llvm-project/clang
Jordan Rose 801916baf1 [analyzer] Suppress paths involving a reference whose rvalue is null.
Most map types have an operator[] that inserts a new element if the key
isn't found, then returns a reference to the value slot so that you can
assign into it. However, if the value type is a pointer, it will be
initialized to null. This is usually no problem.

However, if the user /knows/ the map contains a value for a particular key,
they may just use it immediately:

   // From ClangSACheckersEmitter.cpp
   recordGroupMap[group]->Checkers

In this case the analyzer reports a null dereference on the path where the
key is not in the map, even though the user knows that path is impossible
here. They could silence the warning by adding an assertion, but that means
splitting up the expression and introducing a local variable. (Note that
the analyzer has no way of knowing that recordGroupMap[group] will return
the same reference if called twice in a row!)

We already have logic that says a null dereference has a high chance of
being a false positive if the null came from an inlined function. This
patch simply extends that to references whose rvalues are null as well,
silencing several false positives in LLVM.

<rdar://problem/13239854>

llvm-svn: 176371
2013-03-01 19:45:10 +00:00
..
INPUTS
bindings
docs Attempt to not place ownership qualifiers on the result type 2013-03-01 07:58:16 +00:00
examples
include Attempt to not place ownership qualifiers on the result type 2013-03-01 07:58:16 +00:00
lib [analyzer] Suppress paths involving a reference whose rvalue is null. 2013-03-01 19:45:10 +00:00
runtime
test [analyzer] Suppress paths involving a reference whose rvalue is null. 2013-03-01 19:45:10 +00:00
tools
unittests Remove whitespace at end of file. 2013-03-01 18:11:39 +00:00
utils
www [analyzer] Reword FAQ 2013-03-01 06:38:16 +00:00
.arcconfig
.gitignore
CMakeLists.txt
CODE_OWNERS.TXT
INSTALL.txt
LICENSE.TXT
Makefile
ModuleInfo.txt
NOTES.txt
README.txt

README.txt

//===----------------------------------------------------------------------===//
// C Language Family Front-end
//===----------------------------------------------------------------------===//

Welcome to Clang.  This is a compiler front-end for the C family of languages
(C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM
compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things
beyond just compiling code: we intend for Clang to be host to a number of
different source level tools.  One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read
the relevant web sites.  Here are some pointers:

Information on Clang:              http://clang.llvm.org/
Building and using Clang:          http://clang.llvm.org/get_started.html
Clang Static Analyzer:             http://clang-analyzer.llvm.org/
Information on the LLVM project:   http://llvm.org/

If you have questions or comments about Clang, a great place to discuss them is
on the Clang development mailing list:
  http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev

If you find a bug in Clang, please file it in the LLVM bug tracker:
  http://llvm.org/bugs/