C compiler's default standard which is C17 (a `bug-fix' of C11) --

Use a standard that is at most C17.  The

intention is to allow legacy packages to still be installed when

later C standards become the default, including packages

using new keywords as identifiers or with K&R-style function

declarations.  This will use C17 if available, falling back

Use the C90 (aka C89) standard.  (As that standard

did not require compilers to identify that version, all we can

verify is that the compiler does not claim to be using a later

standard.  It may accept C99 features -- for example

Use the C99 standard. This should be rarely

needed -- it avoids the few new features of C11/C17 which can

be useful if a package assumes them if C17 is specified and

Use C23 (or in future, later).  Compiler/library

support for C23 is still being implemented, but

from 15.0.0 and GCC from 13 have quite extensive support.

needs to include that file itself.  Installation of a package with

which obfuscate the actual compile commands

calling BLAS/LAPACK routines from C/C++ is the default even for

packages.  (Unless perhaps packages call Fortran code from C/C++

's headers and without allowing for these

mis-compilation when interfacing with Fortran (

new definition causes compiler warnings with static initializers

Using the new definition from C++ depends on compiler extensions

supporting C features that have not been incorporated into the C++

: this may result in C++ compiler warnings but

these have been worked around for recent versions of common

It is intended to change the inclusion of header

files, warning about invalid email addresses and (some) invalid

for exceptionally fast or slow platforms.

It now applies to checking PDF and HTML versions of the manuals,

Non-interactive debugger invocations can be trapped by

been deprecated in macOS 13 and is a known security risk.

now reports (on all platforms) if their use

compiled into the package is platform-dependent.]

reports the C and Fortran compilers used to build

It reports the OS in use (if known, as given by