| 8 | 8 | Sometimes programs are written to use functions before declaring them. This has not been correct ever since the introduction of the 1999 version of the C standard decades ago, but because it was allowed by the earlier 1989 C standard many C99 compilers still allowed this with a warning. But it can cause programs to crash or behave incorrectly on ARM processors, therefore to avoid problems on Apple Silicon Macs, the version of clang in included with Xcode 12 and later considers this to be an error. This causes some ports to fail to build. Worse, many configure tests have this problem, but when they fail, it doesn't cause configure to immediately fail and tell you that; instead, configure just makes wrong determinations about your system. In the best case, the build still succeeds and works fine. Or, the build fails with a bizarre error later. Or the build succeeds but is wrong. |
