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Compiler plugins


This directory contains code for compiler plugins. These are used to perform additional actions during compilation (such as additional warnings) and also to perform mass code refactoring.

Currently only the Clang compiler is supported


Compiler plugins are enabled automatically by --enable-dbgutil if Clang headers are found or explicitly using --enable-compiler-plugins.


There are two kinds of plugin actions:

Each source has a comment saying whether it’s compile check or a rewriter and description of functionality.

Compile Checks

Used during normal compilation to perform additional checks. All warnings and errors are marked ‘[loplugin]’ in the message.


Rewriters analyse and possibly modify given source files. Usage: make COMPILER_PLUGIN_TOOL=<rewriter_name> Additional optional make arguments:

Modifications will be written directly to the source files.

Some rewriter plugins are dual-mode and can also be used in a non-rewriting mode in which they emit warnings for problematic code that they would otherwise automatically rewrite. When any rewriter is enabled explicitly via make COMPILER_PLUGIN_TOOL=<rewriter_name> it works in rewriting mode (and all other plugins are disabled), but when no rewriter is explicitly enabled (i.e., just make), all dual-mode rewriters are enabled in non-rewriting mode (along with all non-rewriter plugins; and all non–dual-mode plugins are disabled). The typical process to use such a dual-mode rewriter X in rewriting mode is


which first generates a full build without failing due to warnings from plugin X in non-rewriting mode (in case of --enable-werror) and then repeats the build in rewriting mode (during which no object files are generate).

Code Documentation / HowTos