Bug 20687 – Allow member function address as const initializer

Code: struct S { void foo(){} } void main() { S i; enum fp = &S.foo; auto dg = &i.foo; assert(fp == dg.funcptr); // Allow this static immutable dgfp = &S.foo; assert(dgfp == dg.funcptr); } You can already use an enum. https://forum.dlang.org/thread/[email protected]

@BorisCarvajal created dlang/dmd pull request #10946 "Fix Issue 20687 - Allow member function address as const initializer" fixing this issue: - Fix Issue 20687 - Allow member function address as const initializer https://github.com/dlang/dmd/pull/10946

dlang/dmd pull request #10946 "Fix Issue 20687 - Allow member function address as const initializer" was merged into stable: - 4ad1a199e2d5a9a0b87b1513e5690b9e29a8ed54 by Boris Carvajal: Fix Issue 20687 - Allow member function address as const initializer https://github.com/dlang/dmd/pull/10946

dlang/dmd pull request #10948 "Revert "Fix Issue 20687 - Allow member function address as const initializer"" was merged into stable: - bb766e125c590249730f967892bda6697b4a648b by Iain Buclaw: Revert "Fix Issue 20687 - Allow member function address as const initializer" https://github.com/dlang/dmd/pull/10948

This has been re-opened, as it is not clear whether we want it to be possible or not. The fact it's possible at runtime could be considered an accept-invalid, instead of this being a reject-valid.

It's very clear to me it should be available at compile time and runtime. Whether it is callable on its own is a matter for debate, but that would be a breaking change. If we made it unavailable at runtime, it is still available with &instance.fun.funcptr. What does funcptr return? If we started disallowing funcptr manipulation, then maybe this becomes invalid, but that is a whole new ball of code breakage that I don't think we want to get into right now. Even if we disallowed creating a variable that accepts such a member-function pointer, a delegate has no type information for it's context pointer, so something like this would still be possible: struct S { int x; void foo() {++x;} } struct T { int *x; void bar() {*x = 5;} } auto s = S(100000); T t; auto dg = &s.foo; dg.funcptr = (&t.bar).funcptr; dg(); // uses s.x as if it were a pointer If we wanted to talk about type safety in this area, the status quo does not cut it. While not type-safe, at least it can be made consistent.

@BorisCarvajal created dlang/dmd pull request #10958 "Fix Issue 20687 - Allow member function address as const initializer" fixing this issue: - Fix Issue 20687 - Allow member function address as const initializer https://github.com/dlang/dmd/pull/10958

@MoonlightSentinel created dlang/dmd pull request #10970 "Merge branch 'master' into stable" fixing this issue: - Fix Issue 20687 - Allow member function address as const initializer - Merge pull request #10946 from BorisCarvajal/mptr_constinit Fix Issue 20687 - Allow member function address as const initializer merged-on-behalf-of: Nicholas Wilson <[email protected]> - Revert "Fix Issue 20687 - Allow member function address as const initializer" https://github.com/dlang/dmd/pull/10970

@MartinNowak created dlang/dmd pull request #11027 "merge stable" fixing this issue: - Fix Issue 20687 - Allow member function address as const initializer - Merge pull request #10946 from BorisCarvajal/mptr_constinit Fix Issue 20687 - Allow member function address as const initializer merged-on-behalf-of: Nicholas Wilson <[email protected]> - Revert "Fix Issue 20687 - Allow member function address as const initializer" https://github.com/dlang/dmd/pull/11027

dlang/dmd pull request #11027 "merge stable" was merged into master: - 4ad1a199e2d5a9a0b87b1513e5690b9e29a8ed54 by Boris Carvajal: Fix Issue 20687 - Allow member function address as const initializer - aba2deaefdd3bb0ce9d3293b715959a6de416679 by The Dlang Bot: Merge pull request #10946 from BorisCarvajal/mptr_constinit Fix Issue 20687 - Allow member function address as const initializer merged-on-behalf-of: Nicholas Wilson <[email protected]> - 1f3245d3241d90f4d74b9398558ddc71d57335c4 by Iain Buclaw: Revert "Fix Issue 20687 - Allow member function address as const initializer" https://github.com/dlang/dmd/pull/11027

dlang/dmd pull request #10958 "Fix Issue 20687 - Allow member function address as const initializer" was merged into master: - 7bcf238b606efcc9808c795447adca9ea47b4e3a by Boris Carvajal: Fix Issue 20687 - Allow member function address as const initializer of static data https://github.com/dlang/dmd/pull/10958