mstorsjo added inline comments.

================
Comment at: lldb/test/Shell/Target/dependent-modules-nodupe-windows.test:7
+# RUN: %clang_host -g0 -O0 -shared %S/Inputs/shlib.c -o %t.shlib.dll
+# RUN: %clang_host -g0 -O0 %S/Inputs/main.c %t.shlib.dll -o %t.main.exe
+# RUN: %lldb -b -o "#before" -o "target modules list" -o "b main" -o run \
----------------
alvinhochun wrote:
> mstorsjo wrote:
> > alvinhochun wrote:
> > > mstorsjo wrote:
> > > > alvinhochun wrote:
> > > > > mstorsjo wrote:
> > > > > > mstorsjo wrote:
> > > > > > > Unfortunately, this aspect of the test doesn't work as is on 
> > > > > > > Windows.
> > > > > > > 
> > > > > > > By default (in msvc builds), clang invokes link.exe here, but 
> > > > > > > link.exe can't take `%t.shlib.dll` as input file to the linker, 
> > > > > > > as it requires an import library.
> > > > > > > 
> > > > > > > If we would assume that lld is available, we could run the 
> > > > > > > linking command with `-fuse-ld=lld` - however that on its own 
> > > > > > > isn't enough, as lld only allows linking against DLLs when run 
> > > > > > > with the `-lldmingw` flag. We can add `-fuse-ld=lld 
> > > > > > > -Wl,-lldmingw` here to fix that, but that would break testing in 
> > > > > > > mingw environments, as `-lldmingw` isn't a valid option on the 
> > > > > > > mingw lld driver.
> > > > > > > 
> > > > > > > Likewise, we could create a proper import library by adding 
> > > > > > > `-Wl,-implib:%t.shlib.lib` on the first command above, but that 
> > > > > > > doesn't work in mingw mode either, as it would have to be 
> > > > > > > `-Wl,--out-implib=%t.shlib.lib` instead.
> > > > > > > 
> > > > > > > In practice, running the lldb tests in mingw mode is not entirely 
> > > > > > > supported, while they do pass cleanly in MSVC mode (and there's a 
> > > > > > > buildbot testing this configuration) - but I would like to work 
> > > > > > > towards making things work better in the mingw configuration too.
> > > > > > > 
> > > > > > > There's a different substitution, `%build`, which invokes the 
> > > > > > > `lldb/test/Shell/helpers/build.py` script, which abstracts a 
> > > > > > > bunch of boilerplate details mostly relevant for windows targets 
> > > > > > > (like creating PDB debug info files); the easiest at this point 
> > > > > > > would probably be to extend that script with options for creating 
> > > > > > > import libraries.
> > > > > > > 
> > > > > > > For testing with mingw, I'm currently using this out of tree 
> > > > > > > patch for that script too:
> > > > > > > ```
> > > > > > > diff --git a/lldb/test/Shell/helper/build.py 
> > > > > > > b/lldb/test/Shell/helper/build.py
> > > > > > > index 96684b7b3e66..f138b00bee9e 100755
> > > > > > > --- a/lldb/test/Shell/helper/build.py
> > > > > > > +++ b/lldb/test/Shell/helper/build.py
> > > > > > > @@ -191,7 +191,10 @@ def find_toolchain(compiler, tools_dir):
> > > > > > >      if compiler == 'any':
> > > > > > >          priorities = []
> > > > > > >          if sys.platform == 'win32':
> > > > > > > -            priorities = ['clang-cl', 'msvc', 'clang', 'gcc']
> > > > > > > +            if 'gcc' in sys.version.lower():
> > > > > > > +                priorities = ['clang', 'gcc', 'clang-cl', 'msvc']
> > > > > > > +            else:
> > > > > > > +                priorities = ['clang-cl', 'msvc', 'clang', 'gcc']
> > > > > > >          else:
> > > > > > >              priorities = ['clang', 'gcc', 'clang-cl']
> > > > > > >          for toolchain in priorities:
> > > > > > > ```
> > > > > > > (This is a bit hacky, since it uses the build type of the python 
> > > > > > > interpreter to switch the preference between clang-cl and clang.)
> > > > > > > 
> > > > > > > Alternatively, we could maybe add a separate substitution that 
> > > > > > > expands into either `-implib:` or `--out-implib=`, but I'm not 
> > > > > > > sure if we can guess which one will be the right one either, 
> > > > > > > while the build.py helper script probably can do better.
> > > > > > I forgot to mention; see https://reviews.llvm.org/D129455 for some 
> > > > > > earlier discussion about other aspects (symbol table vs dwarf vs 
> > > > > > PDB) for windows testcases in lldb.
> > > > > Re different options on msvc vs mingw, how about using the `%if` 
> > > > > substitution (https://www.llvm.org/docs/TestingGuide.html)? We can 
> > > > > use it to check for the `windows-msvc` feature to apply options 
> > > > > conditionally.
> > > > Oh, I guess that would work too - it does litter the individual tests 
> > > > with the conditions instead of hiding it in `build.py`, but probably is 
> > > > acceptable too.
> > > The commands should become this:
> > > 
> > > ```
> > > # RUN: %clang_host -g0 -O0 -shared %S/Inputs/shlib.c -o %t.shlib.dll %if 
> > > windows-msvc %{-Wl,-implib:%t.shlib.lib}
> > > # RUN: %clang_host -g0 -O0 %S/Inputs/main.c -o %t.main.exe %if 
> > > windows-msvc %{%t.shlib.lib} %else %{%t.shlib.dll}
> > > ```
> > This form works, and keeps it to just one conditional:
> > ```
> > # RUN: %clang_host -g0 -O0 -shared %S/Inputs/shlib.c -o %t.shlib.dll %if 
> > windows-msvc %{-Wl,-implib:%t.shlib.lib%} %else 
> > %{-Wl,--out-implib=%t.shlib.lib%}
> > # RUN: %clang_host -g0 -O0 %S/Inputs/main.c %t.shlib.lib -o %t.main.exe
> > ```
> Oh yeah, this does feel nicer. Have you already tested it?
Yes, I tested the form I quoted above, and it works with both msvc and mingw 
based setups.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D134581/new/

https://reviews.llvm.org/D134581

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