commit bea1c027ed5c863ae21df895d62d7a519bc24eaf
Author: Adriaan de Groot <groot@kde.org>
Date:   Sat Aug 10 21:54:33 2019 +0200

    Fix build with CMake 3.15
    
    Summary:
     - The build flags for the C part of the library overwrite the
       compile flags for C++, in particular, they add -std=c99
       to the C++ compilation.
     - The C parts get auto-mocced (!) which generates a C++
       file (although it's empty), which then gets compiled with
       the C flags (and weird -std= setting).
     - For clang, that leads to a build failure.
    
    So switch out some things:
    
     - Build the C parts as an OBJECT library,
     - Don't apply the C flags to anything but that OBJECT library,
     - and don't automoc C code.
    
    Test Plan: It now builds when CMake 3.15.2 is used.
    
    Reviewers: leinir
    
    Differential Revision: https://phabricator.kde.org/D23076
diff --git src/qtquick/karchive-rar/CMakeLists.txt src/qtquick/karchive-rar/CMakeLists.txt
index 3928dfd..022ecd1 100644
--- src/qtquick/karchive-rar/CMakeLists.txt
+++ src/qtquick/karchive-rar/CMakeLists.txt
@@ -2,10 +2,6 @@ project(karchive-rar)
 
 find_package(ZLIB)
 
-if (UNIX OR MINGW)
-    add_compile_options(-std=gnu99 -fomit-frame-pointer -D_FILE_OFFSET_BITS=64 -fPIC)
-endif (UNIX OR MINGW)
-
 set(unarr_SRCS
     unarr/rar/uncompress-rar.c
     unarr/rar/huffman-rar.c
@@ -31,7 +27,14 @@ set(karchive_rar_SRCS
     KRarFileEntry.cpp
 )
 
-add_library(karchive-rar STATIC ${karchive_rar_SRCS} ${unarr_SRCS})
+add_library(karchive-c-unarr OBJECT ${unarr_SRCS})
+if (UNIX OR MINGW)
+    target_compile_options(karchive-c-unarr PRIVATE -std=gnu99 -fomit-frame-pointer -D_FILE_OFFSET_BITS=64 -fPIC)
+    set_property(TARGET karchive-c-unarr PROPERTY AUTOMOC OFF)
+endif (UNIX OR MINGW)
+
+
+add_library(karchive-rar STATIC ${karchive_rar_SRCS} $<TARGET_OBJECTS:karchive-c-unarr>)
 target_link_libraries(karchive-rar
     PUBLIC KF5::Archive
 )