Enforcing string start/end check. See #1687

app/src/processing/app/preproc/PdePreprocessor.java

@@ -327,6 +327,25 @@ public class PdePreprocessor {
     return functionMatches;
   }
 
+  private boolean isStartOrEndOfString(char p[], int index) {
+    if (p[index] != '\"') {
+      return false;
+    }
+
+    if (index == 0) {
+      return true;
+    }
+
+    if (p[index - 1] == '\\') {
+      return false;
+    }
+
+    if (index - 2 >= 0 && p[index - 2] == '\\') {
+      return true;
+    }
+
+    return true;
+  }
 
   /**
    * Replace all commented portions of a given String as spaces.
@@ -338,7 +357,7 @@ public class PdePreprocessor {
     int index = 0;
     boolean insideString = false;
     while (index < p.length) {
-      if (p[index] == '\"') {
+      if (isStartOrEndOfString(p, index)) {
         insideString = !insideString;
       }
       // for any double slash comments, ignore until the end of the line

app/test/processing/app/preproc/StringWithCcomment.ino

@@ -1,6 +1,10 @@
 void setup() {
   // put your setup code here, to run once:
+  // "comment with a double quote
+  /* \" other comment with double quote */
   Serial.println("Accept: */*");
+  Serial.println("Accept: \" */*");
+  Serial.println("Accept: \\"); // */*");
 }
 
 void loop() {

app/test/processing/app/preproc/StringWithCcomment.stripped.ino

@@ -1,5 +1,9 @@
 void setup() {
    
+   
+   
+  Serial.println( );
+  Serial.println( );
   Serial.println( );  
 }