Build failure due to implicit declaration of functions

[ryandesign]

scalapack 2.1.0 fails to build when implicit declaration of functions is an error. (This is the default behavior of the clang included with Apple's Xcode 12 or later and can also be achieved on other compilers by adding -Werror=implicit-function-declaration to CFLAGS.) grepping the build log for these errors, they are:

BLACS/SRC/igsum2d_.c:153:7: error: implicit declaration of function 'BI_imvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/igsum2d_.c:166:6: error: implicit declaration of function 'BI_ivmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/sgsum2d_.c:154:7: error: implicit declaration of function 'BI_smvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/sgsum2d_.c:167:6: error: implicit declaration of function 'BI_svmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/dgsum2d_.c:154:7: error: implicit declaration of function 'BI_dmvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/dgsum2d_.c:167:6: error: implicit declaration of function 'BI_dvmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/cgsum2d_.c:154:7: error: implicit declaration of function 'BI_smvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/cgsum2d_.c:169:6: error: implicit declaration of function 'BI_svmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/zgsum2d_.c:156:7: error: implicit declaration of function 'BI_dmvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/zgsum2d_.c:171:6: error: implicit declaration of function 'BI_dvmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/igamx2d_.c:199:7: error: implicit declaration of function 'BI_imvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/igamx2d_.c:278:6: error: implicit declaration of function 'BI_ivmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/igamx2d_.c:280:16: error: implicit declaration of function 'BI_TransDist' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/sgamx2d_.c:202:7: error: implicit declaration of function 'BI_smvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/sgamx2d_.c:281:6: error: implicit declaration of function 'BI_svmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/sgamx2d_.c:283:16: error: implicit declaration of function 'BI_TransDist' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/dgamx2d_.c:202:7: error: implicit declaration of function 'BI_dmvcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/dgamx2d_.c:281:6: error: implicit declaration of function 'BI_dvmcopy' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
BLACS/SRC/dgamx2d_.c:283:16: error: implicit declaration of function 'BI_TransDist' is invalid in C99 [-Werror,-Wimplicit-function-declaration]

This was reported to MacPorts here: https://trac.macports.org/ticket/62567

[eli-schwartz]

Clang and GCC are both making these fatal errors by default.

Note that implicit function declarations is legal in the c89 standard, but removed in the next version without a deprecation period because it was so bad.

It's not a cosmetic problem, this is a big cause of crashes, especially on architectures other than amd64.

[eli-schwartz]

Also reported downstream at https://bugs.gentoo.org/898290

[drew-parsons]

This is causing build failure of debian packages now, after dpkg 1.22.6 switched on -Werror=implicit-function-declaration. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1066328