[cfe-dev] Type conversion problem in Clang Static Analyzer

[Artem Dergachev via cfe-dev]

Hello,

There are, roughly speaking, three kinds of SVal's:
- "concrete" values, such as "32-bit 1" or the whole structure of known 
values, such as "{1, 2}",
- "symbols" (with which the analyzer denotes values it cannot instantly 
reason about for future reference - they are stored inside 
nonloc::SymbolVal-class SVal's),
- "regions" (segments of memory - they are usually stored inside 
loc::MemRegionVal).

There are also special values, like "Unknown" or "Undefined". You can 
see the doxygen for the SVal class for more info on its sub-classes.

The getAsSymbol() methods are for obtaining symbols whenever the value 
actually is a symbol or something closely related to it (eg. 
SymbolicRegion is a region pointed to by a pointer-type symbol, so it 
works for those as well).

These methods return nullptr if there's no symbol inside the value. So 
you can think of it as some kind of advanced dynamic_cast - it returns a 
symbol if there's a symbol, and NULL if there's no symbol to return.

What you need to do next depends on why did you want specifically a 
symbol, rather than a generic SVal.