[analyzer][NFC] Remove useless class BuiltinBug

...because it provides no useful functionality compared to its base
class `BugType`.

A long time ago there were substantial differences between `BugType` and
`BuiltinBug`, but they were eliminated by commit 1bd58233 in 2009 (!).
Since then the only functionality provided by `BuiltinBug` was that it
specified `categories::LogicError` as the bug category and it stored an
extra data member `desc`.

This commit sets `categories::LogicError` as the default value of the
third argument (bug category) in the constructors of BugType and
replaces use of the `desc` field with simpler logic.

Note that `BugType` has a data member `Description` and a non-virtual
method `BugType::getDescription()` which queries it; these are distinct
from the member `desc` of `BuiltinBug` and the identically named method
`BuiltinBug::getDescription()` which queries it. This confusing name
collision was a major motivation for the elimination of `BuiltinBug`.

As this commit touches many files, I avoided functional changes and left
behind FIXME notes to mark minor issues that should be fixed later.

Differential Revision: https://reviews.llvm.org/D158855

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/unittests/StaticAnalyzer/CallEventTest.cpp b/clang/unittests/StaticAnalyzer/CallEventTest.cpp
index b1ae591eaf7e..5be25d2ada67 100644
--- a/clang/unittests/StaticAnalyzer/CallEventTest.cpp
+++ b/clang/unittests/StaticAnalyzer/CallEventTest.cpp
@@ -36,11 +36,11 @@ void reportBug(const CheckerBase *Checker, const CallEvent &Call,
 }
 
 class CXXDeallocatorChecker : public Checker<check::PreCall> {
-  std::unique_ptr<BuiltinBug> BT_uninitField;
+  std::unique_ptr<BugType> BT_uninitField;
 
 public:
   CXXDeallocatorChecker()
-      : BT_uninitField(new BuiltinBug(this, "CXXDeallocator")) {}
+      : BT_uninitField(new BugType(this, "CXXDeallocator")) {}
 
   void checkPreCall(const CallEvent &Call, CheckerContext &C) const {
     const auto *DC = dyn_cast<CXXDeallocatorCall>(&Call);