Without the last commit, this addition to the test gives the following
results:
```
+| AV Rule 82.cpp:176:14:176:22 | operator= | Assignment operator in class Forgivable does not return a reference to *this. |
+| AV Rule 82.cpp:181:14:181:22 | operator= | Assignment operator in class Forgivable does not return a reference to *this. |
```
I removed this condition in #362, thinking it was covered by the new
conditions on return statements, but it turns out it wasn't in at least
the following cases.
1. Assignment operators that are deleted or marked private in order to
make them inaccessible.
2. Templates whose body was not extracted.
While some of these results are technically valid, they are not nearly
as interesting as the results that this query was designed to produce.
AV Rule 78 has proved too noisy for use on lgtm.com. However, if we make the rule less noisy by, say, allowing a protected destructor to be non-virtual, we're no longer actually enforcing AV Rule 78. Instead, I've copied AV Rule 78 into NonVirtualDestructorInBaseClass.ql, given the new query the `@id` that AV Rule 78 had, and given AV Rule 78 a new JSF-specific `@id`. The new rule allows non-public non-virtual destructors, which is the problem originally reported by an lgtm.com user.
The previous formulation of this predicate caused a CP in snapshots
where a variable had a large number of definitions and also reached a
large number of sub-basic-blocks.
This should fix performance of https://github.com/FrodeSolheim/fs-uae
and https://github.com/libretro/libretro-uae.
The `FlowVar.getAnAccess` predicate is still at risk of CP'ing when a
large group of defs has a large group of uses, but that has not been
observed to happen in practice yet. We would need to make
`localFlowStep` expose phi definitions in order to avoid that risk.
@rdmarsh2 has been working on various queries and libraries on top of the IR, and has pointed out that having to always refer to an operand of an instruction by the pair of (instruction, operandTag) makes using the IR a bit clunky. This PR adds a new `Operand` IPA type that represents an operand of an instruction. `OperandTag` still exists, but is now an internal type used only in the IR implementation.
