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Support switch cases with binding patterns

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This commit is contained in:
Chris Smowton
2023-10-18 18:40:47 +01:00
parent fefc02d650
commit f4b45fa511
8 changed files with 279 additions and 52 deletions
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4
java/ql/consistency-queries/children.ql
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@@ -46,7 +46,9 @@ predicate gapInChildren(Element e, int i) {
// value should be, because kotlinc doesn't load annotation defaults and we
// want to leave a space for another extractor to fill in the default if it
// is able.
not e instanceof Annotation
not e instanceof Annotation and
// Pattern case statements legitimately have a TypeAccess (-2) and a pattern (0) but not a rule (-1)
not (i = -1 and e instanceof PatternCase and not e.(PatternCase).isRule())
}
predicate lateFirstChild(Element e, int i) {

66
java/ql/lib/semmle/code/java/ControlFlowGraph.qll
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@@ -434,6 +434,15 @@ private module ControlFlowGraphImpl {
)
}
/**
* Gets a SwitchCase's successor SwitchCase, if any.
*/
private predicate nextSwitchCase(SwitchCase pred, SwitchCase succ) {
exists(SwitchExpr se, int idx | se.getCase(idx) = pred and se.getCase(idx + 1) = succ)
or
exists(SwitchStmt ss, int idx | ss.getCase(idx) = pred and ss.getCase(idx + 1) = succ)
}
/**
* Expressions and statements with CFG edges in post-order AST traversal.
*
@@ -467,7 +476,8 @@ private module ControlFlowGraphImpl {
this instanceof NotInstanceOfExpr
or
this instanceof LocalVariableDeclExpr and
not this = any(InstanceOfExpr ioe).getLocalVariableDeclExpr()
not this = any(InstanceOfExpr ioe).getLocalVariableDeclExpr() and
not this = any(PatternCase pc).getDecl()
or
this instanceof StringTemplateExpr
or
@@ -493,7 +503,9 @@ private module ControlFlowGraphImpl {
or
this.(BlockStmt).getNumStmt() = 0
or
this instanceof SwitchCase and not this.(SwitchCase).isRule()
this instanceof SwitchCase and
not this.(SwitchCase).isRule() and
not this instanceof PatternCase
or
this instanceof EmptyStmt
or
@@ -887,6 +899,14 @@ private module ControlFlowGraphImpl {
else completion = caseCompletion
)
or
// The last node in a case could always be a failing pattern check.
last = n.(PatternCase) and
completion = basicBooleanCompletion(false)
or
// The last node in a non-rule case is its variable declaration.
last = n.(PatternCase).getDecl() and
completion = NormalCompletion()
or
// the last statement of a synchronized statement is the last statement of its body
last(n.(SynchronizedStmt).getBlock(), last, completion)
or
@@ -1201,8 +1221,14 @@ private module ControlFlowGraphImpl {
// From the entry point control is transferred first to the expression...
n = switch and result = first(switch.getExpr())
or
// ...and then to one of the cases.
last(switch.getExpr(), n, completion) and result = first(switch.getACase())
// ...and then for a vanilla switch to any case, or for a pattern switch to the first one.
exists(SwitchCase firstExecutedCase |
if switch.getACase() instanceof PatternCase
then firstExecutedCase = switch.getCase(0)
else firstExecutedCase = switch.getACase()
|
last(switch.getExpr(), n, completion) and result = first(firstExecutedCase)
)
or
// Statements within a switch body execute sequentially.
exists(int i |
@@ -1216,7 +1242,13 @@ private module ControlFlowGraphImpl {
n = switch and result = first(switch.getExpr())
or
// ...and then to one of the cases.
last(switch.getExpr(), n, completion) and result = first(switch.getACase())
exists(SwitchCase firstExecutedCase |
if switch.getACase() instanceof PatternCase
then firstExecutedCase = switch.getCase(0)
else firstExecutedCase = switch.getACase()
|
last(switch.getExpr(), n, completion) and result = first(firstExecutedCase)
)
or
// Statements within a switch body execute sequentially.
exists(int i |
@@ -1224,11 +1256,29 @@ private module ControlFlowGraphImpl {
)
)
or
// Edge from rule SwitchCases to their body, after any variable assignment if applicable.
// No edges in a non-rule SwitchCase - the constant expression in a ConstCase isn't included in the CFG.
exists(SwitchCase case | completion = NormalCompletion() |
n = case and result = first(case.getRuleExpression())
exists(SwitchCase case, ControlFlowNode preBodyNode |
completion = NormalCompletion() and
if case instanceof PatternCase
then preBodyNode = case.(PatternCase).getDecl()
else preBodyNode = case
|
n = preBodyNode and result = first(case.getRuleExpression())
or
n = case and result = first(case.getRuleStatement())
n = preBodyNode and result = first(case.getRuleStatement())
)
or
// A pattern case conducts a type test, then branches to either the next case or the assignment.
exists(PatternCase case |
n = case and
(
completion = basicBooleanCompletion(false) and
nextSwitchCase(case, result)
or
completion = basicBooleanCompletion(true) and
result = case.getDecl()
)
)
or
// Yield

