Skip to content

C#: Data flow for property patterns. #22757

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
michaelnebel wants to merge 4 commits into
base: main
Choose a base branch
from
Draft

C#: Data flow for property patterns. #22757

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
00b8de6
C#: Comment in the expected output in property pattern tests and add …
michaelnebel Oct 1, 2026
dcd73f9
C#: Support for data flow via property patterns.
michaelnebel Oct 6, 2026
312e3a7
C#: Update test expected output.
michaelnebel Oct 6, 2026
59612ef
C#: Add change-note.
michaelnebel Oct 6, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions csharp/ql/lib/change-notes/2026-10-06-property-pattern-flow.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* Added support for data flow through property patterns in `is` expressions and `switch` cases.
27 changes: 27 additions & 0 deletions csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2308,6 +2308,31 @@ private predicate readStepDelegateCall(Node node1, ContentSet c, OutNode node2)
)
}

/**
* Holds if data can flow from `node1` to `node2` via a property pattern.
*/
private predicate fieldOrPropertyPatternRead(Node node1, ContentSet c, Node node2) {
exists(PatternExpr pattern, LabeledPatternExpr label, FieldOrProperty f |
node1.asExpr() = pattern and
(
pattern.(RecursivePatternExpr).getPropertyPatterns().getPattern(_) = label
or
pattern.(PropertyPatternExpr).getPattern(_) = label
) and
c = f.getContentSet() and
f.getName() = label.getLabel()
|
node2.asExpr() = label.(RecursivePatternExpr)
or
node2.asExpr() = label.(PropertyPatternExpr)
or
exists(AssignableDefinitions::PatternDefinition lvd |
node2.(AssignableDefinitionNode).getDefinition() = lvd and
label.(BindingPatternExpr).getVariableDeclExpr() = lvd.getDeclaration()
)
)
}

/**
* Holds if data can flow from `node1` to `node2` via a read of content `c`.
*/
Expand All @@ -2319,6 +2344,8 @@ predicate readStep(Node node1, ContentSet c, Node node2) {
or
fieldOrPropertyRead(node1.asExpr(), c, node2.asExpr())
or
fieldOrPropertyPatternRead(node1, c, node2)
or
dynamicPropertyRead(node1.asExpr(), c, node2.asExpr())
or
node2.asExpr().(AwaitExpr).getExpr() = node1.asExpr() and
Expand Down
Loading
Loading