From e90403be31b4c6ddd19e655c0c8086ec14a89dae Mon Sep 17 00:00:00 2001 From: Dave Bartolomeo Date: Wed, 29 May 2019 17:46:24 -0700 Subject: [PATCH 1/2] C++: Make `constructor-used-as-copy-constructor` warning/low This query is supposed to look for constructors that unintentionally qualify as copy constructors due to default arguments. There are quite a few real-world projects that define such constructors intentionally. I've reduced the severity to "warning" and the precision to "low" due to the high false positive rate. --- cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.qhelp | 3 +-- cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.ql | 4 ++-- 2 files changed, 3 insertions(+), 4 deletions(-) diff --git a/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.qhelp b/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.qhelp index f76c96d36d08..1da61ff04ce9 100644 --- a/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.qhelp +++ b/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.qhelp @@ -11,8 +11,7 @@ when their default arguments are taken into account. An example would be a const of the form X(const X& rhs, int i = 0). A compiler will use such a constructor as a copy constructor in preference to the default member-wise copy constructor that it would otherwise generate. Since this is usually not what was intended, constructors of the form often do not provide the right -semantics for copying objects of the class, making them potentially dangerous. Even when this sort of -thing has been done intentionally, it is confusing and in bad taste, and should be avoided. +semantics for copying objects of the class, making them potentially dangerous.

diff --git a/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.ql b/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.ql index 0b847e795c64..458616eea8c5 100644 --- a/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.ql +++ b/cpp/ql/src/jsf/4.10 Classes/AV Rule 77.1.ql @@ -2,8 +2,8 @@ * @name Constructor with default arguments will be used as a copy constructor * @description Constructors with default arguments should not be signature-compatible with a copy constructor when their default arguments are taken into account. * @kind problem - * @problem.severity error - * @precision high + * @problem.severity warning + * @precision low * @id cpp/constructor-used-as-copy-constructor * @tags reliability * readability From f4d41a15d798eae843e6f448175bcf49a6049609 Mon Sep 17 00:00:00 2001 From: Dave Bartolomeo Date: Thu, 30 May 2019 08:31:15 -0700 Subject: [PATCH 2/2] C++: Add change not --- change-notes/1.21/analysis-cpp.md | 1 + 1 file changed, 1 insertion(+) diff --git a/change-notes/1.21/analysis-cpp.md b/change-notes/1.21/analysis-cpp.md index 00e7e98c5f9c..24ae518ca28b 100644 --- a/change-notes/1.21/analysis-cpp.md +++ b/change-notes/1.21/analysis-cpp.md @@ -30,6 +30,7 @@ | Wrong type of arguments to formatting function (`cpp/wrong-type-format-argument`) | Fewer false positive results | Non-standard uses of %L are now understood. | | `()`-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. | | Use of potentially dangerous function (`cpp/potentially-dangerous-function`) | Fewer results | Results relating to the standard library `gets` function have been moved into a new query (`dangerous-function-overflow`). | +| Constructor with default arguments will be used as a copy constructor (`cpp/constructor-used-as-copy-constructor`) | Lowered severity and precision | The severity and precision of this query have been reduced to "warning" and "low", respectively, due to this coding pattern being used intentionally and safely in a number of real-world projects. | ## Changes to QL libraries - The predicate `Declaration.hasGlobalName` now only holds for declarations that are not nested in a class. For example, it no longer holds for a member function `MyClass::myFunction` or a constructor `MyClass::MyClass`, whereas previously it would classify those two declarations as global names.