From e05edb19adbfd1b24f58d583e4b5b4d742f982ee Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Fri, 2 Sep 2022 09:51:02 -0700
Subject: [PATCH] [Driver] Unsupport --print-multiarch

* If GCC is configured with `--disable-multi-arch`, `--print-multiarch` output is an empty line.
* If GCC is configured with `--enable-multi-arch`, `--print-multiarch` output may be a normalized triple or (on Debian, 'vendor' is omitted) `x86_64-linux-gnu`.

The Clang support D101400 just prints the Debian multiarch style triple
unconditionally, but the string is not really expected for non-Debian systems.

AIUI many Linux distributions and non-Linux OSes don't configure GCC with `--enable-multi-arch`.
Instead of getting us in the trouble of supporting all kinds of variants, drop the support as before D101400.

Close https://github.com/llvm/llvm-project/issues/51469

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D133170
---
 clang/include/clang/Driver/Options.td |  5 +++--
 clang/lib/Driver/Driver.cpp           |  6 ------
 clang/test/Driver/print-multiarch.c   | 10 +++++-----
 3 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index d921ea5d5da9..1112e0187758 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4069,8 +4069,9 @@ def print_target_triple : Flag<["-", "--"], "print-target-triple">,
   HelpText<"Print the normalized target triple">, Flags<[FlangOption]>;
 def print_effective_triple : Flag<["-", "--"], "print-effective-triple">,
   HelpText<"Print the effective target triple">, Flags<[FlangOption]>;
-def print_multiarch : Flag<["-", "--"], "print-multiarch">,
-  HelpText<"Print the multiarch target triple">;
+// GCC --disable-multiarch, GCC --enable-multiarch (upstream and Debian
+// specific) have different behaviors. We choose not to support the option.
+def : Flag<["-", "--"], "print-multiarch">, Flags<[Unsupported]>;
 def print_prog_name_EQ : Joined<["-", "--"], "print-prog-name=">,
   HelpText<"Print the full program path of <name>">, MetaVarName<"<name>">;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 554e6b890281..ba359a1d31a5 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2152,12 +2152,6 @@ bool Driver::HandleImmediateArgs(const Compilation &C) {
     return false;
   }
 
-  if (C.getArgs().hasArg(options::OPT_print_multiarch)) {
-    llvm::outs() << TC.getMultiarchTriple(*this, TC.getTriple(), SysRoot)
-                 << "\n";
-    return false;
-  }
-
   if (C.getArgs().hasArg(options::OPT_print_targets)) {
     llvm::TargetRegistry::printRegisteredTargetsForVersion(llvm::outs());
     return false;
diff --git a/clang/test/Driver/print-multiarch.c b/clang/test/Driver/print-multiarch.c
index 8638c9a155a3..5bbfcb0030c2 100644
--- a/clang/test/Driver/print-multiarch.c
+++ b/clang/test/Driver/print-multiarch.c
@@ -1,6 +1,6 @@
-// Check the output of -print-multiarch.
+/// GCC --disable-multiarch, GCC --enable-multiarch (upstream and Debian specific) have different behaviors.
+/// We choose not to support the option.
 
-// RUN: %clang -print-multiarch --target=x86_64-unknown-linux-gnu \
-// RUN:        -resource-dir=%S/Inputs/resource_dir \
-// RUN:      | FileCheck --check-prefix=PRINT-MULTIARCH %s
-// PRINT-MULTIARCH: {{^}}x86_64-linux-gnu{{$}}
+// RUN: not %clang -print-multiarch --target=x86_64-unknown-linux-gnu 2>&1 | FileCheck %s
+
+// CHECK: error: unsupported option '-print-multiarch'