improve error messages

build.sbt

@@ -94,7 +94,8 @@ val mimaFilterSettings = Seq(
     ProblemFilters.exclude[MissingClassProblem]("scala.reflect.runtime.JavaMirrors$JavaMirror$typeTagCache$"),
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.reflect.api.TypeTags.TypeTagImpl"),
     ProblemFilters.exclude[DirectMissingMethodProblem]("scala.reflect.api.Universe.TypeTagImpl"),
-    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.StringContext.processUnicode")
+    ProblemFilters.exclude[DirectMissingMethodProblem]("scala.StringContext.processUnicode"),
+    ProblemFilters.exclude[MissingClassProblem]("scala.StringContext$InvalidUnicodeEscapeException")
   ),
 )
 

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

@@ -760,21 +760,28 @@ trait Scanners extends ScannersCommon {
 
     private def unclosedStringLit(): Unit = syntaxError("unclosed string literal")
 
-    private def replaceUnicodeEscapes(warn: Boolean): Unit = 
+    private def replaceUnicodeEscapesInTriple(): Unit = 
       if(strVal != null) {
-        val replaced = StringContext.processUnicode(strVal)
-        if(warn && replaced != strVal) {
-          deprecationWarning("Unicode escapes in triple quoted strings and raw interpolations are deprecated, use the literal character instead" , since="2.13.1")
+        try {
+          val replaced = StringContext.processUnicode(strVal)
+          if(replaced != strVal) {
+            val diffPosition = replaced.zip(strVal).zipWithIndex.collectFirst{ case ((r, o), i) if r != o => i}.getOrElse(replaced.length - 1)
+            deprecationWarning(offset + 3 + diffPosition, "Unicode escapes in triple quoted strings are deprecated, use the literal character instead", since="2.13.1")
+          }
+          strVal = replaced
+        } catch {
+          case ue: StringContext.InvalidUnicodeEscapeException => {
+            syntaxError(offset + ue.index, ue.getMessage())
+          }
         }
-        strVal = replaced
       }
 
     @tailrec private def getRawStringLit(): Unit = {
       if (ch == '\"') {
         nextRawChar()
         if (isTripleQuote()) {
           setStrVal()
-          if(!currentRun.isScala214) replaceUnicodeEscapes(true)
+          if(!currentRun.isScala214) replaceUnicodeEscapesInTriple()
           token = STRINGLIT
         } else
           getRawStringLit()
@@ -901,41 +908,49 @@ trait Scanners extends ScannersCommon {
           syntaxError(start, s"octal escape literals are unsupported: use $alt instead")
           putChar(oct.toChar)
         } else {
-          ch match {
-            case 'b'  => putChar('\b')
-            case 't'  => putChar('\t')
-            case 'n'  => putChar('\n')
-            case 'f'  => putChar('\f')
-            case 'r'  => putChar('\r')
-            case '\"' => putChar('\"')
-            case '\'' => putChar('\'')
-            case '\\' => putChar('\\')
-            case 'u'  => getUEscape()
-            case _    => invalidEscape()
+          if (ch == 'u') {
+            if (getUEscape()) nextChar()
+          }
+          else {
+            ch match {
+              case 'b'  => putChar('\b')
+              case 't'  => putChar('\t')
+              case 'n'  => putChar('\n')
+              case 'f'  => putChar('\f')
+              case 'r'  => putChar('\r')
+              case '\"' => putChar('\"')
+              case '\'' => putChar('\'')
+              case '\\' => putChar('\\')
+              case _    => invalidEscape()
+            }
+            nextChar()
           }
-          nextChar()
         }
       } else  {
         putChar(ch)
         nextChar()
       }
 
-    private def getUEscape(): Unit = {
+    private def getUEscape(): Boolean = {
       while (ch == 'u') nextChar()
       var codepoint = 0
       var digitsRead = 0
-      while(digitsRead < 4){
+      while (digitsRead < 4) {
         if (digitsRead > 0) nextChar()
         val digit = digit2int(ch, 16)
         digitsRead += 1
         if (digit >= 0) {
           codepoint = codepoint << 4
           codepoint += digit
         }
-        else invalidUnicodeEscape(digitsRead)
+        else {
+          invalidUnicodeEscape(digitsRead)
+          return false
+        }
       }
       val found = codepoint.asInstanceOf[Char]
       putChar(found)
+      true
     }
 
