[Issue 15324] symbol is already defined

Nov 13, 2015

Johannes Pfau

Nov 13, 2015

Johannes Pfau

Nov 13, 2015

Johannes Pfau

November 13, 2015

[Issue 15324] symbol is already defined

Posted by Johannes Pfau

Permalink

Johannes Pfau

Permalink

https://issues.dlang.org/show_bug.cgi?id=15324

Johannes Pfau <johannespfau@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |johannespfau@gmail.com

--- Comment #1 from Johannes Pfau <johannespfau@gmail.com> ---
Created attachment 1567
  --> https://issues.dlang.org/attachment.cgi?id=1567&action=edit
reduced test case

I've added a dustmite reduced test case. Compile like this:

dmd main.d
/usr/bin/ld: Warning: size of symbol
`_D4main179__T19MultiIndexContainerTC4core6thread6ThreadTS4main113__T9IndexedByS964main89__T6HashedVbi0VAyaa1_61VAyaa21_7479706569642861292e6765744861736828266129VAyaa4_613d3d62ZZ9IndexedByZ19MultiIndexContainer9__mixin108containsMxFC4core6thread6ThreadZb'
changed from 111 in main.o to 103 in main.o

gdc main.d
/tmp/cczTwcpO.s: Assembler messages:
/tmp/cczTwcpO.s:195: Error: symbol
`_D4main179__T19MultiIndexContainerTC4core6thread6ThreadTS4main113__T9IndexedByS964main89__T6HashedVbi0VAyaa1_61VAyaa21_7479706569642861292e6765744861736828266129VAyaa4_613d3d62ZZ9IndexedByZ19MultiIndexContainer9__mixin108containsMxFC4core6thread6ThreadZb'
is already defined



It seems scary that the size of the symbol changes. But maybe the bigger issue is that the template is actually emitted twice to the same object file. This seems to be tolerated by ld (dmd only gets a warning) but not by the assembler (gdc outputs asm and calls the assembler which refuses to assemble this).

Pinging Iain as I'm not sure if the assembler only complains because the size differs or whether it will still complain even if the size difference is fixed.

--

https://issues.dlang.org/show_bug.cgi?id=15324 --- Comment #2 from Johannes Pfau <johannespfau@gmail.com> --- Raised importance to critical as this prevents some of the bigger D projects from sucessfully compiling with GDC (pyd, wxD). --

https://issues.dlang.org/show_bug.cgi?id=15324 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ibuclaw@gdcproject.org --- Comment #3 from Iain Buclaw <ibuclaw@gdcproject.org> --- (In reply to Johannes Pfau from comment #1) > Pinging Iain as I'm not sure if the assembler only complains because the size differs or whether it will still complain even if the size difference is fixed. My understanding is that GAS will complain and error for *any* duplicate symbol, regardless of what flags are associated with it, or size it has. --

https://issues.dlang.org/show_bug.cgi?id=15324 Vincent R <v.richomme@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |v.richomme@gmail.com --- Comment #4 from Vincent R <v.richomme@gmail.com> --- Any progress ?? --

https://issues.dlang.org/show_bug.cgi?id=15324 --- Comment #5 from Iain Buclaw <ibuclaw@gdcproject.org> --- I don't think it's a compiler bug, but it would help indefinitely if only the compiler semantic passes checked for conflicting function overrides upon declaration, rather than when they are called. I can distil test case down to: --- struct MultiIndexContainer() { bool contains(int k) const { auto r = true; return r; } bool contains(int k) const { return false; } } void main() { MultiIndexContainer!() m; } --- If these were not templates, you'd get multiple definition errors. But as that is not the case, these instead get put on comdat and merged. This as you've discovered gives you an entirely different kind of linker error, but it's simply a different side of the same coin. The real bug is in the program logic. Somehow, you have done the following (abridged) --- alias Value ValueView; alias typeof(Value.init) KeyType; bool contains(ValueView value) const { ... } bool contains(KeyType k) const { ... } --- You should add a constraint to ensure that ValueView != KeyType, or rename the methods so as they don't conflict, such as containsValue() and containsKey(). --

https://issues.dlang.org/show_bug.cgi?id=15324 --- Comment #6 from Ellery Newcomer <ellery-newcomer@utulsa.edu> --- this prevents pyd from compiling under gdc: https://github.com/ariovistus/pyd/issues/42 --

https://issues.dlang.org/show_bug.cgi?id=15324 Johannes Pfau <johannespfau@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|critical |normal --- Comment #7 from Johannes Pfau <johannespfau@gmail.com> --- Reducing importance: As explained by Iain, the reported example is invalid D code. DMD should still warn about this. Additionally, there are cases where DMD passes template symbols multiple times to the backend. I don't have a test case right now, but we added a workaround for this to GDC and GDC will now compile such code. So this is no longer a blocker for GDC. --

https://issues.dlang.org/show_bug.cgi?id=15324 Walter Bright <bugzilla@digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- See Also| |https://issues.dlang.org/sh | |ow_bug.cgi?id=17332 --

Forums