From 75cfd808aec7cd94ab3e2c13ffd4821887de6ddd Mon Sep 17 00:00:00 2001
From: Som Snytt <som.snytt@gmail.com>
Date: Wed, 23 Mar 2016 11:23:41 -0700
Subject: SI-9314 No warn on ${nonid}

Use the sym test on an expr that happens to be a subset of
idents and is not in scope. Other `${ operator_* }` warn.
---
 src/compiler/scala/tools/nsc/typechecker/Typers.scala | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 1b55618691..facb695447 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -105,7 +105,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
   // that are turned private by typedBlock
   private final val SYNTHETIC_PRIVATE = TRANS_FLAG
 
-  private final val InterpolatorCodeRegex  = """\$\{(.*?)\}""".r
+  private final val InterpolatorCodeRegex  = """\$\{\s*(.*?)\s*\}""".r
   private final val InterpolatorIdentRegex = """\$[$\w]+""".r // note that \w doesn't include $
 
   abstract class Typer(context0: Context) extends TyperDiagnostics with Adaptation with Tag with PatternTyper with TyperContextErrors {
@@ -5211,14 +5211,18 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
         def maybeWarn(s: String): Unit = {
           def warn(message: String)         = context.warning(lit.pos, s"possible missing interpolator: $message")
           def suspiciousSym(name: TermName) = context.lookupSymbol(name, _ => true).symbol
-          val suspiciousExpr                = InterpolatorCodeRegex findFirstMatchIn s
+          val suspiciousExprs               = InterpolatorCodeRegex findAllMatchIn s
           def suspiciousIdents              = InterpolatorIdentRegex findAllIn s map (s => suspiciousSym(TermName(s drop 1)))
-
-          if (suspiciousExpr.nonEmpty)
-            suspiciousExpr filter (!_.group(1).trim.isEmpty) foreach (_ =>
+          def isCheapIdent(expr: String)    = (Character.isJavaIdentifierStart(expr.charAt(0)) &&
+                                               expr.tail.forall(Character.isJavaIdentifierPart))
+          def warnableExpr(expr: String)    = !expr.isEmpty && (!isCheapIdent(expr) || isPlausible(suspiciousSym(TermName(expr))))
+
+          if (suspiciousExprs.nonEmpty) {
+            val exprs = (suspiciousExprs map (_ group 1)).toList
+            // short-circuit on leading ${}
+            if (!exprs.head.isEmpty && exprs.exists(warnableExpr))
               warn("detected an interpolated expression") // "${...}"
-            )
-          else
+          } else
             suspiciousIdents find isPlausible foreach (sym => warn(s"detected interpolated identifier `$$${sym.name}`")) // "$id"
         }
         lit match {
-- 
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