[Issue 20802] [REG2.088.0] Link failure with writefln

May 06, 2020

Tim

Jan 10, 2023

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elpenguino+D@gmail.com

https://issues.dlang.org/show_bug.cgi?id=20802 Tim <tim.dlang@t-online.de> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |link-failure --

https://issues.dlang.org/show_bug.cgi?id=20802 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ibuclaw@gdcproject.org --- Comment #1 from Iain Buclaw <ibuclaw@gdcproject.org> --- Now: --- issue20802.o: in function `_D4core8internal7switch___T14__switch_errorZQrFNaNbNiNfAyamZv': issue20802.d:(.text._D4core8internal7switch___T14__switch_errorZQrFNaNbNiNfAyamZv[_D4core8internal7switch___T14__switch_errorZQrFNaNbNiNfAyamZv]+0x19): undefined reference to `_D4core9exception__T15__switch_errorTZQsFNaNbNiNeAyamZv' collect2: error: ld returned 1 exit status Error: linker exited with status 1 --

https://issues.dlang.org/show_bug.cgi?id=20802 Richard Cattermole <alphaglosined@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |alphaglosined@gmail.com --- Comment #2 from Richard Cattermole <alphaglosined@gmail.com> --- Another more slimmed down version that was experienced by someone on the N.G. ```d import std.uni, std.stdio; void main() { auto c1 = CodepointSet('a','z'+1); writefln("%s", c1); } ``` ``` /dlang/dmd/linux/bin64/../../src/druntime/import/core/internal/switch_.d:189: error: undefined reference to '_D4core9exception__T15__switch_errorTZQsFNaNbNiNeAyamZv' ``` https://forum.dlang.org/post/nvjgpznfizkishhubcuz@forum.dlang.org --

https://issues.dlang.org/show_bug.cgi?id=20802 Carl Sturtivant <sturtivant@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |sturtivant@gmail.com --

February 11

[Issue 20802] [REG2.088.0] Link failure with writefln

Posted by Spoov

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Spoov

Permalink

https://issues.dlang.org/show_bug.cgi?id=20802

Spoov <spoov0.707@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |spoov0.707@gmail.com

--- Comment #3 from Spoov <spoov0.707@gmail.com> ---
The example can be simplified a bit, same error as in previous comment:

############ test.d ##############
import std.uni;
void main()
{
     CodepointSet('a', 'z');
     dstring s;
     decodeGrapheme(s);
}
##################################

Reducing std.uni yields the code below, same error as above:

#### phobos/std/uni/package.d ####
module std.uni;

enum TransformRes { goOn }

void writeAligned()()
{
    final switch (TransformRes.goOn) { case TransformRes.goOn: break; }
}

struct GcPolicy {}
alias CodepointSet = InversionList!GcPolicy;
struct InversionList(SP=GcPolicy)
{
    this()(uint[] intervals...)
    {
        sanitize();
    }

    void sanitize()
    {
        throw new Exception("");
        writeAligned();
    }
}

void decodeGrapheme(Input)(ref Input inp)
{
    final switch (TransformRes.goOn) { case TransformRes.goOn: break; }
}
##################################

A final switch generates a call to core.internal.switch_.__switch_error for
handling the default case.
core.internal.switch_.__switch_error calls core.exception.__switch_errorT.
Both functions are templates.

By default a D program links with libphobos2.a.
libphobos2.a contains sanitize and writeAligned but not __switch_error and
__switch_errorT.
This is because libphobos2.a gets build in release mode which causes the call
to __switch_error to be replaced with a ud2 instruction.

The linker error shows that __switch_error is present but __switch_errorT is missing.

In the compiler is this code
https://github.com/dlang/dmd/blob/8ab0636400d890a777889b3c84b09bcaa119fd57/compiler/src/dmd/dsymbolsem.d#L4666
which handles the case where a template that got instantiated from a non-root
module,
gets instantiated from a root module.
The code fixes the template instantiation, but misses the template
instantiations that are caused by it.
Because of this __switch_errorT is not emitted to the object file.

The following three files form a minimal example that reproduces the issue:

############# a.d ################
import b;
extern(C) void main() => bar!true;

############# b.d ################
void missing()() {}
void foo()() => missing();
void bar(bool b)() { version (Release) {} else foo(); }
enum fptr = &bar!false;

########## object.d ##############
// empty to make debugging simpler

$ dmd -c -version=Release b.d
$ dmd a.d b.o
a.o: In function `_D1b__T3fooZQfFNaNbNiNfZv':
a.d:(.text._D1b__T3fooZQfFNaNbNiNfZv[_D1b__T3fooZQfFNaNbNiNfZv]+0x5): undefined
reference to `_D1b__T7missingZQjFNaNbNiNfZv'
collect2: error: ld returned 1 exit status
Error: linker exited with status 1

--

https://issues.dlang.org/show_bug.cgi?id=20802 Dlang Bot <dlang-bot@dlang.rocks> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |pull --- Comment #4 from Dlang Bot <dlang-bot@dlang.rocks> --- @tim-dlang created dlang/dmd pull request #16200 "Fix Bugzilla 20802 - Link failure with writefln" fixing this issue: - Fix Bugzilla 20802 - Link failure with writefln The issue is caused by compiling druntime/phobos and the application with different flags. The template instance for __switch_errorT is not included in the build of druntime/phobos, because they are compiled with -release. DMD will also not include it in an application compiled without -release, because it assumes, that it is already in druntime. See comment https://issues.dlang.org/show_bug.cgi?id=20802#c3 by Spoov. As a workaround the template instance for __switch_errorT is now always instantiated in druntime. https://github.com/dlang/dmd/pull/16200 --

https://issues.dlang.org/show_bug.cgi?id=20802 Dlang Bot <dlang-bot@dlang.rocks> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #5 from Dlang Bot <dlang-bot@dlang.rocks> --- dlang/dmd pull request #16200 "Fix Bugzilla 20802 - Link failure with writefln" was merged into stable: - f4ee5234bccf21a4d2b5ca6d3962ccc3dd7a7d06 by Tim Schendekehl: Fix Bugzilla 20802 - Link failure with writefln The issue is caused by compiling druntime/phobos and the application with different flags. The template instance for __switch_errorT is not included in the build of druntime/phobos, because they are compiled with -release. DMD will also not include it in an application compiled without -release, because it assumes, that it is already in druntime. See comment https://issues.dlang.org/show_bug.cgi?id=20802#c3 by Spoov. The template instance for __switch_errorT is now always instantiated in druntime, so it is part of the ABI of druntime. https://github.com/dlang/dmd/pull/16200 --

https://issues.dlang.org/show_bug.cgi?id=20802 --- Comment #6 from anonymous4 <dfj1esp02@sneakemail.com> --- This looks like a rather fundamental collision between speculative instantiation and conditional compilation. __switch_errorT can't be in druntime unconditionally because its behavior changes depending on compilation options. --

https://issues.dlang.org/show_bug.cgi?id=20802 --- Comment #7 from Iain Buclaw <ibuclaw@gdcproject.org> --- (In reply to anonymous4 from comment #6) > This looks like a rather fundamental collision between speculative instantiation and conditional compilation. __switch_errorT can't be in druntime unconditionally because its behavior changes depending on compilation options. Because it's a weak symbol, any local instantiation would override the unconditional instantiation in druntime. --

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