Case 61: Global Variable Added¶
| Field | Value |
|---|---|
| Verdict | 🟢 COMPATIBLE |
| Category | Addition (Compatible) |
| Platforms | Linux, macOS |
| Flags | — |
Detected ChangeKinds |
var_added |
| Source files | browse on GitHub |
Category: Symbol API | Verdict: COMPATIBLE
What this case is about¶
v1 exports lib_version. v2 adds a new global variable lib_build_number.
All existing symbols are unchanged — this is a purely additive change.
Why this is compatible¶
- Existing binaries never reference
lib_build_number, so it doesn't affect them. - New consumers can optionally use the new variable.
- No layout, offset, or size changes.
What abicheck detects¶
VAR_ADDED: A new global variable symbol appeared in.dynsym.
Overall verdict: COMPATIBLE
How to reproduce¶
gcc -shared -fPIC -g bad.c -o libbad.so
gcc -shared -fPIC -g good.c -o libgood.so
nm -D libgood.so | grep lib_build_number # → D lib_build_number
python3 -m abicheck.cli dump libbad.so -o /tmp/v1.json
python3 -m abicheck.cli dump libgood.so -o /tmp/v2.json
python3 -m abicheck.cli compare /tmp/v1.json /tmp/v2.json
# → COMPATIBLE: VAR_ADDED
References¶
Source files¶
See also: Examples overview · All COMPATIBLE cases · Category: Addition (Compatible).