Commit my clang plugin and fix up documentation.

tools/clang/plugins/README.chromium

Index: tools/clang/plugins/README.chromium
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+Clang plugins: How to use and how to write

[Nico, 2011/02/02 23:13:06]

I'd prefer this to be on the wiki page, and this README just to link to there.

(If you want, I can move it over later.)

+------------------------------------------
+
+I) Compiling
+------------
+
+TODO(thakis): Explain how to compile these, since I'm not copying the clang
+build system here.
+
+II) Using these plugins as part of your build process
+-----------------------------------------------------
+
+Nico has awesomely added support to clang to run plugins, and gyp support to
+run them as part of the normal build process. There are now two gyp variables
+you can set to run a plugin:
+
+  clang_load: loads a specific shared object plugin
+  clang_add_plugin: tells clang to run a specific PluginASTAction
+
+So for example, you could use the plugin in this directory with:
+
+  GYP_DEFINES='clang=1 clang_load=/path/to/libFindBadConstructs.so clang_add_plugin=find-bad-constructs'
+
+III) Writing plugins
+--------------------
+
+As a utility to other plugin authors, I've written the ChromeClassTester class
+that you can derive from, which will call CheckChromeClass() on every
+class/struct encountered in a chrome header while filtering out blacklisted
+classes, namespaces and directories.

[Nico, 2011/02/02 23:13:06]

This should have a paragraph on "You usually don't want to write a plugin, only
do this as a last resort because clang's api here is not stable and does break
often in practice, if you write a plugin you're committed to maintaining it, all
error messages you might add should clearly call out they're originating from
your plugin, diagnostics that are useful in general should be upstreamed to
clang instead, if you want to do something else than to add errors, consider
using clang's c api instead yadda yadda yadda"