Retrieve a symbol for typeref to refinements in RefinedType

#14608 (comment)

Author: tanishiking

compiler/src/dotty/tools/dotc/semanticdb/TypeOps.scala

@@ -34,7 +34,7 @@ class TypeOps:
     )(using Context): Option[Symbol] =
       symtab.get((binder, name))
 
-  extension [T <: LambdaType](symtab: mutable.Map[(T, Name), Symbol])
+  extension [T <: LambdaType | RefinedType](symtab: mutable.Map[(T, Name), Symbol])
     private def lookupOrErr(
       binder: T,
       name: Name,
@@ -228,26 +228,45 @@ class TypeOps:
           val stpe = loop(tpe)
           s.ByNameType(stpe)
 
-        case TypeRef(pre, sym: Symbol) =>
-          val spre = if tpe.hasTrivialPrefix then s.Type.Empty else loop(pre)
-          val ssym = sym.symbolName
-          s.TypeRef(spre, ssym, Seq.empty)
-
+        // sym of `TypeRef(_, sym)` may not be a Symbol but Name in some cases
+        // e.g. in MatchType,
+        // case x *: xs => x *: Concat[xs, Ys]
+        // x and xs should have a typebounds <: Any, >: Nothing
+        // but Any (and Nothing) are represented as TypeRef(<scala>, "Any" <- Name)
         case tr @ TypeRef(pre, _) if tr.symbol != NoSymbol =>
           val spre = if tpe.hasTrivialPrefix then s.Type.Empty else loop(pre)
           val ssym = tr.symbol.symbolName
           s.TypeRef(spre, ssym, Seq.empty)
 
-        case TermRef(pre, sym: Symbol) =>
+        // when TypeRef refers the refinement of RefinedType e.g.
+        // TypeRef for `foo.B` in `trait T[A] { val foo: { type B = A } = ???; def bar(b: foo.B) = () }` has NoSymbol
+        case TypeRef(pre, name: Name) =>
           val spre = if tpe.hasTrivialPrefix then s.Type.Empty else loop(pre)
-          val ssym = sym.symbolName
-          s.SingleType(spre, ssym)
+          val maybeSym = pre.widen.dealias match
+            case rt: RefinedType =>
+              refinementSymtab.lookupOrErr(rt, name, rt.typeSymbol)
+            case _ => None
+          maybeSym match
+            case Some(sym) =>
+              s.TypeRef(spre, sym.symbolName, Seq.empty)
+            case None => s.Type.Empty
 
         case tr @ TermRef(pre, _) if tr.symbol != NoSymbol =>
           val spre = if(tpe.hasTrivialPrefix) s.Type.Empty else loop(pre)
           val ssym = tr.symbol.symbolName
           s.SingleType(spre, ssym)
 
+        case TermRef(pre, name: Name) =>
+          val spre = if tpe.hasTrivialPrefix then s.Type.Empty else loop(pre)
+          val maybeSym = pre.widen.dealias match
+            case rt: RefinedType =>
+              refinementSymtab.lookupOrErr(rt, name, rt.typeSymbol)
+            case _ => None
+          maybeSym match
+            case Some(sym) =>
+              s.SingleType(spre, sym.symbolName)
+            case None => s.Type.Empty
+
         case ThisType(TypeRef(_, sym: Symbol)) =>
           s.ThisType(sym.symbolName)
 
@@ -458,9 +477,6 @@ class TypeOps:
     private def hasTrivialPrefix(using Context): Boolean =
       def checkTrivialPrefix(pre: Type, sym: Symbol)(using Context): Boolean =
         pre =:= sym.owner.thisType
-      // Make sure `tr.symbol != NoSymbol` where `tr @ TypeRef(...)`, that happens
-      // when TypeRef refers the refinement of RefinedType e.g.
-      // TypeRef for `foo.B` in `trait T[A] { val foo: { type B = A } = ???; def bar(b: foo.B) = () }` has NoSymbol
       tpe match {
         case TypeRef(pre, sym: Symbol) =>
           checkTrivialPrefix(pre, sym)

