Setting Android ABI level for all architectures

My goal is to build an Android application with QtCreator by using cmake as the build system. I use the following basic settings:

• Android ABI level 30
• iconv to convert between character sets

Here a small code excerpt which does not compile with an Android ABI level less then 29:

#include <iconv.h>

/**
 * @brief EncodeTo convert into another character set.
 *
 * This method takes a string and converts it into another character set.
 *
 * @param buf   A pointer to a buffer large enough to hold the result.
 * @param len   The length of the buffer \p buf.
 * @param str   A pointer to a string. The content will be converted.
 * @param from  The name of the character set in \p str.
 * @param to    The name of the target charcter set.
 * @return The pointer \p buf. This buffer is filled up to the length of \p str
 * or the zero byte. Whichever comes first.
 */
char *EncodeTo(char* buf, size_t *len, const string& str, const string& from, const string& to)
{
	if (!buf || str.empty())
		return 0;

    iconv_t cd = iconv_open(from.c_str(), to.c_str());

	if (cd == (iconv_t) -1)
		return nullptr;

	char *in_buf = (char *)str.c_str();
	size_t in_left = str.length() - 1;

	char *out_buf = buf;
	size_t out_left = *len - 1;

	do
	{
		if (iconv(cd, &in_buf, &in_left, &out_buf, &out_left) == (size_t) -1)
			return nullptr;
	}
	while (in_left > 0 && out_left > 0);

	*out_buf = 0;
	iconv_close(cd);
	*len = out_buf - buf;
	return buf;
}

In the build settings of QtCreator, at the section cmake, I set the ANDROID_PLATFORM to android-30. I set the same to ANDROID_NDK_PLATFORM. Then I set the QT_ANDROID_BUILD_ALL_ABIS to ON.

In the section Create Android-APK I set Android build platform-SDK also to android-30.

Also in the section Build environment I set ANDROID_NDK_PLATFORM to android-30.

Then, after cmake was running again and created the build files, I start the compilation of the C++ code. You can take any C++ example for Android to try this as long as it contains some code only available at a level higher then 27.

The main architecture, which is x86_64 in my case, build quite fine, but the other architectures not. The reason for this is that only for the main architecture android-30 is set and all others use the minimal ABI level 23.

After a closer look to the cmake macros I found out that the ANDROID_PLATFORM is not set for the architectures. I found a solution for this:

• Go to the directory where Qt is installed (e.g. /opt/Qt/6.5.x)
• With a text editor open the file android_x86_64/lib/cmake/Qt6Core/Qt6AndroidMacros.cmake.
• Search for a function called _qt_internal_configure_android_multiabi_target. You'll find it around line 1180.

Look for this code sequence:

if(DEFINED QT_HOST_PATH_CMAKE_DIR) 
    list(APPEND extra_cmake_args "-DQT_HOST_PATH_CMAKE_DIR=${QT_HOST_PATH_CMAKE_DIR}") 
endif() 

if(CMAKE_MAKE_PROGRAM) 
    list(APPEND extra_cmake_args "-DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}")
endif()

Add the following lines:

if(ANDROID_PLATFORM) 
    list(APPEND extra_cmake_args "-DANDROID_PLATFORM=${ANDROID_PLATFORM}")
endif()

Then compile again. Now it should work.

This error exists at least from version 6.5.0 on. It is also present in Qt 6.5.3.

A.T.