Polishings

Make tests in TypeComparer fit better with the rest

Author: odersky

Diff for: compiler/src/dotty/tools/dotc/cc/CaptureSet.scala

@@ -18,7 +18,6 @@ import TypeComparer.subsumesExistentially
 import util.common.alwaysTrue
 import scala.collection.{mutable, immutable}
 import CCState.*
-import dotty.tools.dotc.core.TypeOps.AvoidMap
 
 /** A class for capture sets. Capture sets can be constants or variables.
  *  Capture sets support inclusion constraints <:< where <:< is subcapturing.

Diff for: compiler/src/dotty/tools/dotc/core/TypeComparer.scala

@@ -298,19 +298,6 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
       }
     }
 
-    /** In capture checking, implements the logic to compare type variables which represent
-     *  capture variables.
-     *
-     *  Note: should only be called in a context where tp1 or tp2 is a type variable representing a capture variable.
-     *
-     *  @return -1 if tp1 or tp2 is not a capture variables, 1 if both tp1 and tp2 are capture variables and tp1 is a subcapture of tp2,
-     *           0 if both tp1 and tp2 are capture variables but tp1 is not a subcapture of tp2.
-     */
-    inline def tryHandleCaptureVars: Int =
-      if !(isCaptureCheckingOrSetup && tp1.derivesFrom(defn.Caps_CapSet) && tp1.derivesFrom(defn.Caps_CapSet)) then -1
-      else if (subCaptures(tp1.captureSet, tp2.captureSet, frozenConstraint).isOK) then 1
-      else 0
-
     def firstTry: Boolean = tp2 match {
       case tp2: NamedType =>
         def compareNamed(tp1: Type, tp2: NamedType): Boolean =
@@ -359,9 +346,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
                 && isSubPrefix(tp1.prefix, tp2.prefix)
                 && tp1.signature == tp2.signature
                 && !(sym1.isClass && sym2.isClass)  // class types don't subtype each other
-                || {val cv = tryHandleCaptureVars
-                    if (cv < 0) then thirdTryNamed(tp2)
-                    else cv != 0 }
+                || thirdTryNamed(tp2)
             case _ =>
               secondTry
         end compareNamed
@@ -449,14 +434,15 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
 
     def secondTry: Boolean = tp1 match {
       case tp1: NamedType =>
-        val cv = tryHandleCaptureVars
-        if (cv >= 0) then return cv != 0
         tp1.info match {
           case info1: TypeAlias =>
             if (recur(info1.alias, tp2)) return true
             if (tp1.prefix.isStable) return tryLiftedToThis1
           case _ =>
-            if (tp1 eq NothingType) || isBottom(tp1) then return true
+            if isCaptureVarComparison then
+              return subCaptures(tp1.captureSet, tp2.captureSet, frozenConstraint).isOK
+            if (tp1 eq NothingType) || isBottom(tp1) then
+              return true
         }
         thirdTry
       case tp1: TypeParamRef =>
@@ -604,6 +590,9 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
             || narrowGADTBounds(tp2, tp1, approx, isUpper = false))
           && (isBottom(tp1) || GADTusage(tp2.symbol))
 
+        if isCaptureVarComparison then
+          return subCaptures(tp1.captureSet, tp2.captureSet, frozenConstraint).isOK
+
         isSubApproxHi(tp1, info2.lo) && (trustBounds || isSubApproxHi(tp1, info2.hi))
         || compareGADT
         || tryLiftedToThis2
@@ -878,9 +867,6 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
         def compareCapturing: Boolean =
           val refs1 = tp1.captureSet
           try
-            if tp1.isInstanceOf[TypeRef] then
-              val cv = tryHandleCaptureVars
-              if (cv >= 0) then return (cv != 0)
             if refs1.isAlwaysEmpty then recur(tp1, parent2)
             else
               // The singletonOK branch is because we sometimes have a larger capture set in a singleton
@@ -1600,6 +1586,11 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
       (tp2a ne tp2) && recur(tp1, tp2a) && { opaquesUsed = true; true }
     }
 
+    def isCaptureVarComparison: Boolean =
+      isCaptureCheckingOrSetup
+      && tp1.derivesFrom(defn.Caps_CapSet)
+      && tp2.derivesFrom(defn.Caps_CapSet)
+
     // begin recur
     if tp2 eq NoType then false
     else if tp1 eq tp2 then true