| Header | Implementation | Tests | Notes |
|---|---|---|---|
| <assert.h> | ❌ | ❌ | |
| <complex.h> | ❌ | ❌ | |
| <ctype.h> | ✔️ | ❌ | |
| <errno.h> | ❌ | ❌ | |
| <fenv.h> | ❌ | ❌ | |
| <float.h> | ✅ | ❌ | GCC provided |
| <inttypes.h> | ❌ | ❌ | |
| <iso646.h> | ✅ | ❌ | GCC provided |
| <limits.h> | ✅ | ❌ | GCC provided |
| <locale.h> | ❌ | ❌ | |
| <math.h> | ❌ | ❌ | |
| <setjmp.h> | ❌ | ❌ | |
| <signal.h> | ❌ | ❌ | |
| <stdalign.h> | ✅ | ❌ | GCC provided |
| <stdarg.h> | ✅ | ❌ | GCC provided |
| <stdatomic.h> | ✅ | ❌ | GCC provided |
| <stdbool.h> | ✅ | ❌ | GCC provided |
| <stddef.h> | ✅ | ❌ | GCC provided |
| <stdint.h> | ✅ | ❌ | GCC provided |
| <stdio.h> | 🔷 | ❌ | |
| <stdlib.h> | 🔷 | ❌ | |
| <string.h> | ✔️ | 🔷 | some omitted |
| <tgmath.h> | ❌ | ❌ | |
| <threads.h> | ❌ | ❌ | |
| <time.h> | ❌ | ❌ | |
| <uchar.h> | ❌ | ❌ | |
| <wchar.h> | ❌ | ❌ | |
| <wctype.h> | ❌ | ❌ |
❌ - not implemented
🔷 - in progress
✅ - compiler provided
✔️ - implemented