r207696 - PR19601: std::remove_if does not really remove the elements.

[Jordan Rose]

My hypothesis for how this was working: std::remove_if reorders elements using std::move, so we were getting lucky that -no-integrated-as wasn't the last argument and something else got moved on top of it. We'd have duplicates of the last few arguments (because they got moved earlier), but that wouldn't show -no-integrated-as.

Jordan


On Apr 30, 2014, at 14:09, Richard Smith <richard at metafoo.co.uk> wrote:

> This needs a test case. This code has already been committed, incorrectly, twice before this revision; the existing test case clearly doesn't actually cover it properly.
> 
> 
> On Wed, Apr 30, 2014 at 12:59 PM, Arnaud A. de Grandmaison <arnaud.adegm at gmail.com> wrote:
> Author: aadg
> Date: Wed Apr 30 14:59:22 2014
> New Revision: 207696
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=207696&view=rev
> Log:
> PR19601: std::remove_if does not really remove the elements.
> 
> It moves them at the end of the range instead, so an extra erase is needed.
> 
> It is strange that this code works without the erase. On the other hand, removing the remove_if will make fail some tests.
> 
> Modified:
>     cfe/trunk/lib/Tooling/CompilationDatabase.cpp
> 
> Modified: cfe/trunk/lib/Tooling/CompilationDatabase.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Tooling/CompilationDatabase.cpp?rev=207696&r1=207695&r2=207696&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Tooling/CompilationDatabase.cpp (original)
> +++ cfe/trunk/lib/Tooling/CompilationDatabase.cpp Wed Apr 30 14:59:22 2014
> @@ -238,8 +238,9 @@ static bool stripPositionalArgs(std::vec
> 
>    // Remove -no-integrated-as; it's not used for syntax checking,
>    // and it confuses targets which don't support this option.
> -  std::remove_if(Args.begin(), Args.end(),
> -                 MatchesAny(std::string("-no-integrated-as")));
> +  Args.erase(std::remove_if(Args.begin(), Args.end(),
> +                            MatchesAny(std::string("-no-integrated-as"))),
> +             Args.end());
> 
>    const std::unique_ptr<driver::Compilation> Compilation(
>        NewDriver->BuildCompilation(Args));
> 
> 
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