40
java/ql/lib/semmle/code/java/Expr.qll
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@@ -1509,17 +1509,28 @@ class SwitchExpr extends Expr, StmtParent, @switchexpr {
*/
Stmt getStmt(int index) { result = this.getAStmt() and result.getIndex() = index }
/**
* Gets the `i`th case of this `switch` expression,
* which may be either a normal `case` or a `default`.
*/
SwitchCase getCase(int i) {
result = rank[i](SwitchCase case, int idx | case.isNthChildOf(this, idx) | case order by idx)
}
/**
* Gets a case of this `switch` expression,
* which may be either a normal `case` or a `default`.
*/
SwitchCase getACase() { result = this.getAConstCase() or result = this.getDefaultCase() }
SwitchCase getACase() { result.getParent() = this }
/** Gets a (non-default) `case` of this `switch` expression. */
ConstCase getAConstCase() { result.getParent() = this }
ConstCase getAConstCase() { result = this.getACase() }
/** Gets a (non-default) pattern `case` of this `switch` expression. */
PatternCase getAPatternCase() { result = this.getACase() }
/** Gets the `default` case of this switch expression, if any. */
DefaultCase getDefaultCase() { result.getParent() = this }
DefaultCase getDefaultCase() { result = this.getACase() }
/** Gets the expression of this `switch` expression. */
Expr getExpr() { result.getParent() = this }
@@ -1592,7 +1603,9 @@ class NotInstanceOfExpr extends Expr, @notinstanceofexpr {
* A local variable declaration expression.
*
* Contexts in which such expressions may occur include
* local variable declaration statements and `for` loops.
* local variable declaration statements, `for` loops,
* and binding patterns such as `if (x instanceof T t)` and
* `case String s:`.
*/
class LocalVariableDeclExpr extends Expr, @localvariabledeclexpr {
/** Gets an access to the variable declared by this local variable declaration expression. */
@@ -1612,18 +1625,33 @@ class LocalVariableDeclExpr extends Expr, @localvariabledeclexpr {
exists(EnhancedForStmt efs | efs.getVariable() = this | result.isNthChildOf(efs, -1))
or
exists(InstanceOfExpr ioe | this.getParent() = ioe | result.isNthChildOf(ioe, 1))
or
exists(PatternCase pc | this.getParent() = pc | result.isNthChildOf(pc, -2))
}
/** Gets the name of the variable declared by this local variable declaration expression. */
string getName() { result = this.getVariable().getName() }
/** Gets the switch statement or expression whose pattern declares this identifier, if any. */
StmtParent getAssociatedSwitch() {
result = this.getParent().(PatternCase).getParent()
}
/** Holds if this is a declaration stemming from a pattern switch case. */
predicate hasAssociatedSwitch() {
exists(this.getAssociatedSwitch())
}
/** Gets the initializer expression of this local variable declaration expression, if any. */
Expr getInit() { result.isNthChildOf(this, 0) }
Expr getInit() {
result.isNthChildOf(this, 0)
}
/** Holds if this variable declaration implicitly initializes the variable. */
predicate hasImplicitInit() {
exists(CatchClause cc | cc.getVariable() = this) or
exists(EnhancedForStmt efs | efs.getVariable() = this)
exists(EnhancedForStmt efs | efs.getVariable() = this) or
this.hasAssociatedSwitch()
}
/** Gets a printable representation of this expression. */

