Hey im also using g++, got a few warnings from juce code:
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp: In static member function 'static void juce::AiffAudioFormatReader::copySampleData(unsigned int, bool, int* const*, int, int, const void*, int, int)':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|619 col 25| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else ReadHelper<AudioData::Int32, AudioData::Int32, Endianness>::read (destSamples, startOffsetInDestBuffer, numDestChannels, sourceData, numChannels, numSamples); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|619 col 215| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else ReadHelper<AudioData::Int32, AudioData::Int32, Endianness>::read (destSamples, startOffsetInDestBuffer, numDestChannels, sourceData, numChannels, numSamples); break;^M
|| ^~~~~
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp: In member function 'virtual void juce::MemoryMappedAiffReader::getSample(juce::int64, float*) const':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|872 col 29| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::LittleEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|872 col 168| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::LittleEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|884 col 29| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::BigEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|884 col 165| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::BigEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~~
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp: In member function 'virtual void juce::MemoryMappedAiffReader::readMaxLevels(juce::int64, juce::int64, juce::Range<float>*, int)':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|910 col 25| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else scanMinAndMax<AudioData::Int32> (startSampleInFile, numSamples, results, numChannelsToRead); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_AiffAudioFormat.cpp|910 col 147| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else scanMinAndMax<AudioData::Int32> (startSampleInFile, numSamples, results, numChannelsToRead); break;^M
|| ^~~~~
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/oggvorbis/libvorbis-1.3.2/lib/vorbisfile.c: In function 'int juce::OggVorbisNamespace::ov_pcm_seek_page(juce::OggVorbisNamespace::OggVorbis_File*, juce::OggVorbisNamespace::ogg_int64_t)':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/oggvorbis/libvorbis-1.3.2/lib/vorbisfile.c|1566 col 10| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| }else^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/oggvorbis/libvorbis-1.3.2/lib/vorbisfile.c|1568 col 11| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| (void) result;^M
|| ^
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp: In static member function 'static void juce::WavAudioFormatReader::copySampleData(unsigned int, bool, int* const*, int, int, const void*, int, int)':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1200 col 25| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else ReadHelper<AudioData::Int32, AudioData::Int32, AudioData::LittleEndian>::read (destSamples, startOffsetInDestBuffer, numDestChannels, sourceData, numChannels, numSamples); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1200 col 228| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else ReadHelper<AudioData::Int32, AudioData::Int32, AudioData::LittleEndian>::read (destSamples, startOffsetInDestBuffer, numDestChannels, sourceData, numChannels, numSamples); break;^M
|| ^~~~~
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp: In member function 'virtual void juce::MemoryMappedWavReader::getSample(juce::int64, float*) const':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1518 col 25| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::LittleEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1518 col 164| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else ReadHelper<AudioData::Float32, AudioData::Int32, AudioData::LittleEndian>::read (dest, 0, 1, source, 1, num); break;^M
|| ^~~~~
|| ../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp: In member function 'virtual void juce::MemoryMappedWavReader::readMaxLevels(juce::int64, juce::int64, juce::Range<float>*, int)':
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1543 col 25| warning: this 'else' clause does not guard... [-Wmisleading-indentation]
|| else scanMinAndMax<AudioData::Int32> (startSampleInFile, numSamples, results, numChannelsToRead); break;^M
|| ^~~~
/home/linuxUser/code/juce_Project/Builds/LinuxMakefile/../../JuceLibraryCode/modules/juce_audio_formats/codecs/juce_WavAudioFormat.cpp|1543 col 147| note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
|| else scanMinAndMax<AudioData::Int32> (startSampleInFile, numSamples, results, numChannelsToRead); break;^M
|| ^~~~~
No Erros, just warning, but this good feeling of compiling my software without any errors and warnings is a little smaller with those errors! 
Greetz equinox