This is with the linux (openSUSE) DMD64 v2.059. Here is the code of interest. ---------- import std.stdio; void println(int i) { writeln(i); } // Bug trigger #1 void main() { // methods of Exception auto b = [ __traits(allMembers, Exception) ]; writeln(b); // Bug trigger #2 asdf; // Bug trigger #3 (intentional compilation error) } ---------- If Bug trigger #3 is commented, then it compiles without output (as expected) with ---------- $ dmd unexpected_error_messages.d ---------- If I comment out EITHER Bug trigger #1 or #2 then I receive the expected compilation error ---------- unexpected_error_messages.d(12): Error: undefined identifier asdf ---------- If the code is compiled as-is, then I get this confusing mess of errors, the latter of which seems completely irrelevant in this context. This might be triggered by a bug. ---------- unexpected_error_messages.d(12): Error: undefined identifier asdf /usr/include/d/dmd/phobos/std/conv.d(244): Error: template std.conv.toImpl does not match any function template declaration /usr/include/d/dmd/phobos/std/conv.d(244): Error: template std.conv.toImpl cannot deduce template function from argument types !(string)(ubyte) /usr/include/d/dmd/phobos/std/conv.d(244): Error: template instance toImpl!(string) errors instantiating template /usr/include/d/dmd/phobos/std/conv.d(3034): Error: template instance std.conv.to!(string).to!(ubyte) error instantiating /usr/include/d/dmd/phobos/std/conv.d(3016): instantiated from here: textImpl!(string,string,void*,string,int,string,int,string,char,string,ubyte,string,ubyte,string,bool,string,bool,string,bool,string,bool,string,bool,string,const(char)[],string,const(char)[],string) /usr/include/d/dmd/phobos/std/format.d(1078): instantiated from here: text!(string,void*,string,int,string,int,string,char,string,ubyte,string,ubyte,string,bool,string,bool,string,bool,string,bool,string,bool,string,const(char)[],string,const(char)[],string) /usr/include/d/dmd/phobos/std/format.d(392): instantiated from here: FormatSpec!(char) /usr/include/d/dmd/phobos/std/stdio.d(687): ... (1 instantiations, -v to show) ... /usr/include/d/dmd/phobos/std/stdio.d(1574): instantiated from here: write!(string[],char) unexpected_error_messages.d(10): instantiated from here: writeln!(string[]) /usr/include/d/dmd/phobos/std/conv.d(3016): Error: template instance std.conv.textImpl!(string,string,void*,string,int,string,int,string,char,string,ubyte,string,ubyte,string,bool,string,bool,string,bool,string,bool,string,bool,string,const(char)[],string,const(char)[],string) error instantiating /usr/include/d/dmd/phobos/std/format.d(1078): instantiated from here: text!(string,void*,string,int,string,int,string,char,string,ubyte,string,ubyte,string,bool,string,bool,string,bool,string,bool,string,bool,string,const(char)[],string,const(char)[],string) /usr/include/d/dmd/phobos/std/format.d(392): instantiated from here: FormatSpec!(char) /usr/include/d/dmd/phobos/std/stdio.d(687): instantiated from here: formattedWrite!(LockingTextWriter,char,string[]) /usr/include/d/dmd/phobos/std/stdio.d(1574): instantiated from here: write!(string[],char) unexpected_error_messages.d(10): instantiated from here: writeln!(string[]) /usr/include/d/dmd/phobos/std/format.d(1078): Error: template instance std.conv.text!(string,void*,string,int,string,int,string,char,string,ubyte,string,ubyte,string,bool,string,bool,string,bool,string,bool,string,bool,string,const(char)[],string,const(char)[],string) error instantiating /usr/include/d/dmd/phobos/std/format.d(392): instantiated from here: FormatSpec!(char) /usr/include/d/dmd/phobos/std/stdio.d(687): instantiated from here: formattedWrite!(LockingTextWriter,char,string[]) /usr/include/d/dmd/phobos/std/stdio.d(1574): instantiated from here: write!(string[],char) unexpected_error_messages.d(10): instantiated from here: writeln!(string[]) ----------