43
java/ql/lib/semmle/code/java/Statement.qll
View File

@@ -382,17 +382,28 @@ class SwitchStmt extends Stmt, @switchstmt {
*/
Stmt getStmt(int index) { result = this.getAStmt() and result.getIndex() = index }
/**
* Gets the `i`th case of this `switch` statement,
* which may be either a normal `case` or a `default`.
*/
SwitchCase getCase(int i) {
result = rank[i](SwitchCase case, int idx | case.isNthChildOf(this, idx) | case order by idx)
}
/**
* Gets a case of this `switch` statement,
* which may be either a normal `case` or a `default`.
*/
SwitchCase getACase() { result = this.getAConstCase() or result = this.getDefaultCase() }
SwitchCase getACase() { result.getParent() = this }
/** Gets a (non-default) `case` of this `switch` statement. */
ConstCase getAConstCase() { result.getParent() = this }
/** Gets a (non-default) constant `case` of this `switch` statement. */
ConstCase getAConstCase() { result = this.getACase() }
/** Gets a (non-default) pattern `case` of this `switch` statement. */
PatternCase getAPatternCase() { result = this.getACase() }
/** Gets the `default` case of this switch statement, if any. */
DefaultCase getDefaultCase() { result.getParent() = this }
DefaultCase getDefaultCase() { result = this.getACase() }
/** Gets the expression of this `switch` statement. */
Expr getExpr() { result.getParent() = this }
@@ -464,15 +475,15 @@ class SwitchCase extends Stmt, @case {
/** A constant `case` of a switch statement. */
class ConstCase extends SwitchCase {
ConstCase() { exists(Expr e | e.getParent() = this | e.getIndex() >= 0) }
ConstCase() { exists(Literal e | e.getParent() = this and e.getIndex() >= 0) }
/** Gets the `case` constant at index 0. */
Expr getValue() { result.getParent() = this and result.getIndex() = 0 }
Expr getValue() { result.isNthChildOf(this, 0) }
/**
* Gets the `case` constant at the specified index.
*/
Expr getValue(int i) { result.getParent() = this and result.getIndex() = i and i >= 0 }
Expr getValue(int i) { result.isNthChildOf(this, i) and i >= 0 }
override string pp() { result = "case ..." }
@@ -483,6 +494,24 @@ class ConstCase extends SwitchCase {
override string getAPrimaryQlClass() { result = "ConstCase" }
}
/** A pattern case of a `switch` statement */
class PatternCase extends SwitchCase {
LocalVariableDeclExpr patternVar;
PatternCase() { patternVar.isNthChildOf(this, 0) }
/** Gets the variable declared by this pattern case. */
LocalVariableDeclExpr getDecl() { result.isNthChildOf(this, 0) }
override string pp() { result = "case T t ..." }
override string toString() { result = "case T t ..." }
override string getHalsteadID() { result = "PatternCase" }
override string getAPrimaryQlClass() { result = "PatternCase" }
}
/** A `default` case of a `switch` statement */
class DefaultCase extends SwitchCase {
DefaultCase() { not exists(Expr e | e.getParent() = this | e.getIndex() >= 0) }

9
java/ql/lib/semmle/code/java/dispatch/ObjFlow.qll
View File

@@ -80,6 +80,15 @@ private predicate step(Node n1, Node n2) {
for.getVariable() = def.(BaseSsaUpdate).getDefiningExpr() and
for.getExpr() = n1.asExpr()
)
or
exists(PatternCase pc |
pc.getDecl() = def.(BaseSsaUpdate).getDefiningExpr() and
(
pc.getSwitch().getExpr() = n1.asExpr()
or
pc.getSwitchExpr().getExpr() = n1.asExpr()
)
)
|
v.getAnUltimateDefinition() = def and
v.getAUse() = n2.asExpr()

