Fixes Homebrew/homebrew#14542; ocaml superenv issues

This patch removes most of the settings for CC, CXX etc. because we are trying to be minimal. Then we force the compiler to Homebrew's choice underneath in superenv. We however leave LD because we prefer that build-systems use the c-compiler for linking, it generally works better (copiously tested), however when the build-system explicitly calls ld, we respect that. This gets around the ocaml bug in question, since somehow clang was crashing during link, but the ld tool itself (which is kind of clang, kind of llvm-gcc) is okay with this.

Also moved the setting of O (so that cc-args are refurbished) into a make wrapper. Not sure if this matter much, but seems more consistent.

Library/ENV/4.3/cc

@@ -44,29 +44,29 @@ class Cmd
     end
   end
   def tool
-    case @cmd
-      when /gcc/ then 'gcc'
-      when /g\+\+/ then 'g++'
-    when 'clang', 'clang++'
-      @cmd
-    when 'ld', 'cpp', 'cc'
-      ENV['HOMEBREW_CC'].chuzzle or 'clang'
-    when 'c++'
-      case ENV['HOMEBREW_CC']
-        when /gcc/ then 'g++'
-        else 'clang++'
+    @tool ||= if @cmd.include? '++'
+      if ENV['HOMEBREW_CC'].chuzzle =~ /gcc/
+        'g++'
+      else
+        'clang++'
       end
+    elsif @cmd == 'ld'
+      'ld'
     else
-      abort "Unknown command: #{@cmd}"
+      ENV['HOMEBREW_CC'].chuzzle or 'clang'
     end
   end
   def args
-    args = if cccfg? 'O'
+    args = if cccfg? 'O' and tool != 'ld'
       refurbished_args
     else
       @args.dup
     end
-    args.unshift("--sysroot=#$sdkroot") if nclt?
+    if @cmd != 'ld'
+      args.unshift("--sysroot=#$sdkroot")
+    else
+      args.unshift($sdkroot).unshift("-syslibroot")
+    end if nclt?
     case mode
     when :cpp
       %w{-E} + cppflags + args
@@ -110,13 +110,7 @@ class Cmd
         args << arg
       end
     end
-
-    rms = @args - args
-    %w{CPPFLAGS LDFLAGS CXXFLAGS CFLAGS}.each do |flag|
-      unison = ENV[flag].split(' ') & rms
-      puts "Warning! #{unison*' '} removed from #{flag.upcase} by superenv" unless unison.empty?
-    end
-
+    make_fuss(args)
     args
   end
   def cflags
@@ -141,6 +135,20 @@ class Cmd
     # they override the system options.
     sys.to_flags('-isystem') + opt.to_flags('-I')
   end
+  def make_fuss args
+    dels = @args - args
+    if ENV['VERBOSE']
+      adds = args - @args
+      puts "brew: Superenv removed: #{dels*' '}" unless dels.empty?
+      puts "brew: Superenv added: #{adds*' '}" unless adds.empty?
+    else
+      %w{CPPFLAGS LDFLAGS CXXFLAGS CFLAGS}.each do |flag|
+        next unless ENV[flag]
+        flags = dels.select{|del| ENV[flag].include? del }.join(' ')
+        puts "brew: superenv removed `#{flags}' from #{flag}" unless flags.empty?
+      end
+    end
+  end
 end
 
 ####################################################################### sanity

Library/ENV/4.3/make

@@ -0,0 +1,3 @@
+#!/bin/sh
+export HOMEBREW_CCCFG="O$HOMEBREW_CCCFG"
+exec xcrun make "$@"

Library/Homebrew/formula.rb

@@ -470,8 +470,6 @@ protected
     removed_ENV_variables = case if args.empty? then cmd.split(' ').first else cmd end
     when "xcodebuild"
       ENV.remove_cc_etc
-    when /^make\b/
-      ENV.append 'HOMEBREW_CCCFG', "O", ''
     end
 
     if ARGV.verbose?
@@ -502,8 +500,6 @@ protected
 
   rescue
     raise BuildError.new(self, cmd, args, $?)
-  ensure
-    ENV['HOMEBREW_CCCFG'] = ENV['HOMEBREW_CCCFG'].delete('O') if ENV['HOMEBREW_CCCFG']
   end
 
 public

Library/Homebrew/superenv.rb

@@ -28,7 +28,7 @@ class << ENV
   alias_method :x11?, :x11
 
   def reset
-    %w{CC CXX LD CPP OBJC MAKE
+    %w{CC CXX CPP OBJC MAKE
       CFLAGS CXXFLAGS OBJCFLAGS OBJCXXFLAGS LDFLAGS CPPFLAGS
       MACOS_DEPLOYMENT_TARGET SDKROOT
       CMAKE_PREFIX_PATH CMAKE_INCLUDE_PATH CMAKE_FRAMEWORK_PATH}.
@@ -40,11 +40,7 @@ class << ENV
 
   def setup_build_environment
     reset
-    ENV['CC'] = 'cc'
-    ENV['CXX'] = 'c++'
-    ENV['LD'] = 'ld'
-    ENV['CPP'] = 'cpp'
-    ENV['MAKE'] = 'make'
+    ENV['LD'] = 'cc'
     ENV['MAKEFLAGS'] ||= "-j#{determine_make_jobs}"
     ENV['PATH'] = determine_path
     ENV['PKG_CONFIG_PATH'] = determine_