Review

Detector:	MuDetect
Target:	project ' closure ' version 114
Misuse:	misuse ' 1 '
Tags:

Misuse Details

Details about the known misuse from the MUBench dataset.

Description:	UnionTypeBuilder.build() returns a JSType that can never be null. Branching on a null check therefore results in dead code.
Fix Description:	Check Node.isNoType() instead. (see diff)
Violation Types:	superfluous/condition/null_check
In File:	com/google/javascript/rhino/jstype/UnionType.java
In Method:	meet(JSType)
Code with Misuse:	class UnionType { JSType meet(JSType that) { UnionTypeBuilder builder = new UnionTypeBuilder(registry); for (JSType alternate : alternates) { if (alternate.isSubtype(that)) { builder.addAlternate(alternate); } } if (that instanceof UnionType) { for (JSType otherAlternate : ((UnionType) that).alternates) { if (otherAlternate.isSubtype(this)) { builder.addAlternate(otherAlternate); } } } else if (that.isSubtype(this)) { builder.addAlternate(that); } JSType result = builder.build(); if (result != null) { return result; } else if (this.isObject() && that.isObject()) { return getNativeType(JSTypeNative.NO_OBJECT_TYPE); } else { return getNativeType(JSTypeNative.NO_TYPE); } } }

Potential Hits

Findings of the detector that identify an anomaly in the same file and method as the known misuse.

Hit	Rank	Confidence	Confidence String	Pattern Examples	Pattern Support	Pattern Violation	Target Environment Mapping
No	1187	8.0175052977208E-6	(pattern violations = 1 / 597)(violation support = 1 / 97)(pattern support = 13 / 28)	closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processSwitchStatement(SwitchStatement);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processVariableDeclaration(VariableDeclaration);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processTryStatement(TryStatement);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processArrayLiteral(ArrayLiteral);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processFunctionNode(FunctionNode)	13
No	1781	2.7287649609787E-6	(pattern violations = 1 / 597)(violation support = 1 / 285)(pattern support = 13 / 28)	closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processSwitchStatement(SwitchStatement);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processVariableDeclaration(VariableDeclaration);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processTryStatement(TryStatement);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processArrayLiteral(ArrayLiteral);closure/114/original-src/com/google/javascript/jscomp/parsing/IRFactory.java#processFunctionNode(FunctionNode)	13
No	747	2.6674167765966E-5	(pattern violations = 1 / 526)(violation support = 1 / 28)(pattern support = 11 / 28)	closure/114/original-src/com/google/javascript/rhino/jstype/RecordType.java#isSubtype(ObjectType, RecordType);closure/114/original-src/com/google/javascript/rhino/jstype/UnionType.java#getRestrictedUnion(JSType);closure/114/original-src/com/google/javascript/rhino/jstype/UnionType.java#meet(JSType);closure/114/original-src/com/google/javascript/rhino/jstype/UnionType.java#getLeastSupertype(JSType);closure/114/original-src/com/google/javascript/rhino/jstype/PrototypeObjectType.java#isSubtype(JSType)	11

Reviewer Name:	sarah
Comment: