[analyzer] Add 12.0.0. release notes

[Szelethus]

Summary

Seems like we're a bit late again, but not too late! I've been absent for a large portion of the 12.0.0's development, so please feel free to point out if I missed anything. Same thing with contributors I forgot to add as a reviewer.

We have a bad track record of finishing, but forgetting to enable GSoC projects -- did the same happen to SmartPtrChecker or that still needs refinement?

[tstellar]

You can push this directly to the release/12.x branch when it's ready.

[NoQ]

Thanks!!

We have a bad track record of finishing, but forgetting to enable GSoC projects -- did the same happen to SmartPtrChecker or that still needs refinement?

Still needs refinement. One large missing piece is that inlined defensive check suppressions weren't generalized for smart pointers.

clang/docs/ReleaseNotes.rst

329

I suggest expanding a bit: "... is a WebKit coding convention checker that flags raw pointers to reference-counted objects captured by lambdas and suggests using intrusive reference-counting smart pointers instead." Something similar for the next item.

[Szelethus]

Fix'd!

[steakhal]

I'm ok with this on my part.

[Szelethus]

ping

[isthismyaccount]

LGTM on my part.

[Szelethus]

Pushed this to the 12.0.0 release branch, just forgot to close it!

clang/docs/ReleaseNotes.rst

 libclang
 --------
 
 - ...
 
 Static Analyzer
 ---------------
 
-- ...
+.. 3ff220de9009 [analyzer][StdLibraryFunctionsChecker] Add POSIX networking functions
+.. ...And a million other patches.
+- Improve the analyzer's understanding of several POSIX functions.
+
+.. https://reviews.llvm.org/D86533#2238207
+- Greatly improved the analyzer’s constraint solver by better understanding
+  when constraints are imposed on multiple symbolic values that are known to be
+  equal or known to be non-equal. It will now also efficiently reject impossible
+  if-branches between known comparison expressions. (Incorrectly stated as a
+  11.0.0 feature in the previous release notes)
+
+.. 820e8d8656ec [Analyzer][WebKit] UncountedLambdaCaptureChecker
+- New checker: :ref:`webkit.UncountedLambdaCapturesChecker<webkit-UncountedLambdaCapturesChecker>`
+  is a WebKit coding convention checker that flags raw pointers to
+  reference-counted objects captured by lambdas and suggests using intrusive
+  reference-counting smart pointers instead.
+
+.. 8a64689e264c [Analyzer][WebKit] UncountedLocalVarsChecker
+- New checker: :ref:`alpha.webkit.UncountedLocalVarsChecker<alpha-webkit-UncountedLocalVarsChecker>`
+  is a WebKit coding convention checker that intends to make sure that any
+  uncounted local variable is backed by a ref-counted object with lifetime that
+  is strictly larger than the scope of the uncounted local variable.
+
+.. i914f6c4ff8a4 [StaticAnalyzer] Support struct annotations in FuchsiaHandleChecker
+- ``fuchia.HandleChecker`` now recognizes handles in structs; All the handles
+  referenced by the structure (direct value or ptr) would be treated as
+  containing the release/use/acquire annotations directly.
+
+.. 8deaec122ec6 [analyzer] Update Fuchsia checker to catch releasing unowned handles.
+- Fuchsia checkers can detect the release of an unowned handle.
+
+- Numerous fixes and improvements to bug report generation.
 
 .. _release-notes-ubsan:
 
 Undefined Behavior Sanitizer (UBSan)
 ------------------------------------
 
 Core Analysis Improvements
 ==========================

clang/docs/analyzer/checkers.rst

 We also define a set of safe transformations which if passed a safe value as an input provide (usually it's the return value) a safe value (or an object that provides safe values). This is also a heuristic.
 
 - constructors of ref-counted types (including factory methods)
 - getters of ref-counted types
 - member overloaded operators
 - casts
 - unary operators like ``&`` or ``*``
 
+.. _alpha-webkit-UncountedLocalVarsChecker:
+
 alpha.webkit.UncountedLocalVarsChecker
 """"""""""""""""""""""""""""""""""""""
 The goal of this rule is to make sure that any uncounted local variable is backed by a ref-counted object with lifetime that is strictly larger than the scope of the uncounted local variable. To be on the safe side we require the scope of an uncounted variable to be embedded in the scope of ref-counted object that backs it.
 
 These are examples of cases that we consider safe:
 
   .. code-block:: cpp