Refers to the information that can be inferred or known at the time source code is compiled, as opposed to information that can only be inferred when source code is run. Do not use this tag for questions about the time it takes for source code to be compiled.
In computer-science, compile time refers to either the operations performed by a compiler (the "compile-time operations"), programming-language requirements that must be met by source code for it to be successfully compiled (the "compile-time requirements"), or properties of the program that can be reasoned about at compile time.
The operations performed at compile time usually include syntax-analysis, various kinds of semantic-analysis (e.g., type checks and instantiation of template) and code-generation.
Programming language definitions usually specify compile time requirements that source-code must meet to be successfully compiled. For example, that the amount of storage required by types and variable can be deduced.
Properties of a program that can be reasoned about at compile time include range-checks (e.g., proving that an array index will not exceed the array bound), deadlock freedom in concurrent languages, or timings (e.g., proving that a sequence of code takes no more than an allocated amount of time).
Compile time occurs before link-time (when the output of one or more compiled files are joined together) and runtime (when a program is executed).
In some programming languages it may be necessary for some compilation and linking to occur at runtime.
There is a trade-off between compile-time and link-time in that many compile time operations can be deferred to link-time without incurring extra run-time.
"Compile time" can also refer to the amount of time required for compilation.
Source: Wikipedia
