Restrict outdent in parens for certain region prefixes

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -636,8 +636,14 @@ object Scanners {
                 if skipping then
                   if r.enclosing.isClosedByUndentAt(nextWidth) then
                     insert(OUTDENT, offset)
-                else if r.isInstanceOf[InBraces] && !closingRegionTokens.contains(token) then
-                  report.warning("Line is indented too far to the left, or a `}` is missing", sourcePos())
+                else
+                  val checkable = r match
+                    case _: InBraces => true
+                    case InParens(LPAREN, _) => true
+                    case _ => false
+                  if checkable && !closingRegionTokens.contains(token) then
+                    report.warning(s"Line is indented too far to the left, or a ${showToken(r.closedBy)} is missing",
+                      sourcePos())
         else if lastWidth < nextWidth
              || lastWidth == nextWidth && (lastToken == MATCH || lastToken == CATCH) && token == CASE then
           if canStartIndentTokens.contains(lastToken) then
@@ -747,7 +753,14 @@ object Scanners {
             case _ => false
           currentRegion match
             case r: Indented if isEnclosedInParens(r.outer) =>
-              insert(OUTDENT, offset)
+              // For region prefix COLONeol, only OUTDENT if COMMA at EOL
+              if r.prefix == COLONeol then
+                val lookahead = LookaheadScanner()
+                lookahead.nextToken()
+                if lookahead.isAfterLineEnd then
+                  insert(OUTDENT, offset)
+              else
+                insert(OUTDENT, offset)
             case _ =>
               peekAhead()
               if isAfterLineEnd

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -1026,7 +1026,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
             addParamssText(
               addParamssText(keywordStr("extension "), leadingParamss)
               ~~ (defKeyword ~~ valDefText(nameIdText(tree))).close,
-             trailingParamss)
+              trailingParamss)
           else
             addParamssText(defKeyword ~~ valDefText(nameIdText(tree)), tree.paramss)
 

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

@@ -86,7 +86,7 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
 
   @Test def `filter-by-type-old` =
     check(
-      """|package example
+     """|package example
         |
         |object enrichments:
         |  implicit class A(num: Int):
@@ -99,7 +99,6 @@ class CompletionExtensionSuite extends BaseCompletionSuite:
      """|identity: String (implicit)
         |""".stripMargin, // identity2 won't be available
       filter = _.contains("(implicit)")
-
     )
 
   @Test def `filter-by-type-subtype` =

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

@@ -57,7 +57,7 @@ class CompletionKeywordSuite extends BaseCompletionSuite:
         |  **/
         |}
         |""".stripMargin,
-     "",
+      "",
       includeCommitCharacter = true
     )
 

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

@@ -1316,7 +1316,7 @@ class CompletionSuite extends BaseCompletionSuite:
           | val t: TT@@
           |}
           |""".stripMargin,
-    "TTT[A <: Int] = List[A]"
+      "TTT[A <: Int] = List[A]"
     )
 
   @Test def `type-lambda` =

presentation-compiler/test/dotty/tools/pc/tests/hover/HoverDocSuite.scala

@@ -19,20 +19,20 @@ class HoverDocSuite extends BaseHoverSuite:
 
   @Test def `doc` =
     check(
-      """object a {
-        |  <<java.util.Collections.empty@@List[Int]>>
-        |}
-        |""".stripMargin,
-     """|**Expression type**:
-        |```scala
-        |java.util.List[Int]
-        |```
-        |**Symbol signature**:
-        |```scala
-        |final def emptyList[T](): java.util.List[T]
-        |```
-        |Found documentation for java/util/Collections#emptyList().
-        |""".stripMargin,
+      """|object a {
+         |  <<java.util.Collections.empty@@List[Int]>>
+         |}
+         |""".stripMargin,
+      """|**Expression type**:
+         |```scala
+         |java.util.List[Int]
+         |```
+         |**Symbol signature**:
+         |```scala
+         |final def emptyList[T](): java.util.List[T]
+         |```
+         |Found documentation for java/util/Collections#emptyList().
+         |""".stripMargin,
     )
 
