https://issues.dlang.org/show_bug.cgi?id=15974

          Issue ID: 15974
           Summary: Spurious error: argument to mixin must be a string,
                    not (expression()) of type string
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: trivial
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: iamthewilsonator@hotmail.com

DMD64 D Compiler v2.070-devel-5123284

alias allDeviceFns = AliasSeq!("vkCreateSampler");

void loadDeviceFns(VkDevice d)
{
    enum allFns = [allDeviceFns];
    foreach(f;allFns)
    {
        mixin("%s =
cast(typeof(%s)vkGetDeviceProcAddr(d,toStringz(\"%s\"))".format(f,f,f));
    }
 }
Gives two errors:
    vk.d(1576): Error: variable f cannot be read at compile time
vk.d(1576):        called from here: format("%s =
cast(typeof(%s)vkGetDeviceProcAddr(d,toStringz(\"%s\"))", f, f, f)
    vk.d(1576): Error: argument to mixin must be a string, not (format("%s =
cast(typeof(%s)vkGetDeviceProcAddr(d,toStringz(\"%s\"))", f, f, f)) of type
string

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