Bug 11720 – Function-local static variables should cause "already defined in another scope" error

import std.stdio; void main(){ struct A{ int x; int x2; } A a; fun(a); } void fun(T)(T a){ foreach(i, member; a.tupleof) { static temp=a.tupleof[i].stringof; string name = a.tupleof[i].stringof[2..$]; writeln(i," ",temp," ",name);//prints 0 a.x x then 1 a.x x2 assert(name==temp[2..$]);//fails } }

This is unrelated bug to tupleof property. compile-time iterated foerach loop is unrolled to multiple scope statements. foreach (T; TypeTuple!(int, double)) { static temp = T.stringof; } // is equivalent to: { static temp = int.stringof; } { static temp = double.stringof; } Then, two static temp variables have exactly same mangled name, so they conflicts and should cause linker error at least. However, all of instantiated code will be placed in COMDAT section, so they incorrectly share the storage. Changed the summary.

(In reply to comment #2) > https://github.com/D-Programming-Language/dmd/pull/2947 Is having it error really the right way to fix this? It looks to me to be an issue with the fact that the bodies of a statically expanded foreach are not specially mangled.

(In reply to comment #3) > (In reply to comment #2) > > https://github.com/D-Programming-Language/dmd/pull/2947 > > Is having it error really the right way to fix this? It looks to me to be an > issue with the fact that the bodies of a statically expanded foreach are not > specially mangled. Yes. In D, function local declarations which are assigned to global symbols cannot have same name because of the mangled name conflict. void main() { { void f() {} } { void f() {} } // Error: declaration f is already defined in another scope in main { struct S {} } { struct S {} } // Error: declaration S is already defined in another scope in main { static int v = 1; } { static int v = 1; } // should be same error }

Looks like a design mistake.

(In reply to comment #5) > Looks like a design mistake. FWIW, C++ seems to do a sane thing. Class decls do not conflict and the assertion passes: int main(int argc, char *argv[]) { int *x1; int *x2; { class C { }; static int x; x1 = &x; } { class C { }; static int x; x2 = &x; } assert(x1 != x2); }

While yes I would agree that: { static int v = 1; } { static int v = 1; } Should be an error, and thus the PR should be merged. I don't agree that the reason this issue was created: foreach (T; TypeTuple!(int, double)) { static temp = T.stringof; } should be an error, sorry if I failed to explain myself well enough originally.

Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/0b575f80b644715207ff18ca92d7bfb4708186aa fix Issue 11720 - Function-local static variables should cause "already defined in another scope" error https://github.com/D-Programming-Language/dmd/commit/5901e163e48a5f13a5a1d970741229b3c2878e0d Merge pull request #2947 from 9rnsr/fix11720 Issue 11720 - Function-local static variables should cause "already defined in another scope" error

Mark as fixed? As for avoiding mangling issues, I think this is Issue 3031.

(In reply to Andrej Mitrovic from comment #9) > As for avoiding mangling issues, I think this is Issue 3031. Mark as a duplication of 3031. *** This issue has been marked as a duplicate of issue 3031 ***