move documentation of plugins to the .cxx files

It's mostly there already anyway, no need to duplicate it.

Change-Id: I5b066f90725a064fb0746e1411900e835e3f66c3

compilerplugins/README

@@ -18,10 +18,12 @@ are found or explicitly using --enable-compiler-plugins.
 
 == Functionality ==
 
-There are two kinds of modules:
+There are two kinds of plugin actions:
 - compile checks - these are run during normal compilation
 - rewriters - these must be run manually and modify source files
 
+Each source has a comment saying whether it's compile check or a rewriter
+and description of functionality.
 
 === Compile checks ===
 
@@ -29,42 +31,13 @@ Used during normal compilation to perform additional checks.
 All warnings and errors are marked '[loplugin]' in the message.
 
 
-==== Unused variable check ====
-
-- unused parameter 'foo' [loplugin]
-- unused variable 'foo' [loplugin]
-
-Additional check for unused variables.
-
-
-==== Body of if/while/for not in {} ====
-
-- statement aligned as second statement in if/while/for body but not in a statement block [loplugin]
-
-Warn about the following construct:
-
-    if( a != 0 )
-        b = 2;
-        c = 3;
-        
-Here either both statements should be inside {} or the second statement in indented wrong.
-
-
-==== Sal log areas ====
-
-- unknown log area 'foo' (check or extend sal/inc/sal/log-areas.dox) [loplugin]
-
-Check area used in SAL_INFO/SAL_WARN macros against the list in sal/inc/sal/log-areas.dox and
-report if the area is not listed there. The fix is either use a proper area or add it to the list
-if appropriate.
-
-
 === Rewriters ===
 
 Rewriters analyse and possibly modify given source files.
 Usage: make COMPILER_PLUGIN_TOOL=<rewriter_name>
 Modifications will be written directly to the source files.
 
+
 == Code documentation / howtos ==
 
 TBD

compilerplugins/clang/bodynotinblock.cxx

@@ -21,6 +21,14 @@ This is a compile check.
 
 Check for two statements that are both indented to look like a body of if/while/for
 but are not inside a compound statement and thus the second one is unrelated.
+
+For example:
+
+    if( a != 0 )
+        b = 2;
+        c = 3;
+
+Here either both statements should be inside {} or the second statement in indented wrong.
 */
 
 BodyNotInBlock::BodyNotInBlock( ASTContext& context )

compilerplugins/clang/plugin.cxx

@@ -15,6 +15,9 @@
 
 #include "pluginhandler.hxx"
 
+/*
+Base classes for plugin actions.
+*/
 namespace loplugin
 {
 

compilerplugins/clang/pluginhandler.cxx

@@ -16,6 +16,10 @@
 #include <stdio.h>
 #include <unistd.h>
 
+/*
+This source file manages all plugin actions. It is not necessary to modify this
+file when adding new actions.
+*/
 namespace loplugin
 {
 

compilerplugins/clang/postfixincrementfix.cxx

@@ -13,6 +13,12 @@
 #include <clang/AST/ASTContext.h>
 #include <clang/Basic/SourceManager.h>
 
+/*
+This is a rewriter.
+
+Change all postfix ++ operators of non-trivial types to prefix if possible.
+*/
+
 namespace loplugin
 {
 

compilerplugins/clang/sallogareas.cxx

@@ -22,7 +22,9 @@ namespace loplugin
 /*
 This is a compile check.
 
-Check that areas used in SAL_LOG/SAL_WARN are listed in sal/inc/sal/log-areas.dox .
+Check area used in SAL_INFO/SAL_WARN macros against the list in sal/inc/sal/log-areas.dox and
+report if the area is not listed there. The fix is either use a proper area or add it to the list
+if appropriate.
 */
 
 SalLogAreas::SalLogAreas( ASTContext& context )