 
@@ -945,7 +960,7 @@ trait Scanners extends ScannersCommon {
     }
 
     protected def invalidUnicodeEscape(n: Int): Unit = {
-      syntaxError(charOffset -n, "invalid unicode escape")
+      syntaxError(charOffset - n, "invalid unicode escape")
       putChar(ch)
     }
 

src/compiler/scala/tools/reflect/FastStringInterpolator.scala

@@ -36,10 +36,11 @@ trait FastStringInterpolator extends FormatInterpolator {
                              else if (isRaw) {
                                val processed = StringContext.processUnicode(stringVal)
                                if(processed != stringVal){
-                                 var diffindex = processed.zip(stringVal).zipWithIndex.collectFirst{
+                                 val diffindex = processed.zip(stringVal).zipWithIndex.collectFirst {
                                    case ((p, o), i) if p != o => i
                                  }.getOrElse(processed.length - 1)
-                                 c.warning(lit.pos, "Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14")
+
+                                 c.warning(lit.pos.withShift(diffindex), "Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14. Use the literal character instead.")
                                }
                                processed
                              }
@@ -48,7 +49,8 @@ trait FastStringInterpolator extends FormatInterpolator {
             treeCopy.Literal(lit, k).setType(ConstantType(k))
           }
         catch {
-          case e: StringContext.InvalidEscapeException => c.abort(parts.head.pos.withShift(e.index), e.getMessage)
+          case ie: StringContext.InvalidEscapeException => c.abort(parts.head.pos.withShift(ie.index), ie.getMessage)
+          case iue: StringContext.InvalidUnicodeEscapeException => c.abort(parts.head.pos.withShift(iue.index), iue.getMessage)
         }
 
       val argsIndexed = args.toVector

src/library/scala/StringContext.scala

@@ -324,11 +324,15 @@ object StringContext {
   class InvalidEscapeException(str: String, val index: Int) extends IllegalArgumentException(
     s"""invalid escape ${
       require(index >= 0 && index < str.length)
-      val ok = s"""[\\b, \\t, \\n, \\f, \\r, \\, \\", \\', \\uxxxx]"""
+      val ok = s"""[\\b, \\t, \\n, \\f, \\r, \\\\, \\", \\', \\uxxxx]"""
       if (index == str.length - 1) "at terminal" else s"'\\${str(index + 1)}' not one of $ok at"
     } index $index in "$str". Use \\\\ for literal \\."""
   )
 
+  protected[scala] class InvalidUnicodeEscapeException(str: String, val escapeStart: Int, val index: Int) extends IllegalArgumentException(
+    s"""invalid unicode escape at index $index of $str"""
+  )
+
   private[this] def readUEscape(src: String, startindex: Int): (Char, Int) = {
     val len = src.length()
     def loop(uindex: Int): (Char, Int) = {
@@ -340,14 +344,16 @@ object StringContext {
           val digitsRead = dindex
           (codepoint.asInstanceOf[Char], usRead + digitsRead)
         }
+        else if (dindex + uindex >= len)
+          throw new InvalidUnicodeEscapeException(src, startindex, dindex + uindex)
         else {
           val ch = src(dindex + uindex)
           val e = ch.asDigit
           if(e >= 0 && e <= 15) loopCP(dindex + 1, (codepoint << 4) + e)
-          else throw new InvalidEscapeException(src, startindex)
+          else throw new InvalidUnicodeEscapeException(src, startindex, dindex + uindex)
         }
       }
-      if(uindex > len) throw new InvalidEscapeException(src, startindex)
+      if(uindex >= len) throw new InvalidUnicodeEscapeException(src, startindex, uindex - 1)
       //allow one or more `u` characters between the
       //backslash and the code unit
       else if(src(uindex) == 'u') loop(uindex + 1)

