Backport "Add custom matchers for completions (fuzzy search for prese…

…ntation compiler)" to LTS (#21062)

Backports #19850 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -71,10 +71,11 @@ object Completion:
     mode: Mode,
     rawPrefix: String,
     tpdPath: List[tpd.Tree],
-    untpdPath: List[untpd.Tree]
+    untpdPath: List[untpd.Tree],
+    customMatcher: Option[Name => Boolean] = None
   )(using Context): CompletionMap =
     val adjustedPath = typeCheckExtensionConstructPath(untpdPath, tpdPath, pos)
-    computeCompletions(pos, mode, rawPrefix, adjustedPath)
+    computeCompletions(pos, mode, rawPrefix, adjustedPath, customMatcher)
 
   /**
    * Inspect `path` to determine what kinds of symbols should be considered.
@@ -193,11 +194,12 @@ object Completion:
     .flatten.getOrElse(tpdPath)
 
   private def computeCompletions(
-    pos: SourcePosition, mode: Mode, rawPrefix: String, adjustedPath: List[tpd.Tree]
+    pos: SourcePosition, mode: Mode, rawPrefix: String, adjustedPath: List[tpd.Tree], matches: Option[Name => Boolean]
   )(using Context): CompletionMap =
     val hasBackTick = rawPrefix.headOption.contains('`')
     val prefix = if hasBackTick then rawPrefix.drop(1) else rawPrefix
-    val completer = new Completer(mode, prefix, pos)
+    val matches0 = matches.getOrElse(_.startsWith(prefix))
+    val completer = new Completer(mode, pos, matches0)
 
     val result = adjustedPath match
       // Ignore synthetic select from `This` because in code it was `Ident`
@@ -209,7 +211,6 @@ object Completion:
       case _                                                                    => completer.scopeCompletions
 
     interactiv.println(i"""completion info with pos    = $pos,
-                          |                     prefix = ${completer.prefix},
                           |                     term   = ${completer.mode.is(Mode.Term)},
                           |                     type   = ${completer.mode.is(Mode.Type)},
                           |                     scope  = ${completer.mode.is(Mode.Scope)},
@@ -311,13 +312,13 @@ object Completion:
 
   /** Computes code completions depending on the context in which completion is requested
    *  @param mode    Should complete names of terms, types or both
-   *  @param prefix  The prefix that all suggested completions should start with
    *  @param pos     Cursor position where completion was requested
+   *  @param matches Function taking name used to filter completions
    *
    *  For the results of all `xyzCompletions` methods term names and type names are always treated as different keys in the same map
    *  and they never conflict with each other.
    */
-  class Completer(val mode: Mode, val prefix: String, pos: SourcePosition):
+  class Completer(val mode: Mode, pos: SourcePosition, matches: Name => Boolean):
     /** Completions for terms and types that are currently in scope:
      *  the members of the current class, local definitions and the symbols that have been imported,
      *  recursively adding completions from outer scopes.
@@ -524,7 +525,7 @@ object Completion:
       // There are four possible ways for an extension method to be applicable
 
       // 1. The extension method is visible under a simple name, by being defined or inherited or imported in a scope enclosing the reference.
-      val termCompleter = new Completer(Mode.Term, prefix, pos)
+      val termCompleter = new Completer(Mode.Term, pos, matches)
       val extMethodsInScope = termCompleter.scopeCompletions.toList.flatMap:
         case (name, denots) => denots.collect:
           case d: SymDenotation if d.isTerm && d.termRef.symbol.is(Extension) => (d.termRef, name.asTermName)
@@ -556,7 +557,7 @@ object Completion:
      *   2. satisfy [[Completion.isValidCompletionSymbol]]
      */
     private def include(denot: SingleDenotation, nameInScope: Name)(using Context): Boolean =
-      nameInScope.startsWith(prefix) &&
+      matches(nameInScope) &&
       completionsFilter(NoType, nameInScope) &&
       isValidCompletionSymbol(denot.symbol, mode)
 
@@ -605,7 +606,6 @@ object Completion:
     private def implicitConversionTargets(qual: tpd.Tree)(using Context): Set[SearchSuccess] = {
       val typer = ctx.typer
       val conversions = new typer.ImplicitSearch(defn.AnyType, qual, pos.span).allImplicits
-      conversions.map(_.tree.typeOpt)
 
       interactiv.println(i"implicit conversion targets considered: ${conversions.toList}%, %")
       conversions

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -509,7 +509,8 @@ object Implicits:
          |must be more specific than $target"""
 
     override def msg(using Context) =
-      super.msg.append("\nThe expected type $target is not specific enough, so no search was attempted")
+      super.msg.append(i"\nThe expected type $target is not specific enough, so no search was attempted")
+
     override def toString = s"TooUnspecific"
 
