[Issue 17547] New: Compile-time map!(...) fails to compile inside a struct when using lambdas ("this.__lambda1 has no value")

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17547

          Issue ID: 17547
           Summary: Compile-time map!(...) fails to compile inside a
                    struct when using lambdas ("this.__lambda1 has no
                    value")
           Product: D
           Version: D2
          Hardware: x86
                OS: Windows
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: alex.bleron at gmail.com

The following code fails to compile:

////////////////////////////////////////
// https://dpaste.dzfl.pl/2573f6fb2ff5
import std.algorithm : map;
import std.array : join;
struct Test 
{
  pragma(msg, ["a", "b", "c", "d"].map!(a => a).join("\n"));
}

////////////////////////////////////////
Compiler output:
src/phobos/std/algorithm/iteration.d(455): Error: this.__lambda1 has no value
6 : Error: CTFE failed because of previous errors in map
6 : called from here: join(map(["a", "b", "c", "d"]), "\x0a")
6 : while evaluating pragma(msg, join(map(["a", "b", "c", "d"]), "\x0a"))
Compilation failed

////////////////////////////////////////
Expected compiler output:
a
b
c
d

-------------------------------------------------------

This code also fails (replacing the lambda with a function literal):

////////////////////////////////////////
import std.algorithm : map;
import std.array : join;
struct Test 
{
  // std/algorithm/iteration.d(455): Error: this.__funcliteral1 has no value
  pragma(msg, ["a", "b", "c", "d"].map!(function (a) { return a;
}).join("\n"));
}


-------------------------------------------------------


However, this works:

////////////////////////////////////////
import std.algorithm : map;
import std.array : join;
struct Test 
{
  pragma(msg, ["a", "b", "c", "d"].map!("a").join("\n"));
}


-------------------------------------------------------

And this works too:

////////////////////////////////////////
import std.algorithm : map;
import std.array : join;
struct Test 
{
  pragma(msg, ["a", "b", "c", "d"].map!(function string(string a) { return a;
}).join("\n"));
}

--