languageversion

Languageversion, or language version, is a configuration value used by compilers and interpreters to determine which edition of a programming language to apply when compiling code. It selects the set of syntax rules, features, semantics, and sometimes diagnostic behavior that the compiler should use. By isolating language features from runtimes or libraries, projects can adopt newer language capabilities while maintaining compatibility with older code or toolchains.

How it is configured varies by ecosystem. In the .NET family, C# language version is declared in project files with values such as "7.3", "8.0", "9.0", or "latest," guiding which syntax and features are accepted. In Kotlin, the compiler option languageVersion can be set to values like "1.6" or "1.7." In some Java ecosystems, source and target compatibility fulfill a related role, though those projects may not label it as a language version. Other languages use similar mechanisms to request a specific edition of the language standard.

Impact and trade-offs are central to languageversion choices. Enabling a newer language version can unlock new syntax and features but may require newer tooling, libraries, and runtime support, and can break older code. Conversely, pinning to an older version improves compatibility with existing environments but forgoes newer capabilities and performance improvements.

Best practices include explicitly pinning a language version in each project, testing thoroughly when upgrading, and consulting language-specific migration guides. Clear documentation of the chosen version helps teams reason about feature availability, compatibility, and forward progress.