   /** An ambiguous implicits failure */

presentation-compiler/src/main/dotty/tools/pc/completions/Completions.scala

@@ -16,6 +16,7 @@ import dotty.tools.dotc.ast.untpd
 import dotty.tools.dotc.core.Comments.Comment
 import dotty.tools.dotc.core.Constants.Constant
 import dotty.tools.dotc.core.Contexts.*
+import dotty.tools.dotc.core.Denotations.SingleDenotation
 import dotty.tools.dotc.core.Flags
 import dotty.tools.dotc.core.Flags.*
 import dotty.tools.dotc.core.NameOps.*
@@ -26,14 +27,13 @@ import dotty.tools.dotc.core.Symbols.*
 import dotty.tools.dotc.core.Types.*
 import dotty.tools.dotc.interactive.Completion
 import dotty.tools.dotc.interactive.Completion.Mode
+import dotty.tools.dotc.interactive.Interactive
 import dotty.tools.dotc.util.SourcePosition
 import dotty.tools.dotc.util.SrcPos
 import dotty.tools.pc.AutoImports.AutoImportsGenerator
-import dotty.tools.pc.completions.OverrideCompletions.OverrideExtractor
 import dotty.tools.pc.buildinfo.BuildInfo
+import dotty.tools.pc.completions.OverrideCompletions.OverrideExtractor
 import dotty.tools.pc.utils.MtagsEnrichments.*
-import dotty.tools.dotc.core.Denotations.SingleDenotation
-
 
 class Completions(
     text: String,
@@ -102,9 +102,13 @@ class Completions(
     end if
   end includeSymbol
 
+  lazy val fuzzyMatcher: Name => Boolean = name =>
+    if completionMode.is(Mode.Member) then CompletionFuzzy.matchesSubCharacters(completionPos.query, name.toString)
+    else CompletionFuzzy.matches(completionPos.query, name.toString)
+
   def enrichedCompilerCompletions(qualType: Type): (List[CompletionValue], SymbolSearch.Result) =
     val compilerCompletions = Completion
-      .rawCompletions(completionPos.originalCursorPosition, completionMode, completionPos.query, path, adjustedPath)
+      .rawCompletions(completionPos.originalCursorPosition, completionMode, completionPos.query, path, adjustedPath, Some(fuzzyMatcher))
 
     compilerCompletions
       .toList
@@ -423,7 +427,7 @@ class Completions(
 
       // class Fo@@
       case (td: TypeDef) :: _
-          if Fuzzy.matches(
+          if CompletionFuzzy.matches(
             td.symbol.name.decoded.replace(Cursor.value, "").nn,
             filename
           ) =>

presentation-compiler/test/dotty/tools/pc/base/BaseCompletionSuite.scala

@@ -123,7 +123,7 @@ abstract class BaseCompletionSuite extends BasePCSuite:
 
     if (assertSingleItem && items.length != 1) then
       fail(
-        s"expected single completion item, obtained ${items.length} items.\n${items}"
+        s"expected single completion item, obtained ${items.length} items.\n${items.map(_.getLabel.nn + "\n")}"
       )
 
     if (items.size <= itemIndex) then

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionDocSuite.scala

@@ -156,8 +156,8 @@ class CompletionDocSuite extends BaseCompletionSuite:
         |Found documentation for scala/collection/Iterator.
         |Iterator scala.collection
         |""".stripMargin,
-
-      includeDocs = true
+      includeDocs = true,
+      topLines = Some(1)
     )
 
   @Test def `scala5` =

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionExtensionSuite.scala

@@ -17,21 +17,24 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |def main = 100.inc@@
          |""".stripMargin,
       """|incr: Int (extension)
+         |asInstanceOf[X0]: X0
+         |isInstanceOf[X0]: Boolean
          |""".stripMargin
     )
 
   @Test def `simple-old-syntax` =
     check(
-      """|package example
+      """package example
         |
         |object Test:
         |  implicit class TestOps(a: Int):
         |    def testOps(b: Int): String = ???
         |
         |def main = 100.test@@
         |""".stripMargin,
-      """|testOps(b: Int): String (implicit)
-        |""".stripMargin
+      """testOps(b: Int): String (implicit)
+        |""".stripMargin,
+      topLines = Some(1)
     )
 
   @Test def `simple2` =
@@ -93,8 +96,10 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
         |
         |def main = "foo".iden@@
         |""".stripMargin,
-      """|identity: String (implicit)
-        |""".stripMargin // identity2 won't be available
+     """|identity: String (implicit)
+        |""".stripMargin, // identity2 won't be available
+      filter = _.contains("(implicit)")
+
     )
 
   @Test def `filter-by-type-subtype` =
@@ -152,7 +157,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |    def incr: Int = num + 1
          |
          |def main = 100.incr
-         |""".stripMargin
+         |""".stripMargin,
+      assertSingleItem = false
     )
 
