Incremental build systems are essential for fast, reproducible software builds. Incremental build systems enable short feedback cycles when they capture dependencies precisely and selectively execute build tasks efficiently. A much overlooked feature of build systems is the expressiveness of the scripting language, which directly influences the maintainability of build scripts. In this paper, we present a new incremental build algorithm that allows build engineers to use a full-fledged programming language with explicit task invocation, value and file inspection facilities, and conditional and iterative language constructs. In contrast to prior work on incrementality for such programmable builds, our algorithm scales with the number of tasks affected by a change and is independent of the size of the software project being built. Specifically, our algorithm accepts a set of changed files, transitively detects and re-executes affected build tasks, but also accounts for new task dependencies discovered during building. We have evaluated the performance of our algorithm in a real-world case study and confirm its scalability.

It is common practice to bootstrap compilers of programming languages. By using the compiled language to implement the compiler, compiler developers can code in their own high-level language and gain a large-scale test case. In this paper, we investigate bootstrapping of compiler-compilers as they occur in language workbenches. Language workbenches support the development of compilers through the application of multiple collaborating domain-specific meta-languages for defining a language's syntax, analysis, code generation, and editor support. We analyze the bootstrapping problem of language workbenches in detail, propose a method for sound bootstrapping based on fixpoint compilation, and show how to conduct breaking meta-language changes in a bootstrapped language workbench. We have applied sound bootstrapping to the Spoofax language workbench and report on our experience.