llvm dev - Feb 2015 - [LLVMdev] Formatting of command line option help text

llvm-link and clang both have a -o option with similar meaning, but the
help text describes it differently.

llvm-link describes it as:

-o=<filename>

and clang describes it as

-o <file>

with no '=' between the option and the parameter.

When I try using the command line options library, it comes out the same
way as llvm-link, with no apparent method of getting it to come out the
other way. This might be just a minor cosmetic question, but I've a feeling
it actually points to a significant gap in my understanding of the command
line options library, because when I tried checking the clang source code
for the answer, the only relevant reference I could find was in some
configuration or DSL file whose syntax and function I'm not familiar with.

How exactly is clang getting that effect?
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The LLVM toolchain, and many small LLVM based tools (like clang-format) use
libSupport’s cl::ParseCommandLineOptions and related APIs for command line
parsing. This results in the behavior you see with llvm-link.

Clang, lld, and some of the other higher level tools use a TableGen driven
process implemented in libOption.

So, you get different help formats because the two APIs are completely
independent.

-Chris
> On Feb 4, 2015, at 6:53 AM, Russell Wallace <russell.wallace at
gmail.com> wrote:
> 
> llvm-link and clang both have a -o option with similar meaning, but the
help text describes it differently.
> 
> llvm-link describes it as:
> 
> -o=<filename>
> 
> and clang describes it as
> 
> -o <file>
> 
> with no '=' between the option and the parameter.
> 
> When I try using the command line options library, it comes out the same
way as llvm-link, with no apparent method of getting it to come out the other
way. This might be just a minor cosmetic question, but I've a feeling it
actually points to a significant gap in my understanding of the command line
options library, because when I tried checking the clang source code for the
answer, the only relevant reference I could find was in some configuration or
DSL file whose syntax and function I'm not familiar with.
> 
> How exactly is clang getting that effect?
> 
> 
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