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Merge pull request #589 from jbj/1.19-change-notes

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C++: add missing 1.19 change notes
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Geoffrey White
2018-12-03 15:56:18 +00:00
committed by GitHub
parent 76b1bbc56a 8f60c09804
commit 436ee553a6
2 changed files with 14 additions and 3 deletions
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12
change-notes/1.19/analysis-cpp.md
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@@ -23,8 +23,12 @@
| Expression has no effect | Fewer false positive results | Expressions in template instantiations are now excluded from this query. |
| Global could be static | Fewer false positive results | Variables with declarations in header files are now excluded from this query. |
| Resource not released in destructor | Fewer false positive results | Placement new is now excluded from the query. Also fixed an issue where false positives could occur if the destructor body was not in the snapshot. |
| Memory is never freed | Fewer false positive results | This query now accounts for C++ _placement new_, which returns a pointer that does not need to be freed. |
| Missing return statement (`cpp/missing-return`) | Visible by default | The precision of this query has been increased from 'medium' to 'high', which makes it visible by default in LGTM. It was 'medium' in release 1.17 and 1.18 because it had false positives due to an extractor bug that was fixed in 1.18. |
| Missing return statement | Fewer false positive results | The query is now produces correct results when a function returns a template-dependent type, or makes a non-returning call to another function. |
| Multiplication result converted to larger type (`cpp/integer-multiplication-cast-to-long`) | Fewer false positive results | Char-typed numbers are no longer considered to be potentially large. |
| Non-virtual destructor in base class (`cpp/virtual-destructor`) | Fewer false positive results | This query was copied from file `AV Rule 78.ql` to `NonVirtualDestructorInBaseClass.ql` and renamed from "No virtual destructor" to "Non-virtual destructor in base class". The new version ignores base classes with non-public destructors since we consider those to be adequately protected. The new version retains the query id `cpp/virtual-destructor` and is displayed by default on LGTM, while `AV Rule 78.ql` is not run on LGTM. |
| Overloaded assignment does not return 'this' (`cpp/assignment-does-not-return-this`) | Fewer false positive results | This query now ignores any return statements that are unreachable. |
| Static array access may cause overflow | More correct results | Data flow to the size argument of a buffer operation is now checked in this query. |
| Call to memory access function may overflow buffer | More correct results | Array indexing with a negative index is now detected by this query. |
| Self comparison | Fewer false positive results | Code inside macro invocations is now excluded from the query. |
@@ -39,6 +43,8 @@
## Changes to QL libraries
* Added a hash consing library for structural comparison of expressions.
* `getBufferSize` now detects variable size structs more reliably.
* Buffer.qll now treats arrays of zero size as a special case.
* Added a hash consing library (`semmle.code.cpp.valuenumbering.HashCons`) for structural comparison of expressions. Unlike the existing library for global value numbering, this library implements a pure syntactic comparison of expressions and will equate expressions even if they may not compute the same value.
* The `Buffer.qll` library has more conservative treatment of arrays embedded in structs. This reduces false positives in a number of security queries, especially `cpp/overflow-buffer`.
* Pre-C99 encodings of _flexible array members_ are recognized more reliably.
* Arrays of zero size are now treated as a special case.
* The library `semmle.code.cpp.dataflow.RecursionPrevention` is now deprecated. It was an aid for transitioning data-flow queries from 1.16 to 1.17, and it no longer has any function. Imports of this library should simply be deleted.

5
cpp/ql/src/semmle/code/cpp/dataflow/RecursionPrevention.qll
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@@ -1,4 +1,9 @@
/**
* DEPRECATED: Recursion through `DataFlow::Configuration` is impossible in
* Semmle Core 1.17 and above. There is no need for this module because it's
* impossible to accidentally depend on recursion through
* `DataFlow::Configuration` in current releases.
*
* When this module is imported, recursive use of `DataFlow::Configuration` is
* disallowed. Importing this module will guarantee the absence of such
* recursion, which is unsupported and will be unconditionally disallowed in a