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Merge pull request #8611 from github/smowton/doc/switch-expr-accessors

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Java: make SwitchCase.getRuleExpression/Statement more consistent
This commit is contained in:
Anders Schack-Mulligen
2022-04-06 11:16:40 +02:00
committed by GitHub
parent 31ec2988df 81e60eb145
commit d0b5b99e74
5 changed files with 61 additions and 2 deletions
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18
java/ql/lib/semmle/code/java/Statement.qll
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@@ -438,13 +438,27 @@ class SwitchCase extends Stmt, @case {
/**
* Gets the expression on the right-hand side of the arrow, if any.
*
* Note, this predicate gets a value when this switch case is of the form
* `case e1 -> e2`, where `e2` is neither a block nor a throw statement.
* This predicate is mutually exclusive with `getRuleStatement`.
*/
Expr getRuleExpression() { result.getParent() = this and result.getIndex() = -1 }
Expr getRuleExpression() {
result.getParent() = this and result.getIndex() = -1
or
exists(ExprStmt es | es.getParent() = this and es.getIndex() = -1 | result = es.getExpr())
}
/**
* Gets the statement on the right-hand side of the arrow, if any.
*
* Note, this predicate gets a value when this switch case is of the form
* `case e1 -> { s1; s2; ... }` or `case e1 -> throw ...`.
* This predicate is mutually exclusive with `getRuleExpression`.
*/
Stmt getRuleStatement() { result.getParent() = this and result.getIndex() = -1 }
Stmt getRuleStatement() {
result.getParent() = this and result.getIndex() = -1 and not result instanceof ExprStmt
}
}
/** A constant `case` of a switch statement. */

5
java/ql/src/change-notes/2022-04-01-switch-rule-expressions.md Normal file
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@@ -0,0 +1,5 @@
---
category: minorAnalysis
---
* The `SwitchCase.getRuleExpression()` predicate now gets expressions for case rules with an expression on the right-hand side of the arrow belonging to both `SwitchStmt` and `SwitchExpr`, and the corresponding `getRuleStatement()` no longer returns an `ExprStmt` in either case. Previously `SwitchStmt` and `SwitchExpr` behaved differently in
this respect.

23
java/ql/test/library-tests/dataflow/switchexpr/TestSwitchExprStmtConsistency.java Normal file
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@@ -0,0 +1,23 @@
public class TestSwitchExprStmtConsistency {
static int f() { return 0; }
public static void test(int x) {
// Test that getRuleExpression() and getRuleStatement() behave alike for switch expressions and statements using arrow rules.
switch(x) {
case 1 -> f();
case 2 -> f();
default -> f();
}
int result = switch(x) {
case 1 -> f();
case 2 -> f();
default -> f();
};
}
}

12
java/ql/test/library-tests/dataflow/switchexpr/switchcasearrows.expected Normal file
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@@ -0,0 +1,12 @@
exprs
| TestSwitchExpr.java:9:13:9:41 | case ... | TestSwitchExpr.java:9:43:9:46 | null |
| TestSwitchExpr.java:10:13:10:22 | default | TestSwitchExpr.java:10:24:10:25 | x1 |
| TestSwitchExprStmtConsistency.java:10:7:10:15 | case ... | TestSwitchExprStmtConsistency.java:10:17:10:19 | f(...) |
| TestSwitchExprStmtConsistency.java:11:7:11:15 | case ... | TestSwitchExprStmtConsistency.java:11:17:11:19 | f(...) |
| TestSwitchExprStmtConsistency.java:12:7:12:16 | default | TestSwitchExprStmtConsistency.java:12:18:12:20 | f(...) |
| TestSwitchExprStmtConsistency.java:16:7:16:15 | case ... | TestSwitchExprStmtConsistency.java:16:17:16:19 | f(...) |
| TestSwitchExprStmtConsistency.java:17:7:17:15 | case ... | TestSwitchExprStmtConsistency.java:17:17:17:19 | f(...) |
| TestSwitchExprStmtConsistency.java:18:7:18:16 | default | TestSwitchExprStmtConsistency.java:18:18:18:20 | f(...) |
stmts
| TestSwitchExpr.java:13:13:13:28 | case ... | TestSwitchExpr.java:13:30:13:42 | { ... } |
| TestSwitchExpr.java:14:13:14:22 | default | TestSwitchExpr.java:14:24:14:52 | throw ... |

5
java/ql/test/library-tests/dataflow/switchexpr/switchcasearrows.ql Normal file
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@@ -0,0 +1,5 @@
import java
query predicate exprs(SwitchCase sc, Expr e) { e = sc.getRuleExpression() }
query predicate stmts(SwitchCase sc, Stmt s) { s = sc.getRuleStatement() }