Attempt to remove travis+clang+ccache warnings.

.travis.yml

@@ -9,6 +9,7 @@ compiler:
 env:
     global:
         - secure: "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"
+        - CCACHE_CPP2=yes
 
 before_install:
     - echo -n | openssl s_client -connect https://scan.coverity.com:443 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | sudo tee -a /etc/ssl/certs/ca-

CMakeLists.txt

@@ -29,6 +29,15 @@ configure_file(
 	"${PROJECT_BINARY_DIR}/config.h"
 	)
 
+if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+	set(CLANG 1)
+endif()
+
+if (CCACHE_FOUND AND CLANG)
+	add_definitions(-Qunused-arguments -fcolor-diagnostics)
+endif()
+
+
 IF ( WIN32 )
     MESSAGE ( STATUS "Setting MSVC MT switches")
     SET (