[cfe-dev] [llvm-dev] DeclarationName and the StringRef.

[Friedman, Eli via cfe-dev]

On 1/4/2017 3:07 AM, Umesh Kalappa wrote:
> Hi Eli and All ,
>
> We added the support to rename the function name ,i.e something like 
> "func" to "test_func" for any function we append the string 
> "test_",hence modified the code @ @ lib/Sema/SemaDecl.cpp like
>
>  static FunctionDecl* CreateNewFunctionDecl(Sema &SemaRef, Declarator &D,
>                                            DeclContext *DC, QualType &R,
>                                            TypeSourceInfo *TInfo,
>                                            StorageClass SC,
>                                            bool &IsVirtualOkay){
>  DeclarationNameInfo NameInfo = SemaRef.GetNameForDeclarator(D);
>  DeclarationName Name = NameInfo.getName();
>  std::string ExtPreRef;
>   SmallString<32> Str;
>   StringRef EP = ("Test_" + Name.getAsString()).toStringRef(Str);
>   const IdentifierInfo &test = SemaRef.PP.getIdentifierTable().get(EP);
>   DeclarationName ExternName(&test);
>    SemaRef.ExternPrefixMap[Name.getAsString()] = ExternName;
>   NameInfo.setName(ExternName);
>
>  FunctionDecl *NewFD = nullptr;
>  bool isInline = D.getDeclSpec().isInlineSpecified();
>
> }
>
> testcase.c
>
> int foo();
> int bar();
>
>
> int bar()
> {
>  return 1;
> }
>
>
> int foo()
> {
>         return foo() + bar();
> }
>
> int (*ptr) ();
>
> int main()
> {
>         ptr =  bar;
>         return ptr();
> }
>
>
> we we try to compile the source testcase.c ,we ended up with the below 
> warnings and error.
>
> test.c:12:9: warning: implicit declaration of function 'foo' is 
> invalid in C99 [-Wimplicit-function-declaration]
>         return foo() + bar();
>                ^
> DefinefooFound:foo
> test.c:12:17: warning: implicit declaration of function 'bar' is 
> invalid in C99 [-Wimplicit-function-declaration]
>         return foo() + bar();
>                        ^
> DefinebarFound:bar
> DefinemainCome
> maintest.c:19:6: error: assigning to 'int (*)()' from incompatible 
> type '<overloaded function type>'
>         ptr = Test_list_bar;
>             ^ ~~~~~~~~~~~~~
> test.c:12:17: note: candidate function
>         return foo() + bar();

Hang on, lets take a step back at this point.  Why are you doing this?  
If you don't want the function to have a different name, don't rename it.

If you need to change the name of a function in the generated 
IR/assembly without changing the semantic name, you can use the __asm__ 
attribute (as in `int f() __asm__("test_f");`).

-Eli

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