Document superenv HOMEBREW_CCFG flags

1 files changed, 15 insertions, 1 deletions

diff --git a/Library/Homebrew/superenv.rb b/Library/Homebrew/superenv.rb
index b15d40f6b..dfa6b2610 100644
--- a/Library/Homebrew/superenv.rb
+++ b/Library/Homebrew/superenv.rb
@@ -63,6 +63,20 @@ class << ENV
     ENV['CMAKE_LIBRARY_PATH'] = determine_cmake_library_path
     ENV['ACLOCAL_PATH'] = determine_aclocal_path
 
+    # The HOMEBREW_CCCFG ENV variable is used by the ENV/cc tool to control
+    # compiler flag stripping. It consists of a string of characters which act
+    # as flags. Some of these flags are mutually exclusive.
+    #
+    # u - A universal build was requested
+    # 3 - A 32-bit build was requested
+    # b - Installing from a bottle
+    # i - Installing from a bottle on Intel
+    # 6 - Installing from a bottle on 64-bit Intel
+    #
+    # On 10.8 and newer, these flags will also be present:
+    # s - apply fix for sed's Unicode support
+    # a - apply fix for apr-1-config path
+
     # Homebrew's apple-gcc42 will be outside the PATH in superenv,
     # so xcrun may not be able to find it
     if ENV['HOMEBREW_CC'] == 'gcc-4.2'
@@ -75,7 +89,7 @@ class << ENV
     append 'HOMEBREW_CCCFG', "u", ''
   end
 
-  # m32 on superenv does not add any flags. It prevents "-m32" from being erased.
+  # m32 on superenv does not add any CC flags. It prevents "-m32" from being erased.
   def m32
     append 'HOMEBREW_CCCFG', "3", ''
   end