Is it possible to display compiler warnings in Arduino? - arduino

Question

I would like the Arduino IDE to display compiler warnings, and I would rather not have to compile once in the terminal for warnings, and again through Arduino to generate the hex file.
Holding down the shift key while clicking the "Verify" button shows intermediate commands, but none of their output. Is this possible without hacking the Arduino IDE?

Answer 1

Using Arduino IDE 1.6.4 and newer, the warning level can be easily adjusted via menu File → Preferences → Compiler warnings:.
Using Arduino AVR Boards, the compiler flags set via this option are:
"None": -w
"Default":
"More: -Wall
"All": -Wall -Wextra

Answer 2

The default compiler command line options include -w, which suppresses warnings, but you can change that by editing C:\Program Files (x86)\Arduino\hardware\arduino\avr\platform.txt. Since the libraries might contain warnings, but I want -Werror for myself, I removed the -w options, and then added to my source code:
#pragma GCC diagnostic error "-Wall"
#pragma GCC diagnostic error "-Werror"

Answer 3

This feature has been added to the latest Arduino source code, although is not yet in a released version (see Showing compilation warnings when verbose output is enabled).
It's planned to be included in the next major Arduino IDE release (version 1.0) which is currently planned for release at the end of October 2011. The current release candidate has this fix (as of October 25, 2011).
To enable compiler warnings from within the Arduino IDE, open menu File → Preferences, and then tick Show verbose output during: compilation and/or Show verbose output during: upload.

Answer 4

Most answers here seem to be outdated. From Arduino.app 1.5 onwards you must find the file preferences.txt (https://www.arduino.cc/en/Hacking/Preferences) and change the line compiler.warning_level=none to compiler.warning_level=all IMPORTANT: Quit Arduino first, edit, then start the IDE again.

Answer 5

The feature as described by Matthew, not only displays the warnings, but a lot of distracting information on how the compiler was called as well.
See the addendum to my question Have the Arduino IDE set compiler warnings to error. It implements the changes to the Arduino script:
-export PATH="${APPDIR}/java/bin:${PATH}"
+export ORGPATH="${APPDIR}/java/bin:${PATH}"
+export PATH="${APPDIR}/extra:${ORGPATH}"
And make the extra/avr-g++:
#! /usr/bin/env python
import os
import sys
import subprocess
checklibpat = [
'SoftwareSerial',
'GSM_GPRS',
]
werr = '-Werror'
wall = '-Wall'
cmd = ['avr-g++'] + sys.argv[1:]
os.environ['PATH'] = os.environ['ORGPATH']
fname = sys.argv[-2][:]
extend = False
warn = False
if cmd[-2].startswith('/tmp'):
extend = True
warn = True
if not extend:
for l in checklibpat:
if l in cmd[-2]:
warn = True
break
if warn:
#print len(fname), list(fname)
for i, c in enumerate(cmd):
if c == '-w':
cmd[i] = wall
break
if extend:
cmd.insert(1, werr)
## to enable deprecated stuff (Print.cpp) with gcc 4.7.0
#cmd.insert(1, '-D__PROG_TYPES_COMPAT__=1')
subprocess.call(cmd)
Comment out extend = True if you do not want the compiler to interpret warnings in your source as errors.