Bug 14769 – Cannot instantiate templates for locally defined struct when constructor is present

The following fails to compile, with the error "Error: template std.conv.toImpl cannot deduce function from argument types !(S2)(string)" (i.e. S1 works fine, but S2 doesn't): ----- import std.conv; unittest { struct S1 { public string a; } struct S2 { public string a; this(string s) { a = s; } } S1 s1 = to!S1(""); S2 s2 = to!S2(""); // <- ERROR } ----- Moving the struct definitions out of the unittest block also works fine: ----- import std.conv; struct S1 { public string a; } struct S2 { public string a; this(string s) { a = s; } } unittest { S1 s1 = to!S1(""); S2 s2 = to!S2(""); } ----- This is using DMD v2.067.

(In reply to Simon Sigurdhsson from comment #0) > The following fails to compile, with the error "Error: template > std.conv.toImpl cannot deduce function from argument types !(S2)(string)" > (i.e. S1 works fine, but S2 doesn't): S2 is a nested struct and you can create the instance only inside the enclosing unittest, because it requires valid context. Therefore, to!S2 function cannot create it. > Moving the struct definitions out of the unittest block also works fine: Moving declarations out of the unittest will make S2 non-nested. Then the limitation will be lifted. A quick workaround is adding `static` to struct S2.

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