On some platforms there is a parsing error for some complex numbers. Example:

_Complex v = 3.0 + 1.0iF;

There is a parsing error when loading stdatomic.h.

Tigress is slow on huge programs.

_thread is incorrectly put after the identifier in declarations instead of before. This is a regression: it works in Tigress 3.3.3 but fails in 4.x.

Tigress fails on this code:

#include<stdio.h>
typedef int __attribute__ ((mode (__pointer__))) intptr_t;

Variable length arrays in structures are supported by gcc but are rejected by Clang. Tigress currently fails on this code and we are unlikely to support it in the future:

void foo(int n) {
   struct S {int i[n];}
}

If you see syntax errors while loading standard include files, make sure you've included tigress.h at the top of every file. Example:

/usr/include/bits/mathcalls-helper-functions.h[21:12-28] : syntax error

Tigress supports the C99 language. Depending on your compiler, you may have to add a switch (such as -std=c99 for gcc) to indicate this.