30
java/ql/test/library-tests/printAst/A.java
View File

@@ -50,6 +50,34 @@ class A {
if (thing instanceof String s) {
throw new RuntimeException(s);
}
switch (thing) {
case String s -> System.out.println(s);
case Integer i -> System.out.println("An integer: " + i);
default -> { }
}
switch (thing) {
case String s:
System.out.println(s);
break;
case Integer i:
System.out.println("An integer:" + i);
break;
default:
break;
}
var thingAsString = switch(thing) {
case String s -> s;
case Integer i -> "An integer: " + i;
default -> "Something else";
};
var thingAsString2 = switch(thing) {
case String s:
yield s;
case Integer i:
yield "An integer: " + i;
default:
yield "Something else";
};
}
}
catch (RuntimeException rte) {
@@ -70,4 +98,4 @@ class A {
* Javadoc for fields
*/
int i, j, k;
}
}

137
java/ql/test/library-tests/printAst/PrintAst.expected
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@@ -119,36 +119,117 @@ A.java:
# 51| 0: [ClassInstanceExpr] new RuntimeException(...)
# 51| -3: [TypeAccess] RuntimeException
# 51| 0: [VarAccess] s
# 55| 0: [CatchClause] catch (...)
# 53| 2: [SwitchStmt] switch (...)
# 53| -1: [VarAccess] thing
# 54| 0: [PatternCase] case T t ...
# 54| -2: [TypeAccess] String
# 54| -1: [ExprStmt] <Expr>;
# 54| 0: [MethodAccess] println(...)
# 54| -1: [VarAccess] System.out
# 54| -1: [TypeAccess] System
# 54| 0: [VarAccess] s
# 54| 0: [LocalVariableDeclExpr] s
# 55| 1: [PatternCase] case T t ...
# 55| -2: [TypeAccess] Integer
# 55| -1: [ExprStmt] <Expr>;
# 55| 0: [MethodAccess] println(...)
# 55| -1: [VarAccess] System.out
# 55| -1: [TypeAccess] System
# 55| 0: [AddExpr] ... + ...
# 55| 0: [StringLiteral] "An integer: "
# 55| 1: [VarAccess] i
# 55| 0: [LocalVariableDeclExpr] i
# 56| 2: [DefaultCase] default
# 56| -1: [BlockStmt] { ... }
# 58| 3: [SwitchStmt] switch (...)
# 58| -1: [VarAccess] thing
# 59| 0: [PatternCase] case T t ...
# 59| -2: [TypeAccess] String
# 59| 0: [LocalVariableDeclExpr] s
# 60| 1: [ExprStmt] <Expr>;
# 60| 0: [MethodAccess] println(...)
# 60| -1: [VarAccess] System.out
# 60| -1: [TypeAccess] System
# 60| 0: [VarAccess] s
# 61| 2: [BreakStmt] break
# 62| 3: [PatternCase] case T t ...
# 62| -2: [TypeAccess] Integer
# 62| 0: [LocalVariableDeclExpr] i
# 63| 4: [ExprStmt] <Expr>;
# 63| 0: [MethodAccess] println(...)
# 63| -1: [VarAccess] System.out
# 63| -1: [TypeAccess] System
# 63| 0: [AddExpr] ... + ...
# 63| 0: [StringLiteral] "An integer:"
# 63| 1: [VarAccess] i
# 64| 5: [BreakStmt] break
# 65| 6: [DefaultCase] default
# 66| 7: [BreakStmt] break
# 68| 4: [LocalVariableDeclStmt] var ...;
# 68| 1: [LocalVariableDeclExpr] thingAsString
# 68| 0: [SwitchExpr] switch (...)
# 68| -1: [VarAccess] thing
# 69| 0: [PatternCase] case T t ...
# 69| -2: [TypeAccess] String
# 69| -1: [VarAccess] s
# 69| 0: [LocalVariableDeclExpr] s
# 70| 1: [PatternCase] case T t ...
# 70| -2: [TypeAccess] Integer
# 70| -1: [AddExpr] ... + ...
