Compiler and method for avoiding unnecessary recompilation

A system for minimizing rebuilding of a program for execution on a computer, comprising:

• a compiler operative to compile a source code file and any header files included by the source code file into an object code file, and to analyze at least one type of dependency of the object code file being compiled on classes declared in said header files to yield any class dependencies of the object code file on the classes;
• a change detector for detecting at least one type of change made to the classes to yield any class changes;
• a minimal rebuild engine in communication with the compiler and the change detector for receiving the class dependencies from the compiler and the class changes from the change detector, the minimal rebuild engine being operative to compare the class dependencies and the class changes to determine whether the class dependencies of the object code file intersect the class changes;
• and
• a compiler driver in communication with the compiler and the minimal rebuild engine and operative to cause the compiler to compile a plurality of source code files for first building the program, and further operative to cause recompiling by the compiler of a subset of the source code files for rebuilding the program, wherein the subset of the source code files excludes the source code files that are unchanged since first building the program and that were compiled into object code files whose class dependencies do not intersect the class changes.

In a compiler, a method of minimizing rebuilding of an executable program, comprising the steps of:

• storing information indicative of any dependencies of an object module on any of a plurality of classes declared in any header files used in last compiling the object module;
• detecting any changes made since last compiling the object module to said any header files and to any source files that were used in last compiling the object module;
• and
• recompiling the object module except at least where said detected changes are solely to parts of said classes which are not indicated by the stored information as dependencies of the object module.