Bug 21288 – Wrong context pointer for alias this function

struct A { int p; } struct B { A a() { return A.init; } alias a this; } struct C { void foo() { static assert(B.p.stringof == "p"); // Error: this for s needs to be type B not type C } } void foo() { static assert(B.p.stringof == "p"); // totally fine }

Wait, is this code even valid ? Here in `C.foo` & `foo` you are calling `B.p`, as a shortcut for `B.a.p`, but `a()` is not static, hence you should not be able to do that. Indeed if you change the expression to `B.a.p` it gives you a proper error message. So the second case is an accept-invalid, and the first case could use with a better error message.

It feels like it should be valid. If there is an `alias this` you should really have to know whether something is in `B` or `A`. Since you can do things like `A.p.stringof` or `__traits(getAttributes, A.p)` which requires a symbol, you should probably also be able to do `B.p.stringof` or `__traits(getAttributes, B.p)`.

Right, because it's `stringof`. Just tested and it also trigggers with `__traits(identifier)`. A workaround for this issue would be to use the following: ``` static assert(__traits(identifier, typeof(B.init.a()).p) == "p"); ``` Which works as expected.

@RazvanN7 created dlang/dmd pull request #14969 "Fix Issue 21288 & 10886 - incorrect this pointer" fixing this issue: - Fix Issue 21288 & 10886 - incorrect this pointer https://github.com/dlang/dmd/pull/14969

dlang/dmd pull request #14969 "Fix Issue 21288 & 10886 - incorrect this pointer" was merged into stable: - 30a91c21347eaaebd8b27bb4598726422110c555 by RazvanN7: Fix Issue 21288 & 10886 - incorrect this pointer https://github.com/dlang/dmd/pull/14969

dlang/dmd pull request #14992 "merge stable" was merged into master: - 141c5683f69d5a483d6f1647950249510a025961 by Razvan Nitu: Fix Issue 21288 & 10886 - incorrect this pointer (#14969) https://github.com/dlang/dmd/pull/14992