# 70| 0: [StringLiteral] "An integer: "
# 70| 1: [VarAccess] i
# 70| 0: [LocalVariableDeclExpr] i
# 71| 2: [DefaultCase] default
# 71| -1: [StringLiteral] "Something else"
# 73| 5: [LocalVariableDeclStmt] var ...;
# 73| 1: [LocalVariableDeclExpr] thingAsString2
# 73| 0: [SwitchExpr] switch (...)
# 73| -1: [VarAccess] thing
# 74| 0: [PatternCase] case T t ...
# 74| -2: [TypeAccess] String
# 74| 0: [LocalVariableDeclExpr] s
# 75| 1: [YieldStmt] yield ...
# 75| 0: [VarAccess] s
# 76| 2: [PatternCase] case T t ...
# 76| -2: [TypeAccess] Integer
# 76| 0: [LocalVariableDeclExpr] i
# 77| 3: [YieldStmt] yield ...
# 77| 0: [AddExpr] ... + ...
# 77| 0: [StringLiteral] "An integer: "
# 77| 1: [VarAccess] i
# 78| 4: [DefaultCase] default
# 79| 5: [YieldStmt] yield ...
# 79| 0: [StringLiteral] "Something else"
# 83| 0: [CatchClause] catch (...)
#-----| 0: (Single Local Variable Declaration)
# 55| 0: [TypeAccess] RuntimeException
# 55| 1: [LocalVariableDeclExpr] rte
# 55| 1: [BlockStmt] { ... }
# 56| 0: [ReturnStmt] return ...
# 60| 10: [Class] E
# 64| 3: [FieldDeclaration] E A;
# 83| 0: [TypeAccess] RuntimeException
# 83| 1: [LocalVariableDeclExpr] rte
# 83| 1: [BlockStmt] { ... }
# 84| 0: [ReturnStmt] return ...
# 88| 10: [Class] E
# 92| 3: [FieldDeclaration] E A;
#-----| -3: (Javadoc)
# 61| 1: [Javadoc] /** Javadoc for enum constant */
# 62| 0: [JavadocText] Javadoc for enum constant
# 64| -1: [TypeAccess] E
# 64| 0: [ClassInstanceExpr] new E(...)
# 64| -3: [TypeAccess] E
# 65| 4: [FieldDeclaration] E B;
# 89| 1: [Javadoc] /** Javadoc for enum constant */
# 90| 0: [JavadocText] Javadoc for enum constant
# 92| -1: [TypeAccess] E
# 92| 0: [ClassInstanceExpr] new E(...)
# 92| -3: [TypeAccess] E
# 93| 4: [FieldDeclaration] E B;
#-----| -3: (Javadoc)
# 61| 1: [Javadoc] /** Javadoc for enum constant */
# 62| 0: [JavadocText] Javadoc for enum constant
# 65| -1: [TypeAccess] E
# 65| 0: [ClassInstanceExpr] new E(...)
# 65| -3: [TypeAccess] E
# 66| 5: [FieldDeclaration] E C;
# 89| 1: [Javadoc] /** Javadoc for enum constant */
# 90| 0: [JavadocText] Javadoc for enum constant
# 93| -1: [TypeAccess] E
# 93| 0: [ClassInstanceExpr] new E(...)
# 93| -3: [TypeAccess] E
# 94| 5: [FieldDeclaration] E C;
#-----| -3: (Javadoc)
# 61| 1: [Javadoc] /** Javadoc for enum constant */
# 62| 0: [JavadocText] Javadoc for enum constant
# 66| -1: [TypeAccess] E
# 66| 0: [ClassInstanceExpr] new E(...)
# 66| -3: [TypeAccess] E
# 72| 11: [FieldDeclaration] int i, ...;
# 89| 1: [Javadoc] /** Javadoc for enum constant */
# 90| 0: [JavadocText] Javadoc for enum constant
# 94| -1: [TypeAccess] E
# 94| 0: [ClassInstanceExpr] new E(...)
# 94| -3: [TypeAccess] E
# 100| 11: [FieldDeclaration] int i, ...;
#-----| -3: (Javadoc)
# 69| 1: [Javadoc] /** Javadoc for fields */
# 70| 0: [JavadocText] Javadoc for fields
# 72| -1: [TypeAccess] int
# 97| 1: [Javadoc] /** Javadoc for fields */
# 98| 0: [JavadocText] Javadoc for fields
# 100| -1: [TypeAccess] int

2
java/ql/test/library-tests/printAst/options
View File

@@ -1 +1 @@
//semmle-extractor-options: --javac-args -source 17 -target 17
//semmle-extractor-options: --javac-args --release 21