Fix buffer underrun (invalid read) triggered during diagnostic rendering.  The test would overflow when computing '0 - 1'.

I don't have a good testcase for this that does not depend on system headers.
It did not trigger with preprocessed output, and I had trouble reducing the example.

Fixes <rdar://problem/13324594>.

Thanks to Michael Greiner for reporting this issue.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177201 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Address Jordan’s review of r177138 (a micro optimization)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177204 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] BugReporterVisitors: handle the case where a ternary operator is wrapped in a cast.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177205 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Use isLiveRegion to determine when SymbolRegionValue is dead.

Fixes a FIXME, improves dead symbol collection, suppresses a false positive,
which resulted from reusing the same symbol twice for simulation of 2 calls to the same function.

Fixing this lead to 2 possible false negatives in CString checker. Since the checker is still alpha and
the solution will not require revert of this commit, move the tests to a FIXME section.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177206 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Address a TODO in the StreamChecker; otherwise the output is non-deterministic.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177207 91177308-0d34-0410-b5e6-96231b3b80d8
Improve template diffing handling of default integer values.

When the template argument is both default and value dependent, the expression
retrieved for the default argument cannot be evaluated, thus never matching
any argument value.  To get the proper value, get the template argument
from the desugared template specialization.  Also, output the original
expression to provide more information about the argument mismatch.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177209 91177308-0d34-0410-b5e6-96231b3b80d8