tests/semanticdb/expect/dep-match.expect.scala

@@ -0,0 +1,9 @@
+object Test_depmatch/*<-_empty_::Test_depmatch.*/ {
+  type Foo/*<-_empty_::Test_depmatch.Foo#*/ = Int/*->scala::Int#*/ { type U/*<-local0*/ }
+  type Bar/*<-_empty_::Test_depmatch.Bar#*/[T/*<-_empty_::Test_depmatch.Bar#[T]*/] = T/*->_empty_::Test_depmatch.Bar#[T]*/ match {
+    case Unit/*->scala::Unit#*/ => Unit/*->scala::Unit#*/
+  }
+  inline def baz/*<-_empty_::Test_depmatch.baz().*/(foo/*<-_empty_::Test_depmatch.baz().(foo)*/: Foo/*->_empty_::Test_depmatch.Foo#*/): Unit/*->scala::Unit#*/ = {
+    val v/*<-local1*/: Bar/*->_empty_::Test_depmatch.Bar#*/[foo/*->_empty_::Test_depmatch.baz().(foo)*/.U] = ???/*->scala::Predef.`???`().*/
+  }
+}

tests/semanticdb/expect/dep-match.scala

@@ -0,0 +1,9 @@
+object Test_depmatch {
+  type Foo = Int { type U }
+  type Bar[T] = T match {
+    case Unit => Unit
+  }
+  inline def baz(foo: Foo): Unit = {
+    val v: Bar[foo.U] = ???
+  }
+}

tests/semanticdb/metac.expect

@@ -71,8 +71,8 @@ advanced/Structural# => class Structural extends Object { self: Structural => +6
 advanced/Structural#T# => trait T [typeparam A ] extends Object { self: T[A] => +4 decls }
 advanced/Structural#T#[A] => typeparam A 
 advanced/Structural#T#`<init>`(). => primary ctor <init> [typeparam A ](): T[A]
-advanced/Structural#T#bar(). => method bar (param b: <?>): Unit
-advanced/Structural#T#bar().(b) => param b: <?>
+advanced/Structural#T#bar(). => method bar (param b: foo.B): Unit
+advanced/Structural#T#bar().(b) => param b: foo.B
 advanced/Structural#T#foo. => val method foo Object { type B  = A }
 advanced/Structural#`<init>`(). => primary ctor <init> (): Structural
 advanced/Structural#s1(). => method s1 => Object { abstract val method x Int }
@@ -3703,6 +3703,46 @@ Occurrences:
 [4:18..4:21): Int -> scala/Int#
 [4:26..4:30): Unit -> scala/Unit#
 
+expect/dep-match.scala
+----------------------
+
+Summary:
+Schema => SemanticDB v4
+Uri => dep-match.scala
+Text => empty
+Language => Scala
+Symbols => 8 entries
+Occurrences => 17 entries
+
+Symbols:
+_empty_/Test_depmatch. => final object Test_depmatch extends Object { self: Test_depmatch.type => +4 decls }
+_empty_/Test_depmatch.Bar# => type Bar [typeparam T ] = T match { Unit => Unit }
+_empty_/Test_depmatch.Bar#[T] => typeparam T 
+_empty_/Test_depmatch.Foo# => type Foo  = Int { type U  }
+_empty_/Test_depmatch.baz(). => inline macro baz (param foo: Foo): Unit
+_empty_/Test_depmatch.baz().(foo) => param foo: Foo
+local0 => type U 
+local1 => val local v: Bar[foo.U]
+
+Occurrences:
+[0:7..0:20): Test_depmatch <- _empty_/Test_depmatch.
+[1:7..1:10): Foo <- _empty_/Test_depmatch.Foo#
+[1:13..1:16): Int -> scala/Int#
+[1:24..1:25): U <- local0
+[2:7..2:10): Bar <- _empty_/Test_depmatch.Bar#
+[2:11..2:12): T <- _empty_/Test_depmatch.Bar#[T]
+[2:16..2:17): T -> _empty_/Test_depmatch.Bar#[T]
+[3:9..3:13): Unit -> scala/Unit#
+[3:17..3:21): Unit -> scala/Unit#
+[5:13..5:16): baz <- _empty_/Test_depmatch.baz().
+[5:17..5:20): foo <- _empty_/Test_depmatch.baz().(foo)
+[5:22..5:25): Foo -> _empty_/Test_depmatch.Foo#
+[5:28..5:32): Unit -> scala/Unit#
+[6:8..6:9): v <- local1
+[6:11..6:14): Bar -> _empty_/Test_depmatch.Bar#
+[6:15..6:18): foo -> _empty_/Test_depmatch.baz().(foo)
+[6:24..6:27): ??? -> scala/Predef.`???`().
+
 expect/exports-example-Codec.scala
 ----------------------------------