test/files/neg/t3220-1.check

@@ -0,0 +1,25 @@
+t3220-1.scala:2: error: invalid unicode escape
+  val badsingle = "foo \unope that's wrong"
+                         ^
+t3220-1.scala:3: error: invalid unicode escape at index 6 of foo \unope that's wrong
+  val badtriple = """foo \unope that's wrong"""
+                        ^
+t3220-1.scala:4: error: invalid unicode escape
+  val caretPos = "foo \u12x3 pos @ x"
+                        ^
+t3220-1.scala:5: error: invalid unicode escape
+  val caretPos2 = "foo \uuuuuuu12x3 pos @ x"
+                               ^
+t3220-1.scala:6: error: invalid unicode escape
+  val carPosTerm = "foo \u123"
+                          ^
+t3220-1.scala:7: error: invalid unicode escape
+  val halfAnEscape = "foo \u12"
+                            ^
+t3220-1.scala:8: error: invalid unicode escape
+  val halfAnEscapeChar = '\u45'
+                            ^
+t3220-1.scala:9: error: invalid unicode escape
+  val `half An Identifier\u45` = "nope"
+                           ^
+8 errors found

test/files/neg/t3220-1.scala

@@ -0,0 +1,10 @@
+object Example {
+  val badsingle = "foo \unope that's wrong"
+  val badtriple = """foo \unope that's wrong""" 
+  val caretPos = "foo \u12x3 pos @ x"
+  val caretPos2 = "foo \uuuuuuu12x3 pos @ x"
+  val carPosTerm = "foo \u123"
+  val halfAnEscape = "foo \u12"
+  val halfAnEscapeChar = '\u45'
+  val `half An Identifier\u45` = "nope"
+}

test/files/neg/t3220-2.check

@@ -0,0 +1,16 @@
+t3220-2.scala:2: error: invalid unicode escape at index 6 of foo \unope that's wrong
+  val badInters1 = s"foo \unope that's wrong"
+                           ^
+t3220-2.scala:3: error: invalid unicode escape at index 8 of foo \u12
+  val badIntersEnd1 = s"foo \u12"
+                                ^
+t3220-2.scala:4: error: invalid unicode escape at index 6 of foo \unope that's wrong
+  val badInterRaw1 = raw"foo \unope that's wrong"
+                               ^
+t3220-2.scala:6: error: invalid unicode escape at index 6 of foo \unope that's wrong
+  val badInters3 = s"""foo \unope that's wrong"""
+                             ^
+t3220-2.scala:7: error: invalid unicode escape at index 6 of foo \unope that's wrong
+  val badInterRaw3 = raw"""foo \unope that's wrong"""
+                                 ^
+5 errors found

test/files/neg/t3220-2.scala

@@ -0,0 +1,8 @@
+object Example {
+  val badInters1 = s"foo \unope that's wrong"
+  val badIntersEnd1 = s"foo \u12"
+  val badInterRaw1 = raw"foo \unope that's wrong"
+  val badInterRawEnd1 = raw"foo \u12"
+  val badInters3 = s"""foo \unope that's wrong""" 
+  val badInterRaw3 = raw"""foo \unope that's wrong"""
+}

test/files/run/t3220-213.check

@@ -1,21 +1,21 @@
-t3220-213.scala:9: warning: Unicode escapes in triple quoted strings and raw interpolations are deprecated, use the literal character instead
+t3220-213.scala:9: warning: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
   def inTripleQuoted = """\u000A"""
-                       ^
-t3220-213.scala:42: warning: Unicode escapes in triple quoted strings and raw interpolations are deprecated, use the literal character instead
+                          ^
+t3220-213.scala:42: warning: Unicode escapes in triple quoted strings are deprecated, use the literal character instead
       "tab unicode escape in triple quoted string" -> """tab\u0009tab""",
-                                                      ^
-t3220-213.scala:10: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14
+                                                            ^
+t3220-213.scala:10: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14. Use the literal character instead.
   def inInterpolation = raw"\u000A"
                             ^
-t3220-213.scala:11: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14
+t3220-213.scala:11: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14. Use the literal character instead.
   def inTripleQuotedInterpolation = raw"""\u000A"""
                                           ^
-t3220-213.scala:43: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14
+t3220-213.scala:43: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14. Use the literal character instead.
       "tab unicode escape in single quoted raw interpolator" -> raw"tab\u0009tab",
-                                                                    ^
-t3220-213.scala:44: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14
+                                                                       ^
+t3220-213.scala:44: warning: Unicode escapes in raw interpolations are deprecated as of scala 2.13.1, and will be removed in scala 2.14. Use the literal character instead.
       "tab unicode escape in triple quoted raw interpolator" -> raw"""tab\u0009tab"""
-                                                                      ^
+                                                                         ^
 supported
 literals that result in tab	tab:
 literal tab in single quoted string