Up @@ -382,14 +383,19 @@ object CheckUnused:
if sym.exists then
usedDef += sym
if includeForImport1 then
usedInScope.top += Usage(sym, name, prefix, isDerived)
addUsage(Usage(sym, name, prefix, isDerived))
addIfExists(sym)
addIfExists(sym.companionModule)
addIfExists(sym.companionClass)
if sym.sourcePos.exists then
for n <- name do
usedInPosition.getOrElseUpdate(n, mut.Set.empty) += sym

def addUsage(usage: Usage)(using Context): Unit =
val usages = usedInScope.top.getOrElseUpdate(usage.symbol, ListBuffer.empty)
if !usages.exists(cur => cur.name == usage.name && cur.isDerived == usage.isDerived && cur.prefix =:= usage.prefix)
then usages += usage

/** Register a symbol that should be ignored */
def addIgnoredUsage(sym: Symbol)(using Context): Unit =
doNotRegister ++= sym.everySymbol
Expand All @@ -407,7 +413,7 @@ object CheckUnused:
!tpd.languageImport(imp.expr).nonEmpty
&& !imp.isGeneratedByEnum
&& !isTransparentAndInline(imp)
&& currScopeType.top != ScopeType.ReplWrapper // #18383 Do not report top-level import's in the repl as unused
&& peekScopeType != ScopeType.ReplWrapper // #18383 Do not report top-level import's in the repl as unused
then
val qualTpe = imp.expr.tpe

Expand Down Expand Up @@ -435,7 +441,7 @@ object CheckUnused:
implicitParamInScope += memDef
else if !paramsToSkip.contains(memDef.symbol) then
explicitParamInScope += memDef
else if currScopeType.top == ScopeType.Local then
else if peekScopeType == ScopeType.Local then
localDefInScope += memDef
else if memDef.shouldReportPrivateDef then
privateDefInScope += memDef
Expand All @@ -447,10 +453,9 @@ object CheckUnused:

/** enter a new scope */
def pushScope(newScopeType: ScopeType): Unit =
// unused imports :
currScopeType.push(newScopeType)
impInScope.push(ListBuffer.empty)
usedInScope.push(mut.Set.empty)
usedInScope.push(mut.Map.empty)

def registerSetVar(sym: Symbol): Unit =
setVars += sym
Expand All @@ -460,20 +465,19 @@ object CheckUnused:
*
* - If there are imports in this scope check for unused ones
*/
def popScope()(using Context): Unit =
currScopeType.pop()
val usedInfos = usedInScope.pop()
def popScope(scopeType: ScopeType)(using Context): Unit =
assert(currScopeType.pop() == scopeType)
val selDatas = impInScope.pop()

for usedInfo <- usedInfos do
val Usage(sym, optName, prefix, isDerived) = usedInfo
selDatas.find(sym.isInImport(_, optName, prefix, isDerived)) match
for usedInfos <- usedInScope.pop().valuesIterator; usedInfo <- usedInfos do
import usedInfo.*
selDatas.find(symbol.isInImport(_, name, prefix, isDerived)) match
case Some(sel) =>
sel.markUsed()
case None =>
// Propagate the symbol one level up
if usedInScope.nonEmpty then
usedInScope.top += usedInfo
addUsage(usedInfo)
end for // each in usedInfos

for selData <- selDatas do
Expand All @@ -484,7 +488,7 @@ object CheckUnused:
/** Leave the scope and return a result set of warnings.
*/
def getUnused(using Context): UnusedResult =
popScope()
popScope(ScopeType.Other) // sentinel

def isUsedInPosition(name: Name, span: Span): Boolean =
usedInPosition.get(name) match
Expand Down Expand Up @@ -533,8 +537,6 @@ object CheckUnused:

UnusedResult(warnings.result)
end getUnused
//============================ HELPERS ====================================


/**
* Checks if import selects a def that is transparent and inline
Expand Down Expand Up @@ -634,14 +636,11 @@ object CheckUnused:
if altName.exists(explicitName => selector.rename != explicitName.toTermName) then
// if there is an explicit name, it must match
false
else
(isDerived || prefix.typeSymbol.isPackageObject || selData.qualTpe =:= prefix) && (
if isDerived then
// See i15503i.scala, grep for "package foo.test.i17156"
selData.allSymbolsDealiasedForNamed.contains(sym.dealiasAsType)
else
selData.allSymbolsForNamed.contains(sym)
)
else if isDerived then
// See i15503i.scala, grep for "package foo.test.i17156"
selData.allSymbolsDealiasedForNamed.contains(sym.dealiasAsType)
else (prefix.typeSymbol.isPackageObject || selData.qualTpe =:= prefix) &&
selData.allSymbolsForNamed.contains(sym)
else
// Wildcard
if !selData.qualTpe.member(sym.name).hasAltWith(_.symbol == sym) then
Expand All @@ -668,9 +667,10 @@ object CheckUnused:
val owner = sym.owner
trivialDefs(owner) || // is a trivial def
owner.isPrimaryConstructor ||
owner.annotations.exists ( // @depreacated
_.symbol == ctx.definitions.DeprecatedAnnot
) ||
owner.isDeprecated ||
//owner.annotations.exists ( // @depreacated
// _.symbol == ctx.definitions.DeprecatedAnnot
//) ||
owner.isAllOf(Synthetic | PrivateLocal) ||
owner.is(Accessor) ||
owner.isOverridden
Expand Down Expand Up @@ -724,7 +724,7 @@ object CheckUnused:
!sym.shouldNotReportParamOwner

private def shouldReportPrivateDef(using Context): Boolean =
currScopeType.top == ScopeType.Template && !memDef.symbol.isConstructor && memDef.symbol.is(Private, butNot = SelfName | Synthetic | CaseAccessor)
peekScopeType == ScopeType.Template && !memDef.symbol.isConstructor && memDef.symbol.is(Private, butNot = SelfName | Synthetic | CaseAccessor)

private def isUnsetVarDef(using Context): Boolean =
val sym = memDef.symbol
Expand All @@ -751,11 +751,11 @@ object CheckUnused:
object ScopeType:
/** return the scope corresponding to the enclosing scope of the given tree */
def fromTree(tree: tpd.Tree)(using Context): ScopeType = tree match
case tree: tpd.Template => if tree.symbol.name.isReplWrapperName then ReplWrapper else Template
case _:tpd.Block => Local
case _: tpd.Template => if tree.symbol.name.isReplWrapperName then ReplWrapper else Template
case _: tpd.Block => Local
case _ => Other

final case class ImportSelectorData(val qualTpe: Type, val selector: ImportSelector):
final class ImportSelectorData(val qualTpe: Type, val selector: ImportSelector):
private var myUsed: Boolean = false

def markUsed(): Unit = myUsed = true
Expand Down Expand Up @@ -787,7 +787,7 @@ object CheckUnused:
/** A symbol usage includes the name under which it was observed,
* the prefix from which it was selected, and whether it is in a derived element.
*/
case class Usage(symbol: Symbol, name: Option[Name], prefix: Type, isDerived: Boolean)
class Usage(val symbol: Symbol, val name: Option[Name], val prefix: Type, val isDerived: Boolean)
end UnusedData
extension (sym: Symbol)
/** is accessible without import in current context */
Expand All @@ -808,5 +808,5 @@ object CheckUnused:
case tp: NamedType => tp.prefix
case tp: ClassInfo => tp.prefix
case tp: TypeProxy => tp.superType.normalizedPrefix
case _ => tp
case _ => NoType
end CheckUnused
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