Add Symbol.isPatternBound

Author: liufengyun

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

@@ -540,6 +540,11 @@ object Symbols {
       d != null && d.flagsUNSAFE.is(Private)
     }
 
+    /** Is the symbol a pattern bound symbol?
+     */
+    final def isPatternBound(implicit ctx: Context): Boolean =
+      !isClass && this.is(Case, butNot = Enum | Module)
+
     /** The symbol's signature if it is completed or a method, NotAMethod otherwise. */
     final def signature(implicit ctx: Context): Signature =
       if (lastDenot != null && (lastDenot.isCompleted || lastDenot.is(Method)))

compiler/src/dotty/tools/dotc/transform/TreeChecker.scala

@@ -174,17 +174,13 @@ class TreeChecker extends Phase with SymTransformer {
 
     /** The following invariant holds:
      *
-     *  patBoundSyms.contains(sym) <=> patternBound(sym)
+     *  patBoundSyms.contains(sym) <=> sym.isPatternBound
      */
-    def patternBound(sym: Symbol)(implicit ctx: Context): Boolean =
-      (sym.isType && !sym.isClass && sym.isOneOf(Case)) ||
-        (sym.isTerm && sym.isOneOf(Case, butNot = Enum | Module))
-
     def withPatSyms[T](syms: List[Symbol])(op: => T)(implicit ctx: Context): T = {
       syms.foreach { sym =>
         assert(
-          patternBound(sym),
-          "patBoundSyms.contains(sym) => patternBound(sym) is broken." +
+          sym.isPatternBound,
+          "patBoundSyms.contains(sym) => sym.isPatternBound is broken." +
           i" Pattern bound symbol $sym has incorrect flags: " + sym.flagsString + ", line " + sym.sourcePos.line
         )
       }
@@ -214,8 +210,8 @@ class TreeChecker extends Phase with SymTransformer {
 
         if (!ctx.phase.patternTranslated)
           assert(
-            !patternBound(sym) || patBoundSyms.contains(sym),
-            i"patternBound(sym) => patBoundSyms.contains(sym) is broken, sym = $sym, line " + tree.sourcePos.line
+            !sym.isPatternBound || patBoundSyms.contains(sym),
+            i"sym.isPatternBound => patBoundSyms.contains(sym) is broken, sym = $sym, line " + tree.sourcePos.line
           )
       }