Compiler warnings "unknown escape characters" on Windows

[PaulStoffregen]

Seems like 8217efd did not fully address all the Windows pathnames.

I tested today with "arduino-PR-beta1.9-BUILD-26".

To reproduce problem, set Compiler Warnings to "All" in File > Preferences. Then compile this sketch for Arduino Zero.

void setup() {
  Serial.begin(9600);
}

void loop() {
  dosomething();
  delay(1000);
}

void dosomething() {
  Serial.println("Hello world");
}

The compiler warnings scroll by quickly. You may need to scroll back up to see them. Here's a screenshot:

[PaulStoffregen]

Here's the last several lines from dosomething.ino.cpp in the temp build folder.

Some have all the Windows backslash characters properly escaped, but others have only the first one escaped. :-(

extern uint32_t UHD_Pipe_Read(uint32_t ul_pipe, uint32_t ul_size, uint8_t* data);
extern void UHD_Pipe_Write(uint32_t ul_pipe, uint32_t ul_size, uint8_t* data);
extern void UHD_Pipe_Send(uint32_t ul_pipe, uint32_t ul_token_type);
extern uint32_t UHD_Pipe_Is_Transfer_Complete(uint32_t ul_pipe, uint32_t ul_token_type);


}
# 132 "C:\\Users\\me\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\samd\\1.6.15\\cores\\arduino/Arduino.h" 2
# 2 "C:\\Users\\me\\AppData\\Local\\Temp\\arduino_build_552271\\sketch\\dosomething.ino.cpp" 2
# 1 "C:\\Users\\me\\Documents\\Arduino\\dosomething\\dosomething.ino"
# 1 "C:\\Users\\me\\Documents\\Arduino\\dosomething\\dosomething.ino"
void setup() {
  Serial.begin(9600);
}

#line 5 "C:\\Users\me\Documents\Arduino\dosomething\dosomething.ino"
extern "C" void loop();
#line 10 "C:\\Users\me\Documents\Arduino\dosomething\dosomething.ino"
void dosomething();
#line 5 "C:\\Users\me\Documents\Arduino\dosomething\dosomething.ino"
void loop() {
  dosomething();
  delay(1000);
}

void dosomething() {
  Serial.println("hello world");
}

[matthijskooijman]

@facchinm, why does that commit also change a bunch of cygwin dlls? Doesn't seem related to the subject of the commit?