Merge pull request #16187 from niu541412/master

Fix TypeError when building from source with gcc compiler in some MacOS version

Library/Homebrew/extend/ENV/shared.rb

@@ -348,7 +348,7 @@ def fetch_compiler(value, source)
     COMPILER_SYMBOL_MAP.fetch(value) do |other|
       case other
       when GNU_GCC_REGEXP
-        other
+        other.to_sym
       else
         raise "Invalid value for #{source}: #{other}"
       end