To make a conforming C compiler, someone has to buy the ISO C standard (208 CHF), which other folks will then spend development resources in creating C compilers that obey said standard.
The biggest open source compilers, clang and GCC, only keep being up to date with ISO C, because of the money from IBM, Red-Hat, Apple, ARM, Intel, Green-Hills,... place in assigning company resources to work on them.
To make a conforming C compiler, someone has to buy the ISO C standard (208 CHF), which other folks will then spend development resources in creating C compilers that obey said standard.
The biggest open source compilers, clang and GCC, only keep being up to date with ISO C, because of the money from IBM, Red-Hat, Apple, ARM, Intel, Green-Hills,... place in assigning company resources to work on them.