kc3-lang/libjpeg-turbo

2019-10-24T01:50:35

AppVeyor: Use MinGW-builds instead of MSYS2 MinGW ... to avoid backward compatibility issues with GCC 4-6 MinGW toolchains. Apparently GCC 7+ MinGW toolchains introduce a link-time dependency with internal MinGW CRT functions that are meant to provide compatibility with Microsoft's Universal CRT (ucrt) library, but those internal functions are not available in GCC 4-6 MinGW toolchains. This made it impossible to use the official builds of libjpeg.a and libturbojpeg.a with GCC 4-6 MinGW toolchains (a fatal link error-- "undefined reference to '__imp___acrt_iob_func'"-- occurred.) This problem was not immediately apparent after switching to the MSYS2 implementation of MinGW (d6d7b539682abb50b04207abd21726573c0fb845) because, for a while, MSYS2 was still using GCC 5 and 6. Refer to libjpeg-turbo/libjpeg-turbo#382