Skip to content

C++: Fix join-order problem in getNextSwitchCase #21765

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

Merged
jketema merged 4 commits into from
Apr 28, 2026
Merged

C++: Fix join-order problem in getNextSwitchCase #21765

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
fa8c1d6
C++: Add a `getSwitchCase` predicate to `SwitchStmt`
jketema Apr 28, 2026
f634b32
C++: Fix join-order problem in `getNextSwitchCase`
jketema Apr 28, 2026
0bc23c3
C++: Match example with text
jketema Apr 28, 2026
29dd56f
C++: Make formatting of `switch` statement examples more uniform
jketema Apr 28, 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 cpp/ql/lib/change-notes/2026-03-28-switch-stmt.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
---
category: feature
---
* A new predicate `getSwitchCase` was added to the `SwitchStmt` class, which yields the `n`th `case` statement from a `switch` statement.
79 changes: 49 additions & 30 deletions cpp/ql/lib/semmle/code/cpp/stmts/Stmt.qll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1412,9 +1412,9 @@ private int indexOfSwitchCaseRank(BlockStmt b, int rnk) {
* switch (i)
* {
* case 5:
* ...
* ...
* default:
* ...
* ...
* }
* ```
*/
Expand Down Expand Up @@ -1516,8 +1516,10 @@ class SwitchCase extends Stmt, @stmt_switch_case {
* which has result `default:`, which has no result.
*/
SwitchCase getNextSwitchCase() {
result.getSwitchStmt() = this.getSwitchStmt() and
result.getChildNum() = this.getChildNum() + 1
exists(SwitchStmt s, int n |
this = s.getSwitchCase(n) and
result = s.getSwitchCase(n + 1)
)
}

/**
Expand Down Expand Up @@ -1707,9 +1709,9 @@ class SwitchCase extends Stmt, @stmt_switch_case {
* switch (i)
* {
* case 5:
* ...
* ...
* default:
* ...
* ...
* }
* ```
*/
Expand All @@ -1731,9 +1733,9 @@ class DefaultCase extends SwitchCase {
* switch (i)
* {
* case 5:
* ...
* ...
* default:
* ...
* ...
* }
* ```
*/
Expand Down Expand Up @@ -1768,10 +1770,10 @@ class SwitchStmt extends ConditionalStmt, @stmt_switch {
* For example, for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
Expand All @@ -1790,20 +1792,20 @@ class SwitchStmt extends ConditionalStmt, @stmt_switch {
* For example, for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
* the result is
* ```
* {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
Expand All @@ -1816,36 +1818,53 @@ class SwitchStmt extends ConditionalStmt, @stmt_switch {
* For example, for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
* the results are `case 1:`, `case 2:` and `default:`.
*/
SwitchCase getASwitchCase() { switch_case(underlyingElement(this), _, unresolveElement(result)) }

/**
* Gets the `n`th 'switch case' statement of this 'switch' statement, where
* `n` is 0-based.
*
* For example, for
* ```
* switch(i) {
* case 5:
* case 6:
* default:
* } * ```
* 0 yields `case 5:`, 1 yields `case 6:`, and 2 yields `default:`.
Copy link
Copy Markdown
Contributor

@IdrissRio IdrissRio Apr 28, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
* 0 yields `case 5:`, 1 yields `case 6:`, and 2 yields `default:`.
* 0 yields `case 1:`, 1 yields `case 2:`, and 2 yields `default:`.

Copy link
Copy Markdown
Contributor Author

@jketema jketema Apr 28, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Fixed by updating the example instead.

*/
SwitchCase getSwitchCase(int n) {
switch_case(underlyingElement(this), n, unresolveElement(result))
}

/**
* Gets the 'default case' statement of this 'switch' statement,
* if any.
*
* For example, for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
* the result is `default:`, but there is no result for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* }
* ```
Expand All @@ -1858,18 +1877,18 @@ class SwitchStmt extends ConditionalStmt, @stmt_switch {
* For example, this holds for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* default:
* default:
* break;
* }
* ```
* but not for
* ```
* switch(i) {
* case 1:
* case 2:
* case 1:
* case 2:
* break;
* }
* ```
Expand Down
Loading