Lexer: Don't split an operator '.<' from '.<#placeholder#>'

'.<#placeholder#>' is actually an unresolved reference where the name is
an editor placeholder, not the operator '.<' followed by #placeholder#>.

rdar://problem/28457876

Author: bitjammer

lib/Parse/Lexer.cpp

@@ -678,6 +678,19 @@ static bool isRightBound(const char *tokEnd, bool isLeftBound,
   }
 }
 
+static bool rangeContainsPlaceholderEnd(const char *CurPtr,
+                                        const char *End) {
+  while (CurPtr++ < End - 1) {
+    if (*CurPtr== '\n') {
+      return false;
+    }
+    if (CurPtr[0] == '#' && CurPtr[1] == '>') {
+      return true;
+    }
+  }
+  return false;
+}
+
 /// lexOperatorIdentifier - Match identifiers formed out of punctuation.
 void Lexer::lexOperatorIdentifier() {
   const char *TokStart = CurPtr-1;
@@ -697,6 +710,10 @@ void Lexer::lexOperatorIdentifier() {
     // started with a '.'.
     if (*CurPtr == '.' && *TokStart != '.')
       break;
+    if (Identifier::isEditorPlaceholder(StringRef(CurPtr, 2)) &&
+        rangeContainsPlaceholderEnd(CurPtr + 2, BufferEnd)) {
+      break;
+    }
   } while (advanceIfValidContinuationOfOperator(CurPtr, BufferEnd));
 
   if (CurPtr-TokStart > 2) {

test/IDE/structure_object_literals.swift

@@ -13,3 +13,26 @@ struct I: _ExpressibleByImageLiteral {
 
 // CHECK: <gvar>let <name>z</name>: I? = <object-literal-expression>#<name>imageLiteral</name>(<arg><name>resourceName</name>: "hello.png"</arg>)</object-literal-expression></gvar>
 let z: I? = #imageLiteral(resourceName: "hello.png")
+
+func before() {}
+// CHECK-AFTER: <ffunc>func <name>before()</name> {}</ffunc>
+_ = .<#line#>
+_ = 1<#line
+_ = 1<#line#>
+_ = a.+<#file#>
+_ = x.<; <# #>;
+_ = 2.<#file(2)
+<##>
+x <##> y
+_ = .<#placeholder#>
+_ = #colorLiteral(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0)
+
+.<# place #> #fileLiteral(resourceName: "sdfds") .<# holder #>
+.<##>#imageLiteral(resourceName: <# name #>)x.<##>
+
+func after() {}
+// CHECK-AFTER: _ = <object-literal-expression>#<name>colorLiteral</name>(<arg><name>red</name>: 0.0</arg>, <arg><name>green</name>: 0.0</arg>, <arg><name>blue</name>: 0.0</arg>, <arg><name>alpha</name>: 1.0</arg>)</object-literal-expression>
+// CHECK-AFTER: .<# place #> <object-literal-expression>#<name>fileLiteral</name>(<arg><name>resourceName</name>: "sdfds"</arg>)</object-literal-expression> .<# holder #>
+// CHECK-AFTER: .<##><object-literal-expression>#<name>imageLiteral</name>(<arg><name>resourceName</name>: <# name #></arg>)</object-literal-expression>x.<##>
+// CHECK-AFTER: <ffunc>func <name>after()</name> {}</ffunc>
+