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

Improvements to C/C++ analysis

General improvements

New queries

Query	Tags	Purpose

Changes to existing queries

Query	Expected impact	Change
Commented-out code (cpp/commented-out-code)	More correct results	Commented out preprocessor code is now detected by this query.
Dead code due to goto or break statement (cpp/dead-code-goto)	Fewer false positive results	Functions containing preprocessor logic are now excluded from this analysis.
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
Use of potentially dangerous function	More correct results	Calls to localtime, ctime and asctime are now detected by this query.
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.
Wrong type of arguments to formatting function (cpp/wrong-type-format-argument)	Fewer false positive results	Non-standard uses of %L are now understood.

Changes to QL libraries