[clang] Do not warn about unused plugin flags. (PR #88948)

[Michael Kruse via cfe-commits]

https://github.com/Meinersbur created https://github.com/llvm/llvm-project/pull/88948

Plugins are not loaded without the -cc1 phase. Do not report them when running on an assembly file or when linking. Many build tools add these options to all driver invocations, including LLVM's build system.

Fixes #88173

>From e5b10d3eba126454824c9f6fac4a575e07366ae6 Mon Sep 17 00:00:00 2001
From: Michael Kruse <llvm-project at meinersbur.de>
Date: Tue, 16 Apr 2024 19:50:35 +0200
Subject: [PATCH] Do not warn about unused plugin flags.

Plugins are not loaded without the -cc1 phase. Do not report them when
running on a assembly file or when linking. Many build tools add these
options to all driver invocations. See GH #88173.
---
 clang/include/clang/Driver/Options.td | 6 +++---
 clang/test/Driver/clang-s-plugin.s    | 5 +++++
 2 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 clang/test/Driver/clang-s-plugin.s

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index e24626913add76..c1d85c527d437b 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3630,14 +3630,14 @@ defm rwpi : BoolFOption<"rwpi",
           "Generate read-write position independent code (ARM only)">,
   NegFlag<SetFalse, [], [ClangOption, FlangOption, CC1Option]>>;
 def fplugin_EQ : Joined<["-"], "fplugin=">, Group<f_Group>,
-  Flags<[NoXarchOption]>, MetaVarName<"<dsopath>">,
+  Flags<[NoXarchOption, NoArgumentUnused]>, MetaVarName<"<dsopath>">,
   HelpText<"Load the named plugin (dynamic shared object)">;
 def fplugin_arg : Joined<["-"], "fplugin-arg-">,
-  MetaVarName<"<name>-<arg>">,
+  MetaVarName<"<name>-<arg>">, Flags<[NoArgumentUnused]>,
   HelpText<"Pass <arg> to plugin <name>">;
 def fpass_plugin_EQ : Joined<["-"], "fpass-plugin=">,
   Group<f_Group>, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
-  MetaVarName<"<dsopath>">,
+  MetaVarName<"<dsopath>">, Flags<[NoArgumentUnused]>,
   HelpText<"Load pass plugin from a dynamic shared object file (only with new pass manager).">,
   MarshallingInfoStringVector<CodeGenOpts<"PassPlugins">>;
 defm tocdata : BoolOption<"m","tocdata",
diff --git a/clang/test/Driver/clang-s-plugin.s b/clang/test/Driver/clang-s-plugin.s
new file mode 100644
index 00000000000000..81169b7bc5bbc8
--- /dev/null
+++ b/clang/test/Driver/clang-s-plugin.s
@@ -0,0 +1,5 @@
+// RUN: %clang -### -c -fpass-plugin=bar.so -fplugin=bar.so -fplugin-arg-bar-option -Werror %s 2>&1 | FileCheck %s
+
+// Plugins are only relevant for the -cc1 phase. No warning should be raised
+// when applied to assembly files. See GH #88173.
+// CHECK-NOT: argument unused during compilation