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Home » U++ TheIDE » U++ TheIDE: Compiling, Linking, Debugging of your packages » Strange build error only after changing
| Strange build error only after changing [message #13812] |
Tue, 29 January 2008 00:32  |
cbpporter
Messages: 1401
Registered: September 2007
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Ultimate Contributor |
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Hi!
I found a really strange build error. I have some sources on the net. I download them, compile, link, everything is OK. I add an inline function to the main .h, still compiles. I use it in one of the .cpp files, and I get:
ToolsDropPane.obj : error LNK2005: "public: static class Upp::Iml & __cdecl CBPImages::Iml(void)" (?Iml@CBPIm
ages@@SAAAV0Upp@@XZ) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static class Upp::Image __cdecl CBPImages::Get(int)" (?Get@CBPIma
ges@@SA?AVImage@Upp@@H@Z) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static class Upp::Image __cdecl CBPImages::Get(char const *)" (?G
et@CBPImages@@SA?AVImage@Upp@@PBD@Z) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static int __cdecl CBPImages::Find(class Upp::String const &)" (?
Find@CBPImages@@SAHABVString@Upp@@@Z) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static int __cdecl CBPImages::Find(char const *)" (?Find@CBPImage
s@@SAHPBD@Z) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static void __cdecl CBPImages::Set(int,class Upp::Image const &)"
(?Set@CBPImages@@SAXHABVImage@Upp@@@Z) already defined in $blitz.obj
ToolsDropPane.obj : error LNK2005: "public: static void __cdecl CBPImages::Set(char const *,class Upp::Image
const &)" (?Set@CBPImages@@SAXPBDABVImage@Upp@@@Z) already defined in $blitz.obj
D:\Develop\upp12\out\MSC8.Debug_full.Gui\CBPMain.exe : fatal error LNK1169: one or more multiply defined symb
ols found
Even after pressing undo to remove all changes, these errors persist. Rebuild, clean + rebuild, nothing helps. I've even done a treedif to see, and the files are absolutely identical to their downloaded state. Only happens with MSC8.
I can't post a test case, but do you have any idea how to fix this?
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| Re: Strange build error only after changing [message #13818 is a reply to message #13812] |
Tue, 29 January 2008 09:50  |
mr_ped
Messages: 825
Registered: November 2005
Location: Czech Republic - Praha
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Experienced Contributor |
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Try to switch off blitz and/or "Build / Clean UPPOUT".
Depends which one you value more, the already built objects or usage of BLITZ. (I suggest to do both)
How did you do "clean", trough Upp build menu? Maybe some blitz files remain anyway so Clean UPPOUT is safer option (that deletes absolutely everything from build directory).
To me it looks like some .cpp file is compiled both individually and inside the big "blitz" file, so all of it's instantiated variables do get multiple definitions during linking.
It may be also problem with instantiating variables inside .h/.hpp files.
And finally I would check date/time of all source files, and current time on the machine, if they are bogus (future?) dates, it may cause havoc both to compiler itself and to blitz heuristic (at least so I think).
edit: And on multi-core CPU the multi threaded compilation may hit the problem with future dates too, there was some fix already between 2007.1 and current dev I think? Try to limit compilation to single thread (Setup/Environment/IDE/HYDRA 1 threads), if this helps, check the "changes" forum if you are using older UPP to see when there was some minor fix introduced.
(But I don't think this is the cause, as this one always did work when the compilation was invoked second time after first failure.)
[Updated on: Tue, 29 January 2008 09:54] Report message to a moderator |
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| Re: Strange build error only after changing [message #13824 is a reply to message #13821] |
Tue, 29 January 2008 13:04 |
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mirek
Messages: 13975
Registered: November 2005
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Ultimate Member |
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| cbpporter wrote on Tue, 29 January 2008 04:42 |
I tried everything that you suggested. Set all dates for today, done repeated cleans (normal + UPPOUT) followed by builds, with and without BLITZ, with different values to HYDRA heads, and still no luck. Tested on 2008.1beta and 7.12dev and reproduced on another computer.
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IMO, you have wrong #includes for .iml.
You should include iml_header.h in header file and iml_source.h in .cpp.
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How do you usually set up a complex project structure, with interface split into multiple files/classes, so that it optimally uses BLITZ?
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For BLITZ, the best is single header per package included in all .cpp files.
Mirek
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| Re: Strange build error only after changing [message #13833 is a reply to message #13824] |
Tue, 29 January 2008 14:35 |
cbpporter
Messages: 1401
Registered: September 2007
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Ultimate Contributor |
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| luzr wrote on Tue, 29 January 2008 14:04 |
IMO, you have wrong #includes for .iml.
You should include iml_header.h in header file and iml_source.h in .cpp.
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Thank you!
That solved the problem. I even created a separate .cpp only for <Draw/iml_sources.h>. Since when do you need to include separate files int the .h and .cpp? I never had any problems with just using <Draw/iml.h> since I started using U++.
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For BLITZ, the best is single header per package included in all .cpp files.
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I think it's quite ironic that in order to increase your compilation speed you need to do the exact opposite of what you learned about C++: if you minimize you .h dependencies, you compilation speed could improve.
Just a question: is BLITZ partially responsible for the big binary size? It would seem that it makes it rather difficult to generate small obj files.
[Updated on: Tue, 29 January 2008 14:56] Report message to a moderator |
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| Re: Strange build error only after changing [message #13838 is a reply to message #13833] |
Tue, 29 January 2008 16:11 |
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mirek
Messages: 13975
Registered: November 2005
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Ultimate Member |
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| cbpporter wrote on Tue, 29 January 2008 08:35 |
| luzr wrote on Tue, 29 January 2008 14:04 |
IMO, you have wrong #includes for .iml.
You should include iml_header.h in header file and iml_source.h in .cpp.
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Thank you!
That solved the problem. I even created a separate .cpp only for <Draw/iml_sources.h>. Since when do you need to include separate files int the .h and .cpp? I never had any problems with just using <Draw/iml.h> since I started using U++.
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iml.h is just doing both _header and _source. So you can really use it for a single .cpp file and better put it into .cpp...
Think about _header as variable declaration ("extern") and _source as definition.
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I think it's quite ironic that in order to increase your compilation speed you need to do the exact opposite of what you learned about C++: if you minimize you .h dependencies, you compilation speed could improve.
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Actually, it really does not matter that much.... (BLITZ will work with "sparse headers" model quite will too). But it is the most straightforward way.
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Just a question: is BLITZ partially responsible for the big binary size? It would seem that it makes it rather difficult to generate small obj files.
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Yes. That is why for release mode, BLITZ is not recommended.
Actually, I have started to consider inverse-BLITZ technique for release mode - one that would split .cpp files by functions 
(In theory, this should work with GCC and Linux with -ffunction-sections. In practice, it does not).
Mirek
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