From 25fe428ed27e89cd5ff9f7c6aee9d32e2e73faa7 Mon Sep 17 00:00:00 2001
From: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
Date: Thu, 7 Oct 2021 11:24:20 +0800
Subject: [PATCH] system_config: fix clang version output on Linux

If you have Homebrew LLVM installed, `brew config` will show

    Clang: 12.0.1 build (parse error)

because Homebrew LLVM does not give a build number. Some installations
from the system package manager do have this information, so let's show
it if it's available but skip complaining if not.

I've kept the original code for macOS because we always expect Apple's
build number to show there.
---
 Library/Homebrew/extend/os/mac/system_config.rb | 9 ++++++++-
 Library/Homebrew/system_config.rb               | 7 +++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/Library/Homebrew/extend/os/mac/system_config.rb b/Library/Homebrew/extend/os/mac/system_config.rb
index d45eb2e0f5..1e22d916ea 100644
--- a/Library/Homebrew/extend/os/mac/system_config.rb
+++ b/Library/Homebrew/extend/os/mac/system_config.rb
@@ -7,7 +7,7 @@ module SystemConfig
   class << self
     include SystemCommand::Mixin
 
-    undef describe_homebrew_ruby
+    undef describe_homebrew_ruby, describe_clang
 
     def describe_homebrew_ruby
       s = describe_homebrew_ruby_version
@@ -19,6 +19,13 @@ module SystemConfig
       end
     end
 
+    def describe_clang
+      return "N/A" if clang.null?
+
+      clang_build_info = clang_build.null? ? "(parse error)" : clang_build
+      "#{clang} build #{clang_build_info}"
+    end
+
     def xcode
       @xcode ||= if MacOS::Xcode.installed?
         xcode = MacOS::Xcode.version.to_s
diff --git a/Library/Homebrew/system_config.rb b/Library/Homebrew/system_config.rb
index cc58ef1262..a019aa4de0 100644
--- a/Library/Homebrew/system_config.rb
+++ b/Library/Homebrew/system_config.rb
@@ -76,8 +76,11 @@ module SystemConfig
     def describe_clang
       return "N/A" if clang.null?
 
-      clang_build_info = clang_build.null? ? "(parse error)" : clang_build
-      "#{clang} build #{clang_build_info}"
+      if clang_build.null?
+        clang.to_s
+      else
+        "#{clang} build #{clang_build}"
+      end
     end
 
     def describe_path(path)