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Stephan Bergmann 75f0f9d553 New loplugin:faileddyncast

Offline discussion about tdf#96067 "Crash on undo row inserts" brought up the
idea to warn about cases where uses of dynamic_cast are statically knwon to
always fail.  Clang's clang::AST::CXXDynamicCastExpr::isAlwaysNull already
implements such a check, reporting true if the casted-from class is final, but
has two issues:

For one, it does not work for template code, when one of the involved types is a
template parameter type (so e.g., DestType->castAs<PointerType>() can crash).

For another, it misses the opportunity to report true if the casted-to type is
final and only derives from the casted-from type non-publicly.  My hope was that
this, after the "final" decorations in 548c43238d
"Mark some classes as final," might turn up the culprit of tdf#96067 (with a
scenario similar to the failed dynamic_cast on private derivation in
63b67ab5ca "Use public derivation, and remove
then-unnecessary downcasts")---but not so.

Change-Id: I962ee19820758f9c601f4a292da7f37fa9dff5ce

2016-01-12 15:00:33 +01:00

clang

New loplugin:faileddyncast

2016-01-12 15:00:33 +01:00

.gitignore

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Makefile

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Makefile-clang.mk

gbuild/config stop using VERBOSE, use only verbose=t

2015-08-11 04:34:45 +00:00

Makefile.mk

Generalize COM_GCC_IS_CLANG -> COM_IS_CLANG

2015-11-12 17:37:11 +00:00

README

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README

Compiler plugins.


== Overview ==

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 (http://wiki.documentfoundation.org/Development/Clang).


== Usage ==

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


== Functionality ==

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 ===

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


=== Rewriters ===

Rewriters analyse and possibly modify given source files.
Usage: make COMPILER_PLUGIN_TOOL=<rewriter_name>
Additional optional make arguments:
- it is possible to also pass FORCE_COMPILE_ALL=1 to make to trigger rebuild of all source files,
    even those that are up to date.
- UPDATE_FILES=<scope> - limits which modified files will be actually written back with the changes
    - mainfile - only the main .cxx file will be modified (default)
    - all - all source files involved will be modified (possibly even header files from other LO modules),
        3rd party header files are however never modified
    - <module> - only files in the given LO module (toplevel directory) will be modified (including headers)

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

  make COMPILER_PLUGIN_WARNINGS_ONLY=X \
  && make COMPILER_PLUGIN_TOOL=X FORCE_COMPILE_ALL=1 UPDATE_FILES=all

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 ==

http://wiki.documentfoundation.org/Clang_plugins