   @Test def `doc-parent` =
@@ -47,7 +47,6 @@ class HoverDocSuite extends BaseHoverSuite:
          |```
          |Found documentation for scala/collection/LinearSeqOps#headOption().
          |""".stripMargin,
-
     )
 
   @Test def `java-method` =
@@ -61,7 +60,7 @@ class HoverDocSuite extends BaseHoverSuite:
          |```
          |Found documentation for java/lang/String#substring().
          |""".stripMargin
-  )
+    )
 
   @Test def `object` =
     check(

scaladoc/test/dotty/tools/scaladoc/site/TemplateFileTests.scala

@@ -208,26 +208,26 @@ class TemplateFileTests:
     testTemplate(
       """# Hello {{ msg }}!""",
       ext = "md"
-    ) { t =>
+    ): t =>
       assertEquals(
         """<section id="hello-there">
-        |<h1 class="h500"><a href="#hello-there" class="anchor"></a>Hello there!</h1>
-        |</section>""".stripMargin,
-      t.resolveInner(RenderingContext(Map("msg" -> "there"))).code.trim())
-    }
+          |<h1 class="h500"><a href="#hello-there" class="anchor"></a>Hello there!</h1>
+          |</section>""".stripMargin,
+        t.resolveInner(RenderingContext(Map("msg" -> "there"))).code.trim()
+      )
 
   @Test
   def mixedTemplates() : Unit =
     testTemplate(
       """# Hello {{ msg }}!""",
       ext = "md"
-    ) { t =>
+    ): t =>
       assertEquals(
         """<section id="hello-there2">
-        |<h1 class="h500"><a href="#hello-there2" class="anchor"></a>Hello there2!</h1>
-        |</section>""".stripMargin,
-      t.resolveInner(RenderingContext(Map("msg" -> "there2"))).code.trim())
-    }
+          |<h1 class="h500"><a href="#hello-there2" class="anchor"></a>Hello there2!</h1>
+          |</section>""".stripMargin,
+        t.resolveInner(RenderingContext(Map("msg" -> "there2"))).code.trim()
+      )
 
   @Test
   def htmlOnly(): Unit =

tests/neg/i22527.scala

@@ -0,0 +1,25 @@
+
+//rule of thumb is COLONeol was at EOL, so COMMA must be at EOL
+def test: Unit =
+  assert(
+    identity:
+      true, "ok" // error end of statement expected but ',' found
+  )
+
+def callme[A](x: => A, msg: String) = try x.toString catch case t: RuntimeException => msg
+
+// not all indented regions require COMMA at EOL for OUTDENT
+def orElse(x: Int): Unit =
+  callme(
+    if x > 0 then
+      class X extends AnyRef, Serializable // error Not found: Serializable - did you mean Specializable?
+      true // error ',' or ')' expected, but 'true' found
+    else
+      false, "fail")
+
+def g: Unit =
+  identity(
+    x =
+      class X extends AnyRef, Serializable // error
+      27 // error
+  )

tests/neg/syntax-error-recovery.check

@@ -96,7 +96,5 @@
    | longer explanation available when compiling with `-explain`
 -- Warning: tests/neg/syntax-error-recovery.scala:61:2 -----------------------------------------------------------------
 61 |  println(bam)
-   |  ^^^^^^^
-   |  Alphanumeric method println is not declared infix; it should not be used as infix operator.
-   |  Instead, use method syntax .println(...) or backticked identifier `println`.
-   |  The latter can be rewritten automatically under -rewrite -source 3.4-migration.
+   |  ^
+   |  Line is indented too far to the left, or a ')' is missing

