FS-25 Try 2

[cd1m0]

This PR is based on work done by @norhh here #11. The previous PR did a lot of good work to uncover all of the places we need to fix to handle shadowing. However, the fixes in that PR were complicated by the fact that a lot of the code they touched was not well written (by me) and over-complicated. This got in the way of fixing.

In this PR we attempt to first fix the problems in the code, and then to add code to handle the various cases of name collisions/shadowing. In detail:

1. Cleanup:

   • Convert the InstrumentationContext interface into its own utility class. The InstrumentationContext class is responsible for keeping toghether all state shared between the instrumentation of all invariants

   • Rename UIDGenerator to the better NameGenerator and move it inside of InstrumentationContext (it used to be a global var)

   • Add the existingNames field to NameGenerator to allow it to avoid all names that existed in the original AST

   • Convert several constants from global constant strings into fields of InstrumentationContext. Furthermore the values of these fields were obtained by calling into NameGenerator. This guarantees that they wont overlap with existing names, and all future instrumentation names wont conflict with them. This includes:

     SCRIBBLE_VAR -> InstrumentationContext.structVar
REENTRANCY_UTILS_CONTRACT -> InstrumentationContext.utilsContractName
CHECK_STATE_INVS_FUN -> InstrumentationContext.checkStateInvsFuncName
OUT_OF_CONTRACT -> InstrumentationContext.outOfContractFlagName

   • Introduced the InstrumentationContext.internalInvariantCheckers map and corresponding function getInternalInvariantCheckerName(ContractDefinition) to generate names for the internal contract-invariant checker helper function without collisions.

   • Changed the code in interpose(..) to use NameGenerator when renaming the original functions to avoid collisions

   • Added the TranspilingContext class. It contains the state that is need to compile JUST the annotations for one function/contract. This includes a reference to InstrumentationContext, as well as the typing and semantic information for the group of annotations for the given function/contract.

   • Changed flattenExpr and generateExpressions to take a TranspilingContext instead of the jumble of arguments they had before

   • Changed the flattening and AST generation code to use TranspilingContext when computing field names for let-bindings, internal let-vars, internal old-vars as well as some other internals such as the scratch field (what used to be MSTORE_SCRATCH_FIELD) and the CHECK_INVS_AT_END flag.

   • Added tests (see test/samples/increment_inherited_collision.sol).

[blitz-1306]

Looks good. Just a smaller suggestion.

[blitz-1306]

We can use the object here, ofcourse. But would be cool to have a Map<string, number> instead. It may have some builerplate code, but on large amount of keys it would be more efficient.

[norhh]

Looks good