Bug 6081 – Function Literal Templates Don't Work when Nested in Templates

The following piece of code, which finds the length of the longest line in a file, pipe!(readText, splitlines, map!((a) { return a.length; }), reduce!max)("Temp.d"); fails with: Error: expression template map(Range) if (isInputRange!(Unqual!(Range))) is not a valid template value argument If you try to get around it by saying pipe!(readText, splitlines, map!(delegate size_t(string a) { return a.length; }), reduce!max)("Temp.d"); you then get: Error: delegate std.algorithm.__dgliteral1 cannot access frame of function Temp.main.__dgliteral1 and saying "function" instead of "delegate" doesn't change anything. You can get around it with using a string instead of a function literal as the template argument, but that still doesn't really solve the issue.

Well, sorry: if you say "function" instead of "delegate", the error _does_ change... it becomes: Error: delegate std.algorithm.__dgliteral1 cannot access frame of function Temp.main.__dgliteral1

(In reply to comment #1) > Well, sorry: if you say "function" instead of "delegate", the error _does_ > change... it becomes: > > Error: delegate std.algorithm.__dgliteral1 cannot access frame of function > Temp.main.__dgliteral1 Whoops, major apologies for the typo and 2nd comment... should've been: Error: function std.algorithm.__funcliteral1 cannot access frame of function Temp.main.__funcliteral1

It would be helpful if code snippets include full compilable code. Anyway, based on the bug description, I constructed the following test case: ---- import std.algorithm, std.file, std.functional, std.string; void main() { pipe!(readText, splitLines, map!((a) { return a.length; }), reduce!max)("Temp.d"); } ---- This code compiles correctly in dmd git HEAD (6a90c4df), so it appears that it has been fixed. Please reopen this bug if you still encounter problems. Thanks!