Backport "Fix stale symbol crashes in some path depended types in macro contexts" to LTS (#19051)

Backports #18077 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: Kordyjan

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -2677,7 +2677,10 @@ object Types {
       else {
         if (isType) {
           val res =
-            if (currentSymbol.isAllOf(ClassTypeParam)) argForParam(prefix)
+            val sym =
+              if (currentSymbol.isValidInCurrentRun) currentSymbol
+              else computeSymbol
+            if (sym.isAllOf(ClassTypeParam)) argForParam(prefix)
             else prefix.lookupRefined(name)
           if (res.exists) return res
           if (Config.splitProjections)
@@ -2751,14 +2754,16 @@ object Types {
     /** A reference like this one, but with the given prefix. */
     final def withPrefix(prefix: Type)(using Context): Type = {
       def reload(): NamedType = {
-        val lastSym = lastSymbol.nn
-        val allowPrivate = !lastSym.exists || lastSym.is(Private)
+        val sym =
+          if lastSymbol.nn.isValidInCurrentRun then lastSymbol.nn 
+          else computeSymbol
+        val allowPrivate = !sym.exists || sym.is(Private)
         var d = memberDenot(prefix, name, allowPrivate)
-        if (d.isOverloaded && lastSym.exists)
+        if (d.isOverloaded && sym.exists)
           d = disambiguate(d,
-                if (lastSym.signature == Signature.NotAMethod) Signature.NotAMethod
-                else lastSym.asSeenFrom(prefix).signature,
-                lastSym.targetName)
+                if (sym.signature == Signature.NotAMethod) Signature.NotAMethod
+                else sym.asSeenFrom(prefix).signature,
+                sym.targetName)
         NamedType(prefix, name, d)
       }
       if (prefix eq this.prefix) this

tests/neg-macros/i17152/DFBits.scala

@@ -0,0 +1,82 @@
+// nopos-error
+package crash
+
+import scala.quoted.*
+
+class IRDFType
+class IRDFBoolOrBit extends IRDFType
+class IRDFDecimal extends IRDFType
+class IRDFBits extends IRDFType
+
+final class DFType[+T <: IRDFType, +A]
+type DFTypeAny = DFType[IRDFType, Any]
+
+trait Baz
+
+trait Width[T]:
+  type Out <: Int
+object Width:
+  given fromDFBoolOrBit[T <: DFBoolOrBit]: Width[T] with
+    type Out = 1
+  transparent inline given [T]: Width[T] = ${ getWidthMacro[T] }
+  def getWidthMacro[T](using Quotes, Type[T]): Expr[Width[T]] =
+    '{
+      new Width[T]:
+        type Out = 1
+    }
+end Width
+
+extension [T](t: T)(using baz: Baz) def width: 1 = ???
+
+trait Check[T1 <: Int, T2 <: Int]
+
+type DFBits[W <: Int] = DFType[IRDFBits, Tuple1[W]]
+
+private object CompanionsDFBits:
+  object Val:
+    trait Candidate[R]:
+      type OutW <: Int
+      def apply(value: R): DFValOf[DFBits[OutW]]
+    object Candidate:
+      given fromDFUInt[W <: Int, R <: DFValOf[DFDecimal]]: Candidate[R] with
+        type OutW = W
+        def apply(value: R): DFValOf[DFBits[W]] =
+          import DFVal.Ops.bits
+          value.bits
+          ???
+    end Candidate
+
+    object TC:
+      import DFVal.TC
+      given DFBitsFromCandidate[
+          LW <: Int,
+          V
+      ](using candidate: Candidate[V])(using
+          check: Check[LW, candidate.OutW]
+      ): TC[DFBits[LW], V] with
+        def conv(dfType: DFBits[LW], value: V): DFValOf[DFBits[LW]] =
+          val dfVal = candidate(value)
+          ???
+    end TC
+  end Val
+
+end CompanionsDFBits
+
+type DFBoolOrBit = DFType[IRDFBoolOrBit, Any]
+type DFDecimal = DFType[IRDFDecimal, Any]
+object DFDecimal:
+  def foo(arg1: Int, arg2: Int): Unit = ???
+
+  object Val:
+    object TC:
+      import DFVal.TC
+      given [R]: TC[DFDecimal, R] = ???
+      def apply(
+          dfType: DFDecimal,
+          dfVal: DFValOf[DFDecimal]
+      ): DFValOf[DFDecimal] =
+        foo(dfType.width, dfVal.width)
+        dfVal
+    end TC
+  end Val
+end DFDecimal

tests/neg-macros/i17152/DFVal.scala

@@ -0,0 +1,25 @@
+package crash
+
+trait TCConv[T <: DFTypeAny, V, O]:
+  type Out <: O
+  def conv(dfType: T, value: V): Out
+
+class DFVal[+T <: DFTypeAny]
+type DFValAny = DFVal[DFTypeAny]
+type DFValOf[+T <: DFTypeAny] = DFVal[T]
+
+object DFVal:
+  trait TC[T <: DFTypeAny, R] extends TCConv[T, R, DFValAny]:
+    type Out = DFValOf[T]
+    final def apply(dfType: T, value: R): Out = ???
+
+  object TC:
+    export CompanionsDFBits.Val.TC.given
+  end TC
+
+  object Ops:
+    extension [T <: DFTypeAny, A, C, I](dfVal: DFVal[T])
+      def bits(using w: Width[T]): DFValOf[DFBits[w.Out]] = ???
+    end extension
+  end Ops
+end DFVal

tests/neg-macros/i17294/DFVal.scala

@@ -0,0 +1,3 @@
+package crash
+
+def bits[T](t: T)(using w: Width[T]): w.Out = ???

tests/neg-macros/i17294/Width.scala

@@ -0,0 +1,12 @@
+// nopos-error
+package crash
+import scala.quoted.*
+
+trait Width[T]:
+  type Out
+object Width:
+  transparent inline given [T]: Width[T] = ${ getWidthMacro[T] }
+  def getWidthMacro[T](using Quotes, Type[T]): Expr[Width[T]] = '{ new Width[T] {} }
+end Width
+
+val x = bits(1)

tests/pos-macros/i17294/Bar.scala

@@ -0,0 +1,6 @@
+import scala.quoted.*
+
+class Bar[T]
+object Bar:
+  transparent inline def bar[T](a: Foo, b: a.Out): Bar[T] = ${ getBarMacro[T] }
+  def getBarMacro[T](using Quotes, Type[T]): Expr[Bar[T]] = '{ new Bar[T] }

tests/pos-macros/i17294/Foo.scala

@@ -0,0 +1,3 @@
+class Foo:
+  type Out = Int
+val a = Bar.bar(new Foo(), 0)