[flang-commits] [clang] [flang] [flang][Driver] Support -nostdlib and -nodefaultlibs (PR #108868)

[Mészáros Gergely via flang-commits]

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@@ -5572,7 +5572,8 @@ def : Flag<["-"], "nocudalib">, Alias<nogpulib>;
 def gpulibc : Flag<["-"], "gpulibc">, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
   HelpText<"Link the LLVM C Library for GPUs">;
 def nogpulibc : Flag<["-"], "nogpulibc">, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>;
-def nodefaultlibs : Flag<["-"], "nodefaultlibs">;
+def nodefaultlibs : Flag<["-"], "nodefaultlibs">,
+  Visibility<[ClangOption, FlangOption, CLOption, DXCOption]>;
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Maetveis wrote:

With this change in Options.td:

```diff
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index cb96b5daed9d3a2..842e6c2e6233adb 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5644,4 +5644,3 @@ def gpulibc : Flag<["-"], "gpulibc">, Visibility<[ClangOption, CC1Option, FlangO
 def nogpulibc : Flag<["-"], "nogpulibc">, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>;
-def nodefaultlibs : Flag<["-"], "nodefaultlibs">,
-  Visibility<[ClangOption, FlangOption, CLOption, DXCOption]>;
+def nodefaultlibs : Flag<["-"], "nodefaultlibs">;
 def nodriverkitlib : Flag<["-"], "nodriverkitlib">;
 ```
 
I'm getting:
 
```console
> build\bin\clang-cl.exe -nodefaultlibs asd.o
clang-cl: warning: unknown argument ignored in clang-cl: '-nodefaultlibs' [-Wunknown-argument]
```

without it I don't get a warning.

The comment at Options.td:74 also seems to suggest the default is only the gcc compatible driver. https://github.com/llvm/llvm-project/blob/c3536b263f253a69fb336fb0617ee33a01a5c5dd/clang/include/clang/Driver/Options.td#L74-L77

https://github.com/llvm/llvm-project/pull/108868