r257947 - Avoid self-assignment of SmallString, trigger UB behavior down the road.

[Benjamin Kramer via cfe-commits]

On Fri, Jan 15, 2016 at 11:52 PM, David Blaikie via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
>
>
> On Fri, Jan 15, 2016 at 2:29 PM, Joerg Sonnenberger via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
>>
>> Author: joerg
>> Date: Fri Jan 15 16:29:34 2016
>> New Revision: 257947
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=257947&view=rev
>> Log:
>> Avoid self-assignment of SmallString, trigger UB behavior down the road.
>
>
> Shouldn't we be fixing that in SmallString? (self /move/ assignment arguably
> can be UB, but self copy assign probably shouldn't be)

It's a partial self-copy via StringRef. I don't think guarding against
that very special case is worth it.

>>
>>
>> Modified:
>>     cfe/trunk/tools/driver/driver.cpp
>>
>> Modified: cfe/trunk/tools/driver/driver.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/tools/driver/driver.cpp?rev=257947&r1=257946&r2=257947&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/tools/driver/driver.cpp (original)
>> +++ cfe/trunk/tools/driver/driver.cpp Fri Jan 15 16:29:34 2016
>> @@ -290,9 +290,9 @@ static void SetInstallDir(SmallVectorImp
>>    if (CanonicalPrefixes)
>>      llvm::sys::fs::make_absolute(InstalledPath);
>>
>> -  InstalledPath = llvm::sys::path::parent_path(InstalledPath);
>> -  if (llvm::sys::fs::exists(InstalledPath.c_str()))
>> -    TheDriver.setInstalledDir(InstalledPath);
>> +  StringRef
>> InstalledPathParent(llvm::sys::path::parent_path(InstalledPath));
>> +  if (llvm::sys::fs::exists(InstalledPathParent))
>> +    TheDriver.setInstalledDir(InstalledPathParent);
>>  }
>>
>>  static int ExecuteCC1Tool(ArrayRef<const char *> argv, StringRef Tool) {
>>
>>
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