[lld] r182912 - [WinLink][Driver] Handle file extensions and defualt output file name.

[David Blaikie]

On Thu, May 30, 2013 at 9:16 AM, Reid Kleckner <rnk at google.com> wrote:
> On Thu, May 30, 2013 at 2:00 AM, Rui Ueyama <ruiu at google.com> wrote:
>>
>> Author: ruiu
>> Date: Thu May 30 01:00:10 2013
>> New Revision: 182912
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=182912&view=rev
>> Log:
>> [WinLink][Driver] Handle file extensions and defualt output file name.
>>
>> Modified:
>>     lld/trunk/lib/Driver/WinLinkDriver.cpp
>>
>> Modified: lld/trunk/lib/Driver/WinLinkDriver.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/lib/Driver/WinLinkDriver.cpp?rev=182912&r1=182911&r2=182912&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/lib/Driver/WinLinkDriver.cpp (original)
>> +++ lld/trunk/lib/Driver/WinLinkDriver.cpp Thu May 30 01:00:10 2013
>> @@ -16,6 +16,7 @@
>>  #include "llvm/ADT/StringSwitch.h"
>>  #include "llvm/Option/Arg.h"
>>  #include "llvm/Option/Option.h"
>> +#include "llvm/Support/PathV2.h"
>>
>>  #include "lld/Driver/Driver.h"
>>  #include "lld/ReaderWriter/PECOFFTargetInfo.h"
>> @@ -72,6 +73,21 @@ llvm::COFF::WindowsSubsystem strToWinSub
>>        .Default(llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN);
>>  }
>>
>> +// Add ".obj" extension if the given path name has no file extension.
>> +StringRef canonicalizeInputFileName(StringRef path) {
>> +  if (llvm::sys::path::extension(path).empty())
>> +    return path.str() + ".obj";
>
>
> Isn't this a use-after-return?  path.str() makes a temp std::string, which
> is concatenated.  Then we construct the StringRef from the string.
>
> Probably the right thing is to take a std::string& and modify it in place.

Pushing the limits a little:

Alternatively - take a std::string by value, mutate it, then return it
by value. We only actually care about the performance of Clang/LLVM
when built as C++11 anyway (though, true, we'd need some way to say
"std::move" (should probably have some LLVM compatibility function
that's a no-op in C++98 and does std::move in C++11) at the call site
- and maybe that's more hassle than its worth if every caller likely
wants to mutate an existing string anyway)

>
>>
>> +  return path;
>> +}
>> +
>> +// Replace a file extension with ".exe". If the given file has no
>> +// extension, just add ".exe".
>> +StringRef getDefaultOutputFileName(StringRef path) {
>> +  StringRef ext = llvm::sys::path::extension(path);
>> +  StringRef filename = ext.empty() ? path : path.drop_back(ext.size());
>> +  return filename.str() + ".exe";
>
>
> ditto?
>
>>
>> +}
>> +
>>  } // namespace
>>
>>
>> @@ -141,16 +157,26 @@ bool WinLinkDriver::parse(int argc, cons
>>      info.setOutputPath(outpath->getValue());
>>
>>    // Add input files
>> +  std::vector<StringRef> inputPaths;
>>    for (llvm::opt::arg_iterator it =
>> parsedArgs->filtered_begin(OPT_INPUT),
>>                                 ie = parsedArgs->filtered_end();
>>         it != ie; ++it) {
>> -    info.appendInputFile((*it)->getValue());
>> +    inputPaths.push_back((*it)->getValue());
>>    }
>>
>>    // Arguments after "--" are also input files
>>    if (doubleDashPosition > 0)
>>      for (int i = doubleDashPosition + 1; i < argc; ++i)
>> -      info.appendInputFile(argv[i]);
>> +      inputPaths.push_back(argv[i]);
>> +
>> +  // Add ".obj" extension for those who have no file extension.
>> +  for (const StringRef &path : inputPaths)
>> +    info.appendInputFile(canonicalizeInputFileName(path));
>> +
>> +  // If -out option was not specified, the default output file name is
>> +  // constructed by replacing an extension with ".exe".
>> +  if (info.outputPath().empty() && !inputPaths.empty())
>> +    info.setOutputPath(getDefaultOutputFileName(inputPaths[0]));
>>
>>    // Validate the combination of options used.
>>    return info.validate(diagnostics);
>>
>>
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>
>
>
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