Warn about unindented args

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

@@ -655,8 +655,14 @@ 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

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

@@ -1059,7 +1059,7 @@ 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)
 

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

@@ -1,4 +1,8 @@
 
+//> using options -Werror
+
+import annotation.*
+
 def f: Unit =
   identity(
     identity:
@@ -34,6 +38,7 @@ def orElse(x: Int): Unit =
     else
       false, "fail")
 
+@nowarn("msg=Unit")
 def onlyIf(x: Int): Unit =
   callme(
     if (x > 0)
@@ -57,8 +62,8 @@ def k(xs: List[Int], y: Int, z: Int) =
             x
           + y
             + z,
-          y,
-          z,
+            y,
+            z,
           )
     )
 

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
+    )