Fix build in Ubuntu 18.04 clang 6.0.0 (#276)

* Fix build in Ubuntu 18.04 clang 6.0.0

* Globally allow double-promotion instead of on a case-by-case basis

cmake/k4aCompilerFlags.cmake

@@ -24,6 +24,7 @@ if ("${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
     list(APPEND CLANG_ALL_WARNINGS "-Wno-documentation-unknown-command") # Allow undocumented documentation commands used by doxygen
     list(APPEND CLANG_ALL_WARNINGS "-Wno-covered-switch-default") # Allow default: in switch statements that cover all enum values
     list(APPEND CLANG_ALL_WARNINGS "-Wno-unreachable-code-break") # Allow break even if it is unreachable
+    list(APPEND CLANG_ALL_WARNINGS "-Wno-double-promotion") # Allow floats to be promoted to doubles. Needed for isnan() on some systems
     if (NOT (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS "5.0.0"))
         # Added in clang 5
         list(APPEND CLANG_ALL_WARNINGS "-Wno-zero-as-null-pointer-constant") # Allow zero as nullptr
@@ -46,4 +47,4 @@ elseif ("${CMAKE_C_COMPILER_ID}" STREQUAL "MSVC")
     add_compile_options(${MSVC_WARNINGS_AS_ERRORS})
 else()
     message(FATAL_ERROR "Unknown C++ compiler: ${CMAKE_CXX_COMPILER_ID}")
-endif()
+endif()

src/allocator/allocator.c

@@ -351,15 +351,6 @@ void capture_set_imu_image(k4a_capture_t capture_handle, k4a_image_t image_handl
     capture_set_ir_image(capture_handle, image_handle);
 }
 
-// On Ubuntu 16.04 this works without warnings, but on Ubuntu 18.04 isnan actually
-// takes a long double, we get a double-promotion warning here.  Unfortunately,
-// isnan has an implementation-defined argument type, so there's not a specific
-// type we can cast it to in order to avoid clang's precision warnings, so we
-// just need to suppress the warning.
-#ifdef __clang__
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdouble-promotion"
-#endif
 void capture_set_temperature_c(k4a_capture_t capture_handle, float temperature_c)
 {
     RETURN_VALUE_IF_HANDLE_INVALID(VOID_VALUE, k4a_capture_t, capture_handle);
@@ -369,10 +360,6 @@ void capture_set_temperature_c(k4a_capture_t capture_handle, float temperature_c
     capture->temperature_c = temperature_c;
 }
 
-#ifdef __clang__
-#pragma clang diagnostic pop
-#endif
-
 float capture_get_temperature_c(k4a_capture_t capture_handle)
 {
     RETURN_VALUE_IF_HANDLE_INVALID(NAN, k4a_capture_t, capture_handle);