[PATCH] D93702: [clang][cli] NFC: Make marshalling macros reusable

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith added inline comments.


================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:3040
 
-#define OPTION_WITH_MARSHALLING(                                               \
-    PREFIX_TYPE, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,        \
-    HELPTEXT, METAVAR, VALUES, SPELLING, ALWAYS_EMIT, KEYPATH, DEFAULT_VALUE,  \
-    IMPLIED_CHECK, IMPLIED_VALUE, NORMALIZER, DENORMALIZER, MERGER, EXTRACTOR, \
-    TABLE_INDEX)                                                               \
-  if ((FLAGS)&options::CC1Option) {                                            \
-    this->KEYPATH = MERGER(this->KEYPATH, DEFAULT_VALUE);                      \
-    if (IMPLIED_CHECK)                                                         \
-      this->KEYPATH = MERGER(this->KEYPATH, IMPLIED_VALUE);                    \
-    if (auto MaybeValue =                                                      \
-            NORMALIZER(OPT_##ID, TABLE_INDEX, Args, Diags, Success))           \
-      this->KEYPATH = MERGER(                                                  \
-          this->KEYPATH, static_cast<decltype(this->KEYPATH)>(*MaybeValue));   \
-  }
-
+#define OPTION_WITH_MARSHALLING PARSE_OPTION_WITH_MARSHALLING
 #include "clang/Driver/Options.inc"
----------------
jansvoboda11 wrote:
> dexonsmith wrote:
> > One concern I have with this change is that the macro is using local variable names; it really would be better to have the macro content local to the function(s) where the variables are defined.
> > 
> > Can you give more context about why this has to be called from another place? Maybe there's another way to solve the problem.
> I've provided more context here: D93701.
> 
> We can solve the problem with implicit use of local variables inside the macro by promoting them to macro parameters.
> This will make the forwarding call from `OPTION_WITH_MARSHALLING` to `PARSE_OPTION_WITH_MARSHALLING` longer, as it will need to spell out all parameters, but it would solve your concern I think.
I like that idea. That approach also allows you to drop unused parameters entirely in `PARSE_OPTIONS_WITH_MARSHALLING` (only forward the parameters that get used).


================
Comment at: clang/lib/Frontend/CompilerInvocation.cpp:3331-3332
+
+#undef GENERATE_OPTION_WITH_MARSHALLING
+#undef PARSE_OPTION_WITH_MARSHALLING
----------------
I like the idea of `#undef`'ing these macros to make their scope of use clear, but I'm not sure doing it at the end of file is adding a lot of value.

Is there a way of moving the call sites for each to be next to each other in the file, so you can `#define` and then `#undef` in a more limited scope? E.g.,
```
// maybe other content...

#define PARSE_OPTION_WITH_MARSHALLING(...) ...
void f1(...) { /* use PARSE_OPTION_WITH_MARSHALLING */ }
void f2(...) { /* use PARSE_OPTION_WITH_MARSHALLING */ }
#undef PARSE_OPTION_WITH_MARSHALLING

// maybe other content...

#define GENERATE_OPTION_WITH_MARSHALLING(...) ...
void f3(...) { /* use GENERATE_OPTION_WITH_MARSHALLING*/ }
void f4(...) { /* use GENERATE_OPTION_WITH_MARSHALLING*/ }
#undef GENERATE_OPTION_WITH_MARSHALLING

// maybe other content...
```
(If so, the code movement should be done in a separate NFC prep commit...)


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93702/new/

https://reviews.llvm.org/D93702