Evils of typedefs and legacy code

Our legacy C++ codebase once was a C codebase. Way back then, there was no standard boolean type. So in the wisdom of the day a type was declared

typedef int tBool;

The major problem with tBool’s is that over time enums, #define or magic constants get assigned to them, or they can be compared to said enums, #defines or magic constants, as they are all int’s.

Which works, but years later *somebody* came along and replaced the tBool for bool, and we started getting issues.

Now as in a lot of large codebases there tends to be a large amount of ignored warnings, and not enough daylight hours to remove them all.

So given that, and that your using Visual Studio 2005, here are the ones you should find and remove.

#define NON_BOOL_DEFINE 42
bool boolValue;

boolValue = NON_BOOL_DEFINE;


Warning C4305: '=' : truncation from 'int' to 'bool'


if( boolValue == NON_BOOL_DEFINE )


Warning C4806: '==' : unsafe operation: no value of type 'bool' promoted to type 'int' can equal the given constant

Another hint your boolean types are being used wrong is this warning

Warning C4800: 'const int' : forcing value to bool 'true' or 'false' (performance warning)