clang-cl: Remove /Zd flag

[thakis]

Summary

cl.exe doesn't understand Zd (in either MSVC 2017 or 2019), so neiter
should we. It used to do the same as -gline-tables-only which is
exposed as clang-cl flag as well, so if you want this behavior, use
gline-tables-only. That makes it clear that it's a clang-cl-only flag
that won't work with cl.exe.

Motivated by the discussion in D92958.

[aeubanks]

lgtm, but perhaps Reid should take a look

clang/docs/ReleaseNotes.rst

127

[rnk]

lgtm

clang/docs/ReleaseNotes.rst

- On ELF, ``-gz`` now defaults to ``-gz=zlib`` with the integrated assembler.
   It produces ``SHF_COMPRESSED`` style compression of debug information. GNU
   binutils 2.26 or newer, or lld is required to link produced object files. Use
   ``-gz=zlib-gnu`` to get the old behavior.
 - Now that `this` pointers are tagged with `nonnull` and `dereferenceable(N)`,
   `-fno-delete-null-pointer-checks` has gained the power to remove the
   `nonnull` attribute on `this` for configurations that need it to be nullable.
 - ``-gsplit-dwarf`` no longer implies ``-g2``.
 
+Removed Compiler Flags
+-------------------------
+
+The following options no longer exist.
+
+- clang-cl's ``/Zd`` flag no longer exist. But ``-gline-tables-only`` still
+  exists and does the same thing.
+
 New Pragmas in Clang
 --------------------
 
 - ...
 
 Attribute Changes in Clang
 --------------------------
 

clang/include/clang/Driver/Options.td

 def _SLASH_Zc_twoPhase : CLFlag<"Zc:twoPhase">,
   HelpText<"Enable two-phase name lookup in templates">,
   Alias<fno_delayed_template_parsing>;
 def _SLASH_Zc_twoPhase_ : CLFlag<"Zc:twoPhase-">,
   HelpText<"Disable two-phase name lookup in templates (default)">,
   Alias<fdelayed_template_parsing>;
 def _SLASH_Z7 : CLFlag<"Z7">,
   HelpText<"Enable CodeView debug information in object files">;
-def _SLASH_Zd : CLFlag<"Zd">,
-  HelpText<"Emit debug line number tables only">;
 def _SLASH_Zi : CLFlag<"Zi">, Alias<_SLASH_Z7>,
   HelpText<"Like /Z7">;
 def _SLASH_Zp : CLJoined<"Zp">,
   HelpText<"Set default maximum struct packing alignment">,
   Alias<fpack_struct_EQ>;
 def _SLASH_Zp_flag : CLFlag<"Zp">,
   HelpText<"Set default maximum struct packing alignment to 1">,
   Alias<fpack_struct_EQ>, AliasArgs<["1"]>;

clang/lib/Driver/ToolChains/Clang.cpp

void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
   // This controls whether or not we emit stack-protector instrumentation.
   // In MSVC, Buffer Security Check (/GS) is on by default.
   if (!isNVPTX && Args.hasFlag(options::OPT__SLASH_GS, options::OPT__SLASH_GS_,
                                /*Default=*/true)) {
     CmdArgs.push_back("-stack-protector");
     CmdArgs.push_back(Args.MakeArgString(Twine(LangOptions::SSPStrong)));
   }
 
-  // Emit CodeView if -Z7, -Zd, or -gline-tables-only are present.
-  if (Arg *DebugInfoArg =
-          Args.getLastArg(options::OPT__SLASH_Z7, options::OPT__SLASH_Zd,
+  // Emit CodeView if -Z7 or -gline-tables-only are present.
+  if (Arg *DebugInfoArg = Args.getLastArg(options::OPT__SLASH_Z7,
                                           options::OPT_gline_tables_only)) {
     *EmitCodeView = true;
     if (DebugInfoArg->getOption().matches(options::OPT__SLASH_Z7))
       *DebugInfoKind = codegenoptions::LimitedDebugInfo;
     else
       *DebugInfoKind = codegenoptions::DebugLineTablesOnly;
   } else {
     *EmitCodeView = false;
   }

clang/lib/Driver/ToolChains/MSVC.cpp

if (TC.getVFS().exists(CRTPath))
     CmdArgs.push_back(Args.MakeArgString("-libpath:" + CRTPath));
 
   if (!C.getDriver().IsCLMode() && Args.hasArg(options::OPT_L))
     for (const auto &LibPath : Args.getAllArgValues(options::OPT_L))
       CmdArgs.push_back(Args.MakeArgString("-libpath:" + LibPath));
 
   CmdArgs.push_back("-nologo");
 
-  if (Args.hasArg(options::OPT_g_Group, options::OPT__SLASH_Z7,
-                  options::OPT__SLASH_Zd))
+  if (Args.hasArg(options::OPT_g_Group, options::OPT__SLASH_Z7))
     CmdArgs.push_back("-debug");
 
   // Pass on /Brepro if it was passed to the compiler.
   // Note that /Brepro maps to -mno-incremental-linker-compatible.
   bool DefaultIncrementalLinkerCompatible =
       C.getDefaultToolChain().getTriple().isWindowsMSVCEnvironment();
   if (!Args.hasFlag(options::OPT_mincremental_linker_compatible,
                     options::OPT_mno_incremental_linker_compatible,

clang/test/Driver/cl-options.c

 // RUN: %clang_cl /Zi /c -### -- %s 2>&1 | FileCheck -check-prefix=Zi %s
 // Zi: "-gcodeview"
 // Zi: "-debug-info-kind=limited"
 
 // RUN: %clang_cl /Z7 /c -### -- %s 2>&1 | FileCheck -check-prefix=Z7 %s
 // Z7: "-gcodeview"
 // Z7: "-debug-info-kind=limited"
 
-// RUN: %clang_cl /Zd /c -### -- %s 2>&1 | FileCheck -check-prefix=Z7GMLT %s
-// Z7GMLT: "-gcodeview"
-// Z7GMLT: "-debug-info-kind=line-tables-only"
-
 // RUN: %clang_cl -gline-tables-only /c -### -- %s 2>&1 | FileCheck -check-prefix=ZGMLT %s
 // ZGMLT: "-gcodeview"
 // ZGMLT: "-debug-info-kind=line-tables-only"
 
 // RUN: %clang_cl /c -### -- %s 2>&1 | FileCheck -check-prefix=BreproDefault %s
 // BreproDefault: "-mincremental-linker-compatible"
 
 // RUN: %clang_cl /Brepro- /Brepro /c '-###' -- %s 2>&1 | FileCheck -check-prefix=Brepro %s