Build system tricks

Ignore a change

Suppose you add a new function to a header file that many other files depend on. Most files that include it do not need to be recompiled. Solution:

• Make the changes in the header file

• Compile the files that depend on the new function

• Do a full build with --assume-old-touch $header.

Find dependencies

The assume new and dry run flags in combination show you what would rebuild if you were to modify that file.