Checked-c-convert: function return values converted, but caller assigns it to variable of old type

[AnnaKornfeldSimpson]

If a function return value is converted from * to _Ptr, callers of that function must be aware of that change and either cast the return value back or change the type of the variable to which they are assigning the return value. If that does not happen there will be an incompatible types error.

Example: parson.checked.c:360
The converted function is declared at: parson.checked.c:94
Original code: parson.c:360
Original function declaration: parson.c:94
Error Produced: assigning to <leftside_type> from incompatible type .

To use this test case:

• Clone https://github.com/AnnaKornfeldSimpson/parson
• Check out the snapshotWeUse branch
• make test to build the original code. make testchecked to build with the copies produced by checked-c-convert.
• convert.sh runs checked-c-convert on the original code and outputs to *checked* files. If you re-run it, also edit parson.checked.c to use parson.checked.h. convert.sh may need modifications to run in Windows.
• Compiler errors can be compared with compilerErrors.txt (produced on a Ubuntu system, not sure if it will perfectly match in Windows)

[dtarditi]

The convert tool has been mostly rewritten (see PR #642). Please reopen this issue if it still exists.