llvm dev - Sep 2004 - [LLVMdev] struct and class under VC7.1

Hi all,

Finally I managed to find out a strange problem under Visual C

During the link of the HowToUseJIT program, I was always missing some 
symbols... and I was going crazy testing out different options...

At the end, unmangling the differences in what linker was searching and 
what was present in the libraries, I found that the problem is
that we have something like this...

Value.h
struct Value {
	bla bla bla
}

and around in the other files:
SlotCalculator.h
SchedGraph.h
<big snip>

class Value;

The linker complains about the different parameters types, and raise an 
unresolved external symbol.

I can resolve the iussue
a) turning the original struct Value { ... } in class Value { public: 
.... }
b) turning all the class Value; into struct Value;

The same is for TargetJITInfo, Type, IntrinsicLowering and others...

Suggestions?

---
Paolo Invernizzi

MSVC++ is picky about this.  It considers classes and structs to be
different types so you have to be consistent.  If you forward declared a
struct as a class within the same compilation unit, it would complain
about that too.  It's not just linking.

On Thu, 23 Sep 2004 15:59:42 +0200
Paolo Invernizzi <arathorn at fastwebnet.it> wrote:
> Hi all,
> 
> Finally I managed to find out a strange problem under Visual C
> 
> During the link of the HowToUseJIT program, I was always missing some 
> symbols... and I was going crazy testing out different options...
> 
> At the end, unmangling the differences in what linker was searching and 
> what was present in the libraries, I found that the problem is
> that we have something like this...
> 
> Value.h
> struct Value {
> 	bla bla bla
> }
> 
> and around in the other files:
> SlotCalculator.h
> SchedGraph.h
> <big snip>
> 
> class Value;
> 
> The linker complains about the different parameters types, and raise an 
> unresolved external symbol.
> 
> I can resolve the iussue
> a) turning the original struct Value { ... } in class Value { public: 
> .... }
> b) turning all the class Value; into struct Value;
> 
> The same is for TargetJITInfo, Type, IntrinsicLowering and others...
> 
> Suggestions?
> 
> ---
> Paolo Invernizzi
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev

On Sep 23, 2004, at 4:08 PM, Jeff Cohen wrote:
> MSVC++ is picky about this.  It considers classes and structs to be
> different types so you have to be consistent.  If you forward declared 
> a
> struct as a class within the same compilation unit, it would complain
> about that too.  It's not just linking.
You are right...

BTW, I've just fixed that problem in my checkout and, among others 
terrible hacks, here I am:

:\home\arathorn\sandbox\llvm>HowToUseJIT.exe
We just constructed this LLVM module:


implementation   ; Functions:

int %add1(int %AnArg) {
EntryBlock:
         %addresult = add int 1, %AnArg          ; <int> [#uses=1]
         ret int %addresult
}

int %foo() {
EntryBlock:
         %add1 = call int %add1( int 10 )                ; <int> 
[#uses=1]
         ret int %add1
}


Running foo: Result: 11

D:\home\arathorn\sandbox\llvm>

Yabba! Yabba! Yabba! ;-)

---
Paolo Invernizzi