Git Has a Variable Named false_but_the_compiler_does_not_know_it
The article discusses a peculiar variable in Git's source code named 'false_but_the_compiler_does_not_know_it_'. This variable is used in a macro to prevent the compiler from optimizing out certain code, which could lead to false positives during compilation. The trick allows Git to maintain code functionality while avoiding compiler warnings about unreachable code.
- ▪The variable 'false_but_the_compiler_does_not_know_it_' is initialized to 0 and never modified in Git's codebase.
- ▪It is used in a macro called NOT_CONSTANT to prevent compiler optimizations that could trigger warnings.
- ▪This approach allows Git to handle specific code scenarios without raising unnecessary compiler errors.
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| Original publisher | Hacker News (Newest) |
| Canonical URL | https://blog.codingconfessions.com/p/false-but-the-compiler-does-not-know-it |
| Publication time | Wed, 03 Jun 2026 12:26:57 +0000 |
| Retrieval time | 2026-06-03T12:42:07.659Z |
| Last seen | 2026-06-03T12:42:07.659Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | tpPWojtgSkfD |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
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| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
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| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
Why Git Has a Variable Named false_but_the_compiler_does_not_know_itA small C trick that keeps Clang from flagging valid code as unreachableAbhinav UpadhyayJun 03, 2026ShareToday, in weird C code tricks, I want to show you a small example from Git’s source code.Recently, I was poking around the Git source when a directory name caught my eye, it was named “compiler-tricks”. I thought, “This is a promising name, let’s see what’s inside of it”.Inside this directory, there was a file called not-constant.c, and the whole file contained just this:#include <git-compat-util.h> int false_but_the_compiler_does_not_know_it_ = 0;The variable name made me curious.
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