[cfe-commits] r43023 - in /cfe/trunk: Sema/SemaDecl.cpp Sema/SemaExpr.cpp clang.xcodeproj/project.pbxproj

[Steve Naroff]

On Oct 17, 2007, at 5:37 PM, Chris Lattner wrote:

>> Bad cast...need to use dyn_cast_or_null. Also changed  
>> Sema::InitBuiltinVaListType (which had the same bug).
>
> Hi Steve,
>
> Why are these dyn_cast_or_null?  It seems like none of those cases  
> allow null pointers?
>

The second case you forwarded currently needs it (you may be right  
about the first).

If I don't use dyn_cast_or_null(), the following case will bus error.  
With dyn_cast_or_null(), we assert (missing '@interface  
NSConstantString').

[dylan:~/llvm/tools/clang] admin% cat trivial.m

@class NSString;

NSString *s = @"123";

This is because NSConstantString isn't really built-in - we rely on  
seeing NSString.h to get the @interface for NSConstantString. This  
dividing line between the language and library/platform is a little  
murky (unfortunately, given the adhoc language evolution:-).

So...until we have a better solution for how to integrate  
NSConstantString, I have the conservative dyn_cast_or_null. In  
practice (with MacOS X/Cocoa), this isn't a problem. It's unlikely  
developers will bump into this assert.

snaroff

> -Chris
>
>>
>> Modified:
>>     cfe/trunk/Sema/SemaDecl.cpp
>>     cfe/trunk/Sema/SemaExpr.cpp
>>     cfe/trunk/clang.xcodeproj/project.pbxproj
>>
>> Modified: cfe/trunk/Sema/SemaDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/Sema/ 
>> SemaDecl.cpp?rev=43023&r1=43022&r2=43023&view=diff
>>
>> ===================================================================== 
>> =========
>> --- cfe/trunk/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/Sema/SemaDecl.cpp Mon Oct 15 19:00:18 2007
>> @@ -154,7 +154,7 @@
>>    IdentifierInfo *VaIdent = &Context.Idents.get 
>> ("__builtin_va_list");
>>    ScopedDecl *VaDecl = LookupScopedDecl(VaIdent,  
>> Decl::IDNS_Ordinary,
>>                                            SourceLocation(),  
>> TUScope);
>> -  TypedefDecl *VaTypedef = cast<TypedefDecl>(VaDecl);
>> +  TypedefDecl *VaTypedef = dyn_cast_or_null<TypedefDecl>(VaDecl);
>>    Context.setBuiltinVaListType(Context.getTypedefType(VaTypedef));
>>  }
>>
>>
>> Modified: cfe/trunk/Sema/SemaExpr.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/Sema/ 
>> SemaExpr.cpp?rev=43023&r1=43022&r2=43023&view=diff
>>
>> ===================================================================== 
>> =========
>> --- cfe/trunk/Sema/SemaExpr.cpp (original)
>> +++ cfe/trunk/Sema/SemaExpr.cpp Mon Oct 15 19:00:18 2007
>> @@ -1896,9 +1896,9 @@
>>      IdentifierInfo *NSIdent = &Context.Idents.get 
>> ("NSConstantString");
>>      ScopedDecl *IFace = LookupScopedDecl(NSIdent,  
>> Decl::IDNS_Ordinary,
>>                                           SourceLocation(), TUScope);
>> -    ObjcInterfaceDecl *stringInterface = cast<ObjcInterfaceDecl> 
>> (IFace);
>> -    assert(stringInterface && "missing '@interface  
>> NSConstantString'");
>> -    Context.setObjcConstantStringInterface(stringInterface);
>> +    ObjcInterfaceDecl *strIFace =  
>> dyn_cast_or_null<ObjcInterfaceDecl>(IFace);
>> +    assert(strIFace && "missing '@interface NSConstantString'");
>> +    Context.setObjcConstantStringInterface(strIFace);
>>    }
>>    QualType t = Context.getObjcConstantStringInterface();
>>    t = Context.getPointerType(t);
>>
>> Modified: cfe/trunk/clang.xcodeproj/project.pbxproj
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/clang.xcodeproj/ 
>> project.pbxproj?rev=43023&r1=43022&r2=43023&view=diff
>>
>> ===================================================================== 
>> =========
>> --- cfe/trunk/clang.xcodeproj/project.pbxproj (original)
>> +++ cfe/trunk/clang.xcodeproj/project.pbxproj Mon Oct 15 19:00:18  
>> 2007
>> @@ -742,7 +742,6 @@
>>  		08FB7793FE84155DC02AAC07 /* Project object */ = {
>>  			isa = PBXProject;
>>  			buildConfigurationList = 1DEB923508733DC60010E9CD /* Build  
>> configuration list for PBXProject "clang" */;
>> -			compatibilityVersion = "Xcode 2.4";
>>  			hasScannedForEncodings = 1;
>>  			mainGroup = 08FB7794FE84155DC02AAC07 /* clang */;
>>  			projectDirPath = "";
>>
>>
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>

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