   @Test def `simple-edit-old` =
@@ -174,7 +180,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |    def incr: Int = num + 1
          |
          |def main = 100.incr
-         |""".stripMargin
+         |""".stripMargin,
+      assertSingleItem = false
     )
 
   @Test def `simple-edit-suffix` =
@@ -262,6 +269,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |  def main = 100.inc@@
          |""".stripMargin,
       """|incr: Int (extension)
+         |asInstanceOf[X0]: X0
+         |isInstanceOf[X0]: Boolean
          |""".stripMargin
     )
 
@@ -276,6 +285,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |  def main = 100.inc@@
          |""".stripMargin,
       """|incr: Int (implicit)
+         |asInstanceOf[X0]: X0
+         |isInstanceOf[X0]: Boolean
          |""".stripMargin
     )
 
@@ -290,6 +301,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |  def main = 100.inc@@
          |""".stripMargin,
       """|incr: Int (extension)
+         |asInstanceOf[X0]: X0
+         |isInstanceOf[X0]: Boolean
          |""".stripMargin
     )
 
@@ -304,6 +317,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |  def main = 100.inc@@
          |""".stripMargin,
       """|incr: Int (implicit)
+         |asInstanceOf[X0]: X0
+         |isInstanceOf[X0]: Boolean
          |""".stripMargin
     )
 
@@ -391,7 +406,8 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |testVal: Int (implicit)
          |testVar: Int (implicit)
          |testOps(b: Int): String (implicit)
-         |""".stripMargin
+         |""".stripMargin,
+      topLines = Some(4)
     )
 
   @Test def `implicit-val-edit` =
@@ -413,5 +429,6 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
          |    val testVal: Int = 42
          |
          |def main = 100.testVal
-         |""".stripMargin
+         |""".stripMargin,
+      assertSingleItem = false
     )

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionKeywordSuite.scala

@@ -695,28 +695,26 @@ class CompletionKeywordSuite extends BaseCompletionSuite:
 
   @Test def `derives-with-extends` =
     check(
-      """
-        |package foo
-        |
-        |trait Bar {}
-        |trait Baz {}
-        |
-        |class Foo(x: Int) extends Bar with Baz der@@
-                """.stripMargin,
+      """|package foo
+         |
+         |trait Bar {}
+         |trait Baz {}
+         |
+         |class Foo(x: Int) extends Bar with Baz der@@
+         |""".stripMargin,
       """|derives
          |""".stripMargin
     )
 
   @Test def `derives-with-constructor-extends` =
     check(
-      """
-        |package foo
-        |
-        |trait Bar {}
-        |class Baz(b: Int) {}
-        |
-        |class Foo(x: Int) extends Bar with Baz(1) der@@
-                  """.stripMargin,
+      """|package foo
+         |
+         |trait Bar {}
+         |class Baz(b: Int) {}
+         |
+         |class Foo(x: Int) extends Bar with Baz(1) der@@
+         |""".stripMargin,
       """|derives
          |""".stripMargin
     )

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionOverrideSuite.scala

@@ -925,12 +925,15 @@ class CompletionOverrideSuite extends BaseCompletionSuite:
          |   def@@
          |}
          |""".stripMargin,
+
       """|def hello1: Int
          |override def equals(x$0: Any): Boolean
          |override def hashCode(): Int
+         |override def toString(): String
+         |override val hello2: Int
          |""".stripMargin,
       includeDetail = false,
-      topLines = Some(3)
+      topLines = Some(5)
     )
 
   @Test def `path-dependent` =

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionSnippetNegSuite.scala

@@ -16,12 +16,12 @@ class CompletionSnippetNegSuite extends BaseCompletionSuite:
 
   @Test def `member` =
     checkSnippet(
-      """
-        |object Main {
-        |  List.appl@@
-        |}
-        |""".stripMargin,
-      "apply"
+      """|object Main {
+         |  List.appl@@
+         |}
+         |""".stripMargin,
+      """|apply
+         |unapplySeq""".stripMargin
     )
 
   @Test def `scope` =

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionSnippetSuite.scala

@@ -15,6 +15,7 @@ class CompletionSnippetSuite extends BaseCompletionSuite:
         |}
         |""".stripMargin,
       """|apply($0)
+         |unapplySeq($0)
          |""".stripMargin
     )
 
@@ -429,7 +430,8 @@ class CompletionSnippetSuite extends BaseCompletionSuite:
           |  extension (s: String)
           |    def bar = 0
           |  val bar = "abc".bar
-      """.stripMargin
+      """.stripMargin,
+      filter = _.contains("bar: Int")
     )
 
   // https://github.com/scalameta/metals/issues/4004
@@ -446,5 +448,6 @@ class CompletionSnippetSuite extends BaseCompletionSuite:
           |  extension (s: String)
           |    def bar() = 0
           |  val bar = "abc".bar()
-      """.stripMargin
+      """.stripMargin,
+      filter = _.contains("bar: Int")
     )