Bug 15874 – getSymbolsByUDA fails if struct has no UDAs

I think, this specific case should work, but it does not. struct Test { int x; } struct UDA { } unittest { import std.traits; static assert(getSymbolsByUDA!(Test,UDA).length == 0); } This fails with: /usr/include/dlang/dmd/std/traits.d(6721): Error: array index [0] is outside array bounds [0 .. 0] /usr/include/dlang/dmd/std/traits.d(6726): Error: template instance std.traits.getSymbolsByUDA!(Test, UDA).toSymbols!() error instantiating The issue is that toSymbols within getSymbolsByUDA does not handles case with 0 matches. I think simple change to something like this should work: template toSymbols(names...) { static if (names.length == 0) toSymbols = AliasSeq!(); else mixin("alias toSymbols = AliasSeq!(symbol.%s, toSymbols!(names[1..$]));" .format(names[0])); }

Created pull request: https://github.com/D-Programming-Language/phobos/pull/4164 This is first time I'm contributing to github and D, if I'm doing something wrong, please tell me :)

Commit pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/cf4f09f12edbf3339c2e8d69e6b4d0e7fd2d660c Merge pull request #4164 from Ukalnins/issue_15874 Fix Issue 15874 - getSymbolsByUDA fails if struct has no UDAs