codeql/change-notes/1.21/analysis-cpp.md

Improvements to C/C++ analysis

General improvements

New queries

Query	Tags	Purpose
()-declared function called with too few arguments (cpp/too-few-arguments)	Correctness	Find all cases where the number of arguments is less than the number of parameters of the function, provided the function is also properly declared/defined elsewhere.
()-declared function called with mismatched arguments (cpp/mismatched-function-arguments)	Correctness	Find all cases where the types of arguments do not match the types of parameters of the function, provided the function is also properly declared/defined elsewhere.

Changes to existing queries

Query	Expected impact	Change
Mismatching new/free or malloc/delete (cpp/new-free-mismatch)	Fewer false positive results	Fixed an issue where functions were being identified as allocation functions inappropriately. Also affects cpp/new-array-delete-mismatch and cpp/new-delete-array-mismatch.
Overflow in uncontrolled allocation size (cpp/uncontrolled-allocation-size)	More correct results	This query has been reworked so that it can find a wider variety of results.
Memory may not be freed (cpp/memory-may-not-be-freed)	More correct results	Support added for more Microsoft-specific allocation functions, including LocalAlloc, GlobalAlloc, HeapAlloc and CoTaskMemAlloc.
Memory is never freed (cpp/memory-never-freed)	More correct results	Support added for more Microsoft-specific allocation functions, including LocalAlloc, GlobalAlloc, HeapAlloc and CoTaskMemAlloc.
Resource not released in destructor (cpp/resource-not-released-in-destructor)	Fewer false positive results	Resource allocation and deallocation functions are now determined more accurately.
Comparison result is always the same	Fewer false positive results	The range analysis library is now more conservative about floating point values being possibly NaN
Wrong type of arguments to formatting function (cpp/wrong-type-format-argument)	More correct results and fewer false positive results	This query now more accurately identifies wide and non-wide string/character format arguments on different platforms. Platform detection has also been made more accurate for the purposes of this query.
()-declared function called with too many arguments (cpp/futile-params)	Improved coverage	Query has been generalized to find all cases where the number of arguments exceedes the number of parameters of the function, provided the function is also properly declared/defined elsewhere.

Changes to QL libraries