Better split for missing-interpolator

Author: Som Snytt

src/compiler/scala/tools/nsc/ast/parser/Scanners.scala

@@ -1567,7 +1567,7 @@ trait Scanners extends ScannersCommon {
     case COMMA => "','"
     case CASECLASS => "case class"
     case CASEOBJECT => "case object"
-    case XMLSTART => "$XMLSTART$<"
+    case XMLSTART => s"$$XMLSTART$$<"
     case _ =>
       (token2name get token) match {
         case Some(name) => "'" + name + "'"

src/compiler/scala/tools/nsc/typechecker/Typers.scala

@@ -116,7 +116,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
   private final val SYNTHETIC_PRIVATE = TRANS_FLAG
 
   private final val InterpolatorCodeRegex  = """\$\{\s*(.*?)\s*\}""".r
-  private final val InterpolatorIdentRegex = """\$[$\w]+""".r // note that \w doesn't include $
+  private final val InterpolatorIdentRegex = """\$[\w]+""".r // note that \w doesn't include $
 
   /** Check that type of given tree does not contain local or private
    *  components.
@@ -6100,8 +6100,11 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
             // short-circuit on leading ${}
             if (!exprs.head.isEmpty && exprs.exists(warnableExpr))
               warn("detected an interpolated expression") // "${...}"
-          } else
-            suspiciousIdents.find(id => isPlausible(id.substring(1))).foreach(id => warn(s"detected interpolated identifier `$id`"))
+          } else suspiciousIdents.toList match {
+            case Nil =>
+            case id :: Nil => if (isPlausible(id.substring(1))) warn(s"detected interpolated identifier `$id`")
+            case all => if (all.forall(id => isPlausible(id.substring(1)))) warn(all.mkString("detected interpolated identifiers `", "`, `", "`"))
+          }
         }
         lit match {
           case Literal(Constant(s: String)) if mightBeMissingInterpolation => maybeWarn(s)

test/files/neg/forgot-interpolator.check

@@ -1,4 +1,4 @@
-forgot-interpolator.scala:6: warning: possible missing interpolator: detected interpolated identifier `$bippy`
+forgot-interpolator.scala:6: warning: possible missing interpolator: detected interpolated identifiers `$bippy`, `$bippy`
   def f = "Put the $bippy in the $bippy!" // warn 1
           ^
 forgot-interpolator.scala:16: warning: possible missing interpolator: detected an interpolated expression
@@ -25,6 +25,48 @@ forgot-interpolator.scala:92: warning: possible missing interpolator: detected i
 forgot-interpolator.scala:126: warning: possible missing interpolator: detected an interpolated expression
   @deprecated("${myProperty}")
               ^
+forgot-interpolator.scala:144: warning: possible missing interpolator: detected interpolated identifier `$foo`
+    "An important $foo message!"                              // warn on ident in scope
+    ^
+forgot-interpolator.scala:148: warning: possible missing interpolator: detected an interpolated expression
+    "A doubly important ${foo * 2} message!"                  // warn on some expr, see below
+    ^
+forgot-interpolator.scala:151: warning: possible missing interpolator: detected interpolated identifier `$bar`
+  def i = s"Try using '${ "$bar" }' instead."                 // was: no warn on space test
+                          ^
+forgot-interpolator.scala:152: warning: possible missing interpolator: detected interpolated identifier `$bar`
+  def j = s"Try using '${ "something like $bar" }' instead."  // warn
+                          ^
+forgot-interpolator.scala:158: warning: possible missing interpolator: detected an interpolated expression
+  def v = "${baz}${bar}"                                      // warn on second expr
+          ^
+forgot-interpolator.scala:159: warning: possible missing interpolator: detected an interpolated expression
+  def w = "${ op_* }"                                         // warn, only cheap ident parsing
+          ^
+forgot-interpolator.scala:160: warning: possible missing interpolator: detected an interpolated expression
+  def x = "${ bar }"                                          // warn, a cheap ident in scope
+          ^
+forgot-interpolator.scala:162: warning: possible missing interpolator: detected an interpolated expression
+  def z = "${ baz * 3}"                                       // warn, no expr parsing
+          ^
+forgot-interpolator.scala:164: warning: possible missing interpolator: detected interpolated identifier `$this`
+  def thisly = "$this"
+               ^
+forgot-interpolator.scala:165: warning: possible missing interpolator: detected an interpolated expression
+  def exprly = "${this}"
+               ^
+forgot-interpolator.scala:170: warning: possible missing interpolator: detected interpolated identifier `$s`
+  val t = "$s"
+          ^
+forgot-interpolator.scala:171: warning: possible missing interpolator: detected an interpolated expression
+  val u = "a${s}b"
+          ^
+forgot-interpolator.scala:172: warning: possible missing interpolator: detected interpolated identifier `$s`
+  val v = "a$s b"
+          ^
+forgot-interpolator.scala:177: warning: possible missing interpolator: detected interpolated identifiers `$foo`, `$bar`
+  def s = "$foo$bar"
+          ^
 error: No warnings can be incurred under -Werror.
-9 warnings
+23 warnings
 1 error

test/files/neg/forgot-interpolator.scala

@@ -126,3 +126,53 @@ object t10456 {
   @deprecated("${myProperty}")
   var myProperty: String = _
 }
+
+package pancake { }
+
+object Tester {
+  type NonVal = Int
+
+  def ok = "Don't warn on $nosymbol interpolated."
+
+  def pass = "Don't warn on $pancake package names."
+
+  def types = "Or $NonVal type symbols either."
+
+  def bar = "bar"
+  def f = {
+    val foo = "bar"
+    "An important $foo message!"                              // warn on ident in scope
+  }
+  def g = {
+    val foo = "bar"
+    "A doubly important ${foo * 2} message!"                  // warn on some expr, see below
+  }
+  def h = s"Try using '$$bar' instead."                       // no warn
+  def i = s"Try using '${ "$bar" }' instead."                 // was: no warn on space test
+  def j = s"Try using '${ "something like $bar" }' instead."  // warn
+  def k = f"Try using '$bar' instead."                        // no warn on other std interps
+  def p = "Template ${} {}"                                   // no warn on unlikely or empty expressions
+  def q = "${}$bar"                                           // disables subsequent checks! (a feature)
+  def r = "${}${bar}"                                         // disables subsequent checks! (a feature)
+
+  def v = "${baz}${bar}"                                      // warn on second expr
+  def w = "${ op_* }"                                         // warn, only cheap ident parsing
+  def x = "${ bar }"                                          // warn, a cheap ident in scope
+  def y = "${ baz }"                                          // no warn, cheap ident not in scope
+  def z = "${ baz * 3}"                                       // warn, no expr parsing
+
+  def thisly = "$this"
+  def exprly = "${this}"
+}
+
+trait X {
+  val s = "hello"
+  val t = "$s"
+  val u = "a${s}b"
+  val v = "a$s b"
+}
+
+trait DollarDollar {
+  val foo, bar = 42
+  def s = "$foo$bar"
+}