From 2c75be6a2d86ac0e86436d9e083064c9302ddced Mon Sep 17 00:00:00 2001
From: Jakub Ciesluk <323892@uwr.edu.pl>
Date: Tue, 26 Sep 2023 09:48:58 +0200
Subject: [PATCH] bugfix: Signature help in Scala 2

---
 .../internal/pc/SignatureHelpProvider.scala   |  10 +-
 .../scala/tests/pc/SignatureHelpSuite.scala   | 140 ++++++++++++++++++
 2 files changed, 149 insertions(+), 1 deletion(-)

diff --git a/mtags/src/main/scala-2/scala/meta/internal/pc/SignatureHelpProvider.scala b/mtags/src/main/scala-2/scala/meta/internal/pc/SignatureHelpProvider.scala
index 87579794dc2..d87771e22a6 100644
--- a/mtags/src/main/scala-2/scala/meta/internal/pc/SignatureHelpProvider.scala
+++ b/mtags/src/main/scala-2/scala/meta/internal/pc/SignatureHelpProvider.scala
@@ -148,7 +148,7 @@ class SignatureHelpProvider(val compiler: MetalsGlobal) {
           o.info.member(compiler.nme.apply).alternatives
         case o: ClassSymbol =>
           o.info.member(compiler.termNames.CONSTRUCTOR).alternatives
-        case m: MethodSymbol =>
+        case m: MethodSymbol if !m.isLocalToBlock =>
           m.owner.info.member(symbol.name).alternatives
         case _ =>
           symbol.alternatives
@@ -359,6 +359,14 @@ class SignatureHelpProvider(val compiler: MetalsGlobal) {
         tree match {
           case UnApply(qual, _) =>
             qual.symbol
+          // Special case: a method call with named arguments like `foo(a = 1, b = 2)` gets desugared into the following:
+          // {
+          //   val x$1 = 1
+          //   val x$2 = 2
+          //   foo(x$1, x$2)
+          // }
+          case Apply(Block(_, expr), _) =>
+            expr.symbol
           case _ =>
             NoSymbol
         }
diff --git a/tests/cross/src/test/scala/tests/pc/SignatureHelpSuite.scala b/tests/cross/src/test/scala/tests/pc/SignatureHelpSuite.scala
index 9df9f452782..c060fef7840 100644
--- a/tests/cross/src/test/scala/tests/pc/SignatureHelpSuite.scala
+++ b/tests/cross/src/test/scala/tests/pc/SignatureHelpSuite.scala
@@ -925,4 +925,144 @@ class SignatureHelpSuite extends BaseSignatureHelpSuite {
        |""".stripMargin,
   )
 
+  check(
+    "default-args".tag(
+      IgnoreScalaVersion.for3LessThan(
+        "3.4.0-RC1-bin-20231001-09ea77e-NIGHTLY"
+      )
+    ),
+    """
+      |object Main {
+      |  def foo() = {
+      |    def deployment(
+      |      fst: String,
+      |      snd: Int = 1,
+      |    ): Option[Int] = ???
+      |    val abc = deployment(@@)
+      |  }
+      |}
+      |""".stripMargin,
+    """|deployment(fst: String, snd: Int = ...): Option[Int]
+       |           ^^^^^^^^^^^
+       |""".stripMargin,
+    compat = Map(
+      "3" ->
+        """|deployment(fst: String, snd: Int): Option[Int]
+           |           ^^^^^^^^^^^
+           |""".stripMargin
+    ),
+  )
+
+  check(
+    "default-args2",
+    """
+      |object Main {
+      |  def deployment(
+      |    fst: String,
+      |    snd: Int = 1,
+      |  ): Option[Int] = ???
+      |  val abc = deployment(@@)
+      |}
+      |""".stripMargin,
+    """|deployment(fst: String, snd: Int = 1): Option[Int]
+       |           ^^^^^^^^^^^
+       |""".stripMargin,
+    compat = Map(
+      "3" ->
+        """|deployment(fst: String, snd: Int): Option[Int]
+           |           ^^^^^^^^^^^
+           |""".stripMargin
+    ),
+  )
+
+  check(
+    "default-args3",
+    """
+      |object Main {
+      |  def deployment(str: String)(
+      |    fst: String,
+      |    snd: Int = 1,
+      |  ): Option[Int] = ???
+      |  val abc = deployment("str")(
+      |    @@
+      |  )
+      |}
+      |""".stripMargin,
+    """|deployment(fst: String, snd: Int = ...): Option[Int]
+       |           ^^^^^^^^^^^
+       |""".stripMargin,
+    compat = Map(
+      "3" ->
+        """|deployment(str: String)(fst: String, snd: Int): Option[Int]
+           |                        ^^^^^^^^^^^
+           |""".stripMargin
+    ),
+  )
+
+  check(
+    "default-args4",
+    """
+      |object Main {
+      |  def deployment(str: String)(opt: Option[Int])(
+      |    fst: String,
+      |    snd: Int = 1,
+      |  ): Option[Int] = ???
+      |  val abc = deployment("str")(None)(
+      |    @@
+      |  )
+      |}
+      |""".stripMargin,
+    """|deployment(fst: String, snd: Int = ...): Option[Int]
+       |           ^^^^^^^^^^^
+       |""".stripMargin,
+    compat = Map(
+      "3" ->
+        """|deployment(str: String)(opt: Option[Int])(fst: String, snd: Int): Option[Int]
+           |                                          ^^^^^^^^^^^
+           |""".stripMargin
+    ),
+  )
+
+  check(
+    "default-args5",
+    """
+      |object Main {
+      |  def deployment(str: String)(opt: Option[Int] = None)(
+      |    fst: String,
+      |    snd: Int = 1,
+      |  ): Option[Int] = ???
+      |  val abc = deployment("str")(
+      |    @@
+      |  )
+      |}
+      |""".stripMargin,
+    """|deployment(str: String)(opt: Option[Int] = None)(fst: String, snd: Int = 1): Option[Int]
+       |                        ^^^^^^^^^^^^^^^^^^^^^^^
+       |""".stripMargin,
+    compat = Map(
+      "3" ->
+        """|deployment(str: String)(opt: Option[Int])(fst: String, snd: Int): Option[Int]
+           |                        ^^^^^^^^^^^^^^^^
+           |""".stripMargin
+    ),
+  )
+
+  check(
+    "default-args6".tag(IgnoreScala2),
+    """
+      |object Main {
+      |  def deployment(using str: String)(
+      |    fst: String,
+      |    snd: Int = 1,
+      |  ): Option[Int] = ???
+      |  val abc = deployment(using "str")(
+      |    @@
+      |  )
+      |}
+      |""".stripMargin,
+    """|deployment(using str: String)(fst: String, snd: Int): Option[Int]
+       |                              ^^^^^^^^^^^
+       |""".stripMargin,
+  )
+
 }