Reorganize superenv include and library path setup

I found the dual use of CMAKE_*_PATH variables to make it difficult to
reason about this code. Now a separate set of variables are used to
communicate with the cc wrapper, and less work is performed in the
wrapper itself.

We no longer pass the SDK include path as a -isystem directory on
Xcode-only setups. Doing so is redundant with `--sysroot` and has other
side effects, namely changing the include path search order, which can
break compilation of some software (e.g. qemu).

On Xcode-only 10.9, we can additionally omit `--sysroot`, as the correct
paths are built into the tools.

A new variable, HOMEBREW_SYSROOT, is used to this information to the
wrapper. It will be unset on Xcode-only 10.9. HOMEBREW_SDKROOT will
continue to be set, as it is used for other things besides setting the
include search path.

1 files changed, 47 insertions, 21 deletions

diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index cb05ec964..0c6d10547 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -66,6 +66,15 @@ module Superenv
     self['CMAKE_LIBRARY_PATH'] = determine_cmake_library_path
     self['ACLOCAL_PATH'] = determine_aclocal_path
     self['M4'] = MacOS.locate("m4") if deps.include? "autoconf"
+    self["HOMEBREW_ISYSTEM_PATHS"] = determine_isystem_paths
+    self["HOMEBREW_INCLUDE_PATHS"] = determine_include_paths
+    self["HOMEBREW_LIBRARY_PATHS"] = determine_library_paths
+
+    # On 10.9 the developer tools honor the correct sysroot by default.
+    # On 10.7 and 10.8 we need to set it ourselves.
+    if MacOS::Xcode.without_clt? && MacOS.version <= "10.8"
+      self["HOMEBREW_SYSROOT"] = effective_sysroot
+    end
 
     # On 10.9, the tools in /usr/bin proxy to the active developer directory.
     # This means we can use them for any combination of CLT and Xcode.
@@ -100,6 +109,10 @@ module Superenv
     self["HOMEBREW_CXX"] = super
   end
 
+  def effective_sysroot
+    if MacOS::Xcode.without_clt? then MacOS.sdk_path.to_s else "" end
+  end
+
   def determine_cc
     cc = compiler
     COMPILER_SYMBOL_MAP.invert.fetch(cc, cc)
@@ -159,40 +172,53 @@ module Superenv
     paths.to_path_s
   end
 
-  def determine_cmake_prefix_path
-    paths = keg_only_deps.map{|dep| "#{HOMEBREW_PREFIX}/opt/#{dep}" }
-    paths << HOMEBREW_PREFIX.to_s # put ourselves ahead of everything else
-    paths << "#{MacOS.sdk_path}/usr" if MacOS::Xcode.without_clt?
+  def determine_isystem_paths
+    paths = []
+    paths << "#{HOMEBREW_PREFIX}/include"
+    paths << "#{effective_sysroot}/usr/include/libxml2" unless deps.include? "libxml2"
+    paths << "#{effective_sysroot}/usr/include/apache2" if MacOS::Xcode.without_clt?
+    paths << "#{effective_sysroot}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Headers"
+    paths << MacOS::X11.include.to_s << "#{MacOS::X11.include}/freetype2" if x11?
     paths.to_path_s
   end
 
-  def determine_cmake_frameworks_path
-    paths = deps.map{|dep| "#{HOMEBREW_PREFIX}/opt/#{dep}/Frameworks" }
-    paths << "#{MacOS.sdk_path}/System/Library/Frameworks" if MacOS::Xcode.without_clt?
+  def determine_include_paths
+    keg_only_deps.map { |dep| "#{HOMEBREW_PREFIX}/opt/#{dep}/include" }.to_path_s
+  end
+
+  def determine_library_paths
+    paths = keg_only_deps.map { |dep| "#{HOMEBREW_PREFIX}/opt/#{dep}/lib" }
+    paths << "#{HOMEBREW_PREFIX}/lib"
+    paths << "#{effective_sysroot}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries"
+    paths << MacOS::X11.lib.to_s if x11?
+    paths.to_path_s
+  end
+
+  def determine_cmake_prefix_path
+    paths = keg_only_deps.map { |dep| "#{HOMEBREW_PREFIX}/opt/#{dep}" }
+    paths << HOMEBREW_PREFIX.to_s
     paths.to_path_s
   end
 
   def determine_cmake_include_path
-    sdk = MacOS.sdk_path if MacOS::Xcode.without_clt?
     paths = []
-    paths << "#{sdk}/usr/include/libxml2" unless deps.include? 'libxml2'
-    paths << "#{sdk}/usr/include/apache2" if MacOS::Xcode.without_clt?
-    if x11?
-      paths << MacOS::X11.include << "#{MacOS::X11.include}/freetype2"
-    else
-      paths << "#{sdk}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Headers"
-    end
+    paths << "#{effective_sysroot}/usr/include/libxml2" unless deps.include? "libxml2"
+    paths << "#{effective_sysroot}/usr/include/apache2" if MacOS::Xcode.without_clt?
+    paths << "#{effective_sysroot}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Headers"
+    paths << MacOS::X11.include.to_s << "#{MacOS::X11.include}/freetype2" if x11?
     paths.to_path_s
   end
 
   def determine_cmake_library_path
-    sdk = MacOS.sdk_path if MacOS::Xcode.without_clt?
     paths = []
-    if x11?
-      paths << MacOS::X11.lib
-    else
-      paths << "#{sdk}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries"
-    end
+    paths << "#{effective_sysroot}/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries"
+    paths << MacOS::X11.lib.to_s if x11?
+    paths.to_path_s
+  end
+
+  def determine_cmake_frameworks_path
+    paths = deps.map { |dep| "#{HOMEBREW_PREFIX}/opt/#{dep}/Frameworks" }
+    paths << "#{effective_sysroot}/System/Library/Frameworks" if MacOS::Xcode.without_clt?
     paths.to_path_s
   end