[Issue 9598] New: Cannot use moveFront on MapResult!(lambda, ByLine!(char, char))

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=9598

           Summary: Cannot use moveFront on MapResult!(lambda,
                    ByLine!(char, char))
           Product: D
           Version: D2
          Platform: All
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: zshazz at gmail.com


--- Comment #0 from Chris Cain <zshazz at gmail.com> 2013-02-26 22:33:51 PST ---
Using DMD 2.062 with no command line arguments other than the source file in
question

I have the following (expected valid) code:

---

import std.stdio, std.file, std.algorithm, std.conv, std.range;

void main() {
    dirEntries("data", "*.out", SpanMode.shallow)
        .map!(e => File(e.name).byLine()
            .map!(line => text(line))() // compile error
        )()
        .array()
        .nWayUnion() // line 9
        .copy(stdout.lockingTextWriter);
}

---

Which produces errors. Error 1 is a compile-time failure producing the
following message:

---
C:\D\dmd2\windows\bin\..\..\src\phobos\std\range.d(6695): Error: static assert 
"Cannot move front of a range with a postblit and an rvalue front."
C:\D\dmd2\windows\bin\..\..\src\phobos\std\container.d(3797):       
instantiated from here: moveFront!(MapResult!(__lambda4, ByLine!(char,
char))[])
C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(10526):       
instantiated from here: BinaryHeap!(MapResult!(__lambda4, ByLine!(char,
char))[], compFront)
C:\D\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(10562):       
instantiated from here: NWayUnion!("a < b", MapResult!(__lambda4, ByLine!(char,
char))[])
D:\[snip]\src\reducedCase.d(9):        instantiated from here: nWayUnion!("a <
b", MapResult!(__lambda4, ByLine!(char, char))[])

---

If I change the code to this:

---

import std.stdio, std.file, std.algorithm, std.conv, std.range;

void main() {
    dirEntries("data", "*.out", SpanMode.shallow)
        .map!(e => File(e.name).byLine()
            .map!text() // Compiles, runtime error
        )()
        .array()
        .nWayUnion() // line 9
        .copy(stdout.lockingTextWriter);
}

---

Then the code compiles, but produces a runtime error (when files are in data
directory and named *.out):

object.Error: Access Violation
----------------
0x00429674
0x004294FF
0x7730B459 in LdrRemoveLoadAsDataTable
0x7730B42B in LdrRemoveLoadAsDataTable
0x772C0133 in KiUserExceptionDispatcher
0x0018F6E8
0x0018F738
----------------


Specifically, these errors apply to MapResult!(lambda, ByLine!(char, char)).
For instance, using a string[][] as an array and applying a .map!text() as
above, there is no problem for either case.

---

import std.stdio, std.file, std.algorithm, std.conv, std.range;

void main() {
    [["abc", "cbd"], ["dce", "efg"]]
        .map!(e =>
            //e.map!text()               // OK
            e.map!(line => text(line))() // OK
        )()
        .array()
        .nWayUnion()
        .copy(stdout.lockingTextWriter);
}

---

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