[Codegenerator] Invalid Condition

[ebehner]

What happened?

Currently, when decompiling function main of fmt.zip the decompilation process crashes due to an invalid condition.

More precisely, the reaching condition of an AST node is evaluated as false because the type of a constant is wrong. (The problem with type propagation is tracked in Issue #42.)
Nevertheless, the program should not crash. The program occurs because the function _condition_string does not assume that a condition is true or false.

Proposal
There are multiple options for this problem.

1. In general, if a condition is false, then we can simply remove the true branch and execute always the false branch, i.e., we can substitute the condition node with the false branch. Symmetrically, one would replace each condition node with condition true by its true branch. But, in cases like this where the condition should not be false, we may lose content we do not want to lose.
2. We simply have a condition that is false or true and add this scenario to the function _condition_string.

In both cases, a warning could be nice.

How to reproduce?

Try to decompile main in fmt.zip

Affected Binary Ninja Version(s)

2.4.2846

[ebehner]

Proposal 2 and a new Issue that also implements 1 with config option.

[steffenenders]

/cib

[github-actions]

Branch issue-59-_Codegenerator_Invalid_Condition created!