Implement Rule 28-6-4, require use of std::remove_if and similar functions by MichaelRFairhurst · Pull Request #1046 · github/codeql-coding-standards

MichaelRFairhurst · 2026-02-18T22:56:15Z

Description

Implement Rule 28-6-4

Change request type

Release or process automation (GitHub workflows, internal scripts)
Internal documentation
External documentation
Query files (.ql, .qll, .qls or unit tests)
External scripts (analysis report or other code shipped as part of a release)

Rules with added or modified queries

No rules added
Queries have been added for the following rules:
- RULE-28-6-4
Queries have been modified for the following rules:
- rule number here

Release change checklist

A change note (development_handbook.md#change-notes) is required for any pull request which modifies:

The structure or layout of the release artifacts.
The evaluation performance (memory, execution time) of an existing query.
The results of an existing query in any circumstance.

If you are only adding new rule queries, a change note is not required.

Author: Is a change note required?

Yes
No

🚨🚨🚨
Reviewer: Confirm that format of shared queries (not the .qll file, the
.ql file that imports it) is valid by running them within VS Code.

Confirmed

Reviewer: Confirm that either a change note is not required or the change note is required and has been added.

Confirmed

Query development review checklist

For PRs that add new queries or modify existing queries, the following checklist should be completed by both the author and reviewer:

Author

Have all the relevant rule package description files been checked in?
Have you verified that the metadata properties of each new query is set appropriately?
Do all the unit tests contain both "COMPLIANT" and "NON_COMPLIANT" cases?
Are the alert messages properly formatted and consistent with the style guide?
Have you run the queries on OpenPilot and verified that the performance and results are acceptable?
As a rule of thumb, predicates specific to the query should take no more than 1 minute, and for simple queries be under 10 seconds. If this is not the case, this should be highlighted and agreed in the code review process.
Does the query have an appropriate level of in-query comments/documentation?
Have you considered/identified possible edge cases?
Does the query not reinvent features in the standard library?
Can the query be simplified further (not golfed!)

Reviewer

Have all the relevant rule package description files been checked in?
Have you verified that the metadata properties of each new query is set appropriately?
Do all the unit tests contain both "COMPLIANT" and "NON_COMPLIANT" cases?
Are the alert messages properly formatted and consistent with the style guide?
Have you run the queries on OpenPilot and verified that the performance and results are acceptable?
As a rule of thumb, predicates specific to the query should take no more than 1 minute, and for simple queries be under 10 seconds. If this is not the case, this should be highlighted and agreed in the code review process.
Does the query have an appropriate level of in-query comments/documentation?
Have you considered/identified possible edge cases?
Does the query not reinvent features in the standard library?
Can the query be simplified further (not golfed!)

…tions.

Copilot

Pull request overview

Adds a new MISRA C++:2023 query implementation for RULE-28-6-4 (requiring the return value of std::remove, std::remove_if, std::unique, and empty to be used), wiring it into the rule packaging/exclusions framework and providing unit tests plus supporting standard-library test stubs.

Changes:

Registers RULE-28-6-4 under a new DeadCode11 query package and hooks it into the exclusions metadata system.
Adds the RULE-28-6-4 query (PotentiallyErroneousContainerUsage.ql) and corresponding unit tests/expected results.
Extends the C++ standard-library test stubs to declare std::empty and required container/algorithm APIs used by tests.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
rules.csv	Switches RULE-28-6-4 to the new `DeadCode11` package.
rule_packages/cpp/DeadCode11.json	Declares package metadata for RULE-28-6-4 query.
cpp/misra/src/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.ql	Implements the query logic for detecting unused results.
cpp/misra/test/rules/RULE-28-6-4/test.cpp	Adds compliant/non-compliant test cases.
cpp/misra/test/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.qlref	Hooks the test to the query.
cpp/misra/test/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.expected	Adds expected findings.
cpp/common/test/includes/standard-library/*	Updates/introduces test stubs for `std::empty`, `erase`, and algorithm declarations.
cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll	Registers the new `DeadCode11` package in the query-metadata union.
cpp/common/src/codingstandards/cpp/exclusions/cpp/DeadCode11.qll	Adds the autogenerated `DeadCode11` exclusion/metadata module.

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Copilot · 2026-02-18T23:01:49Z

cpp/misra/src/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.ql

+import cpp
+import codingstandards.cpp.misra
+


This query file is missing the standard CodeQL metadata header (e.g. @id, @name, @description, severity/tags). The exclusions metadata in DeadCode11.qll expects an @id of cpp/misra/potentially-erroneous-container-usage, so without metadata this query may not be packaged/identified correctly and may break rule metadata generation.

See below for a potential fix:

@ -1,3 +1,14 @@ /** * @id cpp/misra/potentially-erroneous-container-usage * @name MISRA C++ 2008 rule 28-6-4 - Potentially erroneous container usage * @description Flags calls to standard library container-related functions such as * std::remove, std::remove_if, std::unique, or empty where the * result of the call is not used. * @kind problem * @problem.severity warning * @precision medium * @tags cpp misra reliability maintainability */

Copilot · 2026-02-18T23:01:50Z

cpp/misra/src/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.ql

isRemoveOrUniqueCall matches any std::remove by name/namespace, which can include non-algorithm overloads like std::remove(const char*) from <cstdio> (and potentially other remove functions). This will create false positives unrelated to the iterator-returning algorithm. Consider constraining to the algorithm overload set (e.g., by checking parameter count/types/return type) rather than just the unqualified name.

