[NFC][clangd] Use table to collect option aliases

[ychen]

Summary

• Suppress a lot of -Wtautological-compare warning
• Speed up file build a little bit

[ychen]

ping

[kadircet]

thanks, lgtm!

[uabelho]

clang-tools-extra/clangd/CompileCommands.cpp

478

gcc warns about casting away "const" here.
Would it break anything to simply change the type of AliasArgs in the AliasTable to "const char *" and skip this void* cast?

[ychen]

clang-tools-extra/clangd/CompileCommands.cpp

478

gcc warns about casting away "const" here.
Would it break anything to simply change the type of AliasArgs in the AliasTable to "const char *" and skip this void* cast?

Thanks for the report. Fixed in 4f30a5269696.

clang-tools-extra/clangd/CompileCommands.cpp

auto AddAlias = [&](DriverID Self, DriverID T) {
       PrevAlias[Self] = T;
       NextAlias[T] = Self;
     };
     // Also grab prefixes for each option, these are not fully exposed.
     const char *const *Prefixes[DriverID::LastOption] = {nullptr};
 #define PREFIX(NAME, VALUE) static const char *const NAME[] = VALUE;
 #define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
                HELP, METAVAR, VALUES)                                          \
-  if (DriverID::OPT_##ALIAS != DriverID::OPT_INVALID && ALIASARGS == nullptr)  \
-    AddAlias(DriverID::OPT_##ID, DriverID::OPT_##ALIAS);                       \
   Prefixes[DriverID::OPT_##ID] = PREFIX;
 #include "clang/Driver/Options.inc"
 #undef OPTION
 #undef PREFIX
 
+    struct {
+      DriverID ID;
+      DriverID AliasID;
+      void *AliasArgs;
+    } AliasTable[] = {
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
+               HELP, METAVAR, VALUES)                                          \
+  {DriverID::OPT_##ID, DriverID::OPT_##ALIAS, (void *)ALIASARGS},
+#include "clang/Driver/Options.inc"
+#undef OPTION
+    };
+    for (auto &E : AliasTable)
+      if (E.AliasID != DriverID::OPT_INVALID && E.AliasArgs == nullptr)
+        AddAlias(E.ID, E.AliasID);
+
     auto Result = std::make_unique<TableTy>();
     // Iterate over distinct options (represented by the canonical alias).
     // Every spelling of this option will get the same set of rules.
     for (unsigned ID = 1 /*Skip INVALID */; ID < DriverID::LastOption; ++ID) {
       if (PrevAlias[ID] || ID == DriverID::OPT_Xclang)
         continue; // Not canonical, or specially handled.
       llvm::SmallVector<Rule> Rules;
       // Iterate over each alias, to add rules for parsing it.