Previously we thought it possible to get from top to bottom of a block like "switch { case f(): ... }", when in fact this is only possible if there are no case blocks to execute.
I also add tests for two possible corner cases of a switch without a test-expression: a completely empty switch (the 'true' is indeed the last node) and switch with an empty default block (a single 'skip' is generated for the default block and the 'true' is not the last node)
https://github.com/github/codeql-go/pull/184 added a regression test for the non-termination it was fixing. The fix hasn't made it into Code Scanning yet, so for the time being it will fail with precisely that non-termination when analysing the regression tests.
The call target must belong to the method set of a type that implements the interface type of the method call receiver, if any.
For example, assume `h` has type `hash.Hash`, then `h.Write(...)` should only be resolved to implementations of `Write` in types implementing `hash.Hash`, not arbitrary other `Writer`s.
* Centralise use of raw types and database predicates in FieldParent and FieldBase classes
* Deduplicate type predicates common to all fields
* Deduplicate predicates common to function parameters and results
This both checks that many common control-flow structures print as expected, and checks our unique child node numbering, which would otherwise give the same label to a file's package (its 0th child expression) and its 0th declaration.
This gives those classes satisfied by an AstNode that are considered useful for developer understanding, cf. getAQlClass which returns all satisfied classes and hides overridden ones, even if they are interesting.
Known shortcomings:
* Uses getAQlClass rather than tagging AST nodes with a canonical class, as the C++ version of the same query does
* Types and go.mod lines are not printed informatively (typically we just get a short description of the node kind, e.g. 'function type')
* Children are always named for their child indices; we should give informative names to the edges where an accessor is declared (e.g. IfStmt names its children 'init', 'cond', 'if', 'else')