Suggested change

exists(string name | name = fc.getTarget().getName() |

name = "remove" or

name = "remove_if" or

name = "unique"

) and

fc.getTarget().hasQualifiedName("std", _)

exists(Function f, string name |

f = fc.getTarget() and

f.hasQualifiedName("std", _) and

name = f.getName() and

(

name = "remove" and f.getNumberOfParameters() >= 2 or

name = "remove_if" and f.getNumberOfParameters() >= 2 or

name = "unique" and f.getNumberOfParameters() >= 2

)

)

Copilot · 2026-02-18T23:01:50Z

cpp/misra/src/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.ql

isEmptyCall currently flags any member function named empty (instanceof MemberFunction) regardless of the declaring type/namespace. That will report on user-defined APIs like MyType::empty() even though RULE-28 is about standard library usage. Restrict this to standard-library containers (e.g., member functions whose declaring type is in std / recognized STL container types) plus std::empty.

Suggested change

predicate isEmptyCall(FunctionCall fc) {

fc.getTarget().getName() = "empty" and

(

fc.getTarget().hasQualifiedName("std", "empty") or

fc.getTarget() instanceof MemberFunction

/** Returns true if `fc` is a call to a member `empty` function of a type in namespace `std`. */

predicate isStdContainerEmptyMember(FunctionCall fc) {

fc.getTarget() instanceof MemberFunction and

fc.getTarget().getName() = "empty" and

exists(Type t |

fc.getTarget().getDeclaringType() = t and

t.getNamespace().getName() = "std"

)

}

predicate isEmptyCall(FunctionCall fc) {

fc.getTarget().getName() = "empty" and

(

fc.getTarget().hasQualifiedName("std", "empty") or

isStdContainerEmptyMember(fc)

Copilot · 2026-02-18T23:01:50Z

cpp/misra/src/rules/RULE-28-6-4/PotentiallyErroneousContainerUsage.ql

+from FunctionCall fc, string message
+where
+  not isExcluded(fc, DeadCode11Package::potentiallyErroneousContainerUsageQuery()) and
+  exists(ExprStmt es | es.getExpr() = fc) and


The unused-result check only matches when the call expression is exactly the expression statement (es.getExpr() = fc). This misses common “discard result” patterns like static_cast<void>(std::remove(...)) or wrapping the call in a comma operator/parentheses. If the rule intends to catch deliberate discards, consider using a more general predicate for “return value is ignored” that also covers cast-to-void and similar wrappers.

Suggested change

exists(ExprStmt es | es.getExpr() = fc) and

not fc.isResultUsed() and

Implement Rule 28-6-4, require use of std::remove_if and similar func…

46cb4ff

…tions.

Copilot AI review requested due to automatic review settings February 18, 2026 22:56

Copilot started reviewing on behalf of MichaelRFairhurst February 18, 2026 22:56 View session

Copilot AI reviewed Feb 18, 2026

View reviewed changes

MichaelRFairhurst added 3 commits February 18, 2026 15:04

Regenerate ql query header

5d7db89

Copilot feedback

54418e4

Add default ctor to deque which was breaking tests.

b44c675

Provide feedback

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Implement Rule 28-6-4, require use of std::remove_if and similar functions#1046

Implement Rule 28-6-4, require use of std::remove_if and similar functions#1046
MichaelRFairhurst wants to merge 4 commits intomainfrom
michaelrfairhurst/implement-deadcode-11-use-result-of-remove-algorithms-etc

MichaelRFairhurst commented Feb 18, 2026

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-  exists(string name | name = fc.getTarget().getName() |
-    name = "remove" or
-    name = "remove_if" or
-    name = "unique"
-  ) and
-  fc.getTarget().hasQualifiedName("std", _)
+  exists(Function f, string name |
+    f = fc.getTarget() and
+    f.hasQualifiedName("std", _) and
+    name = f.getName() and
+    (
+      name = "remove"     and f.getNumberOfParameters() >= 2 or
+      name = "remove_if"  and f.getNumberOfParameters() >= 2 or
+      name = "unique"     and f.getNumberOfParameters() >= 2
+    )
+  )

-predicate isEmptyCall(FunctionCall fc) {
-  fc.getTarget().getName() = "empty" and
-  (
-    fc.getTarget().hasQualifiedName("std", "empty") or
-    fc.getTarget() instanceof MemberFunction
+/** Returns true if `fc` is a call to a member `empty` function of a type in namespace `std`. */
+predicate isStdContainerEmptyMember(FunctionCall fc) {
+  fc.getTarget() instanceof MemberFunction and
+  fc.getTarget().getName() = "empty" and
+  exists(Type t |
+    fc.getTarget().getDeclaringType() = t and
+    t.getNamespace().getName() = "std"
+  )
+}
+predicate isEmptyCall(FunctionCall fc) {
+  fc.getTarget().getName() = "empty" and
+  (
+    fc.getTarget().hasQualifiedName("std", "empty") or
+    isStdContainerEmptyMember(fc)

	exists(ExprStmt es \| es.getExpr() = fc) and
	not fc.isResultUsed() and

		import cpp
		import codingstandards.cpp.misra

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MichaelRFairhurst commented Feb 18, 2026

Description

Change request type

Rules with added or modified queries

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Query development review checklist

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