Bug 4407 – Catch wrong argument<->attribute assignments in methods

This is related to bug 3878 , but it is meant to catch a different kind of bug. In my code I have seen two times bugs like: class Foo { int x, y; this(int x_, int y_) { this.x = x; y = y; } } void main() {} In D.learn Byron Heads has found this bug: http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D.learn&article_id=20354 this(string name, string id) { this._name = _name; this._id = id; } So I think the D compiler has to catch such bugs, and refuse such assignments in class/struct member functions. Automatic code generation can sometimes generate useless assignments, but catching common human bugs is more important. It's much simpler to fix code generators than humans.

To keep the language semantics more uniform (instead of special-casing just in methods), all redundant assignments may be flagged as errors: void main() { int x; x = x; // error, redundant assignment }

It's present among the Semantic Errors of Java code in the Google Web Toolkit too: http://code.google.com/intl/en-EN/webtoolkit/tools/codepro/doc/features/audit/audit_rules_com.instantiations.assist.eclipse.auditGroup.semanticErrors.html#com.instantiations.assist.eclipse.audit.redundantAssignment

Another similar class of bugs, suggested by JimBob: class Foo { int m_x; this(int x) { int m_x = x; } }

One example of bug related to x=x; found inside the good QT libs: PassRefPtr<Structure> Structure::getterSetterTransition(Structure* structure) { ... RefPtr<Structure> transition = create( structure->storedPrototype(), structure->typeInfo()); transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity; transition->m_hasGetterSetterProperties = transition->m_hasGetterSetterProperties; transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties; transition->m_specificFunctionThrashCount = structure->m_specificFunctionThrashCount; ... }

*** Issue 9080 has been marked as a duplicate of this issue. ***

Denied by Walter. A shame because this is a common user bug.

(In reply to comment #6) > Denied by Walter. A shame because this is a common user bug. Any comments about the reason?

(In reply to comment #7) > Any comments about the reason? If you don't receive answers here in a day or two, then you probably have to ask again in the main D newsgroup...