[PATCH] D144190: [AIX][clang] Storage Locations for Constant Pointers

[Hubert Tong via Phabricator via cfe-commits]

hubert.reinterpretcast added inline comments.


================
Comment at: clang/lib/Driver/ToolChains/Clang.cpp:5250
 
+  if (Args.hasArg(options::OPT_mroptr) || Args.hasArg(options::OPT_mno_roptr)) {
+    bool HasRoptr =
----------------
qiongsiwu1 wrote:
> hubert.reinterpretcast wrote:
> > This only checks for `-m[no-]roptr` when the front-end is invoked. When the driver is used just for linking, we get no diagnostic at all for using these options on other platforms.
> > 
> > @MaskRay:
> > 
> > As Clang code owner for the Driver, are you concerned if platform-specific options are sometimes silently ignored on other platforms? Is there a better place for the diagnostic?
> > 
> > For info, in this case, the option would have effects on AIX at both compile-from-C/C++ time and at link time. 
> > 
> > Also, should `-Wunused-command-line-argument` warnings be generated for cases where the option has no effect (e.g., `-emit-llvm` or `-fsyntax-only`)? I think `-flto` is a bit of an exception because it may be unfriendly to expect users to change other aspects of their compile invocations when adding `-flto`. At the same time, it can be argued instead that generating a `-Wunused-command-line-argument` warning for "back-end" options on `-flto` compiles helps the user realize that they need to provide the option on their link step.
> > 
> @MaskRay May I ask for your input on this issue where platform-specific options are silently ignored on other platforms? What is our current opinion on where these checks/diagnostics should go? 
> 
> Thanks!! 
Hi @MaskRay,

Thank you for your comments so far. I am particularly interested diagnostics for cases where the option does not take effect. We are hoping for a good approach to implement the diagnostic when the option is used on non-AIX platforms (without the current issue that we only check when the front-end is invoked). Additionally, I would like your opinion on whether a diagnostic is warranted for cases like `-emit-llvm` or `-fsyntax-only`. What existing command-line options are you aware of that can serve as a good design template that we can apply here?

Thanks again,
HT



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  https://reviews.llvm.org/D144190/new/

https://reviews.llvm.org/D144190