tests/pos/i22527.scala

@@ -0,0 +1,77 @@
+
+//> using options -Werror
+
+import annotation.*
+
+def f: Unit =
+  identity(
+    identity:
+      class X extends AnyRef, Serializable
+      42
+  )
+
+def test: Unit =
+  assert(
+    identity:
+      true,
+    "ok"
+  )
+
+def toss: Unit =
+  assert(
+    throw
+      null,
+    "ok"
+  )
+def raise: Unit =
+  assert(
+    throw
+      null, "ok" // ok now
+  )
+
+def callme[A](x: => A, msg: String) = try x.toString catch case t: RuntimeException => msg
+
+def orElse(x: Int): Unit =
+  callme(
+    if x > 0 then
+      true
+    else
+      false, "fail")
+
+@nowarn("msg=Unit")
+def onlyIf(x: Int): Unit =
+  callme(
+    if (x > 0)
+      true, "fail") // warn value discard
+
+def h(xs: List[Int]) =
+  xs.foldLeft(0)
+    (
+      (acc, x) =>
+          acc
+        + x,
+    )
+
+def sum(x: Int, y: Int, z: Int) = x+y+z
+
+def k(xs: List[Int], y: Int, z: Int) =
+  xs.foldLeft(0)
+    (
+      (acc, x) =>
+          sum(
+            x
+          + y
+            + z,
+            y,
+            z,
+          )
+    )
+
+object `arrow eol`:
+  def f(g: Int => Int, i: Int): Int = g(i)
+  def g(map: Int => Int): Int => Int = map
+  def test =
+    f(
+      g: x =>
+        x + 1, 42
+    )

tests/warn/i22527.check

@@ -0,0 +1,22 @@
+-- Warning: tests/warn/i22527.scala:60:10 ------------------------------------------------------------------------------
+60 |          y, // warn
+   |          ^
+   |          Line is indented too far to the left, or a ')' is missing
+-- Warning: tests/warn/i22527.scala:61:10 ------------------------------------------------------------------------------
+61 |          z, // warn
+   |          ^
+   |          Line is indented too far to the left, or a ')' is missing
+-- Warning: tests/warn/i22527.scala:72:2 -------------------------------------------------------------------------------
+72 |  42 // warn
+   |  ^
+   |  Line is indented too far to the left, or a ')' is missing
+-- Warning: tests/warn/i22527.scala:79:0 -------------------------------------------------------------------------------
+79 |k: // warn
+   |^
+   |Line is indented too far to the left, or a ')' is missing
+-- [E190] Potential Issue Warning: tests/warn/i22527.scala:40:6 --------------------------------------------------------
+40 |      true, "fail") // warn value discard
+   |      ^^^^
+   |      Discarded non-Unit value of type Boolean. Add `: Unit` to discard silently.
+   |
+   | longer explanation available when compiling with `-explain`

tests/warn/i22527.scala

@@ -0,0 +1,81 @@
+
+def f: Unit =
+  identity(
+    identity:
+      class X extends AnyRef, Serializable
+      42
+  )
+
+def test: Unit =
+  assert(
+    identity:
+      true,
+    "ok"
+  )
+
+def toss: Unit =
+  assert(
+    throw
+      null,
+    "ok"
+  )
+def raise: Unit =
+  assert(
+    throw
+      null, "ok" // ok now
+  )
+
+def callme[A](x: => A, msg: String) = try x.toString catch case t: RuntimeException => msg
+
+def orElse(x: Int): Unit =
+  callme(
+    if x > 0 then
+      true
+    else
+      false, "fail")
+
+def onlyIf(x: Int): Unit =
+  callme(
+    if (x > 0)
+      true, "fail") // warn value discard
+
+def h(xs: List[Int]) =
+  xs.foldLeft(0)
+    (
+      (acc, x) =>
+          acc
+        + x,
+    )
+
+def sum(x: Int, y: Int, z: Int) = x+y+z
+
+def k(xs: List[Int], y: Int, z: Int) =
+  xs.foldLeft(0)
+    (
+      (acc, x) =>
+          sum(
+            x
+          + y
+            + z,
+          y, // warn
+          z, // warn
+          )
+    )
+
+object `arrow eol`:
+  def f(g: Int => Int, i: Int): Int = g(i)
+  def g(map: Int => Int): Int => Int = map
+  def k(i: => Int) = i
+  def test =
+    f(
+      g(_ + 1),
+  42 // warn
+    )
+  def test2 =
+    f(
+      g:
+        x =>
+          x + 1,
+k: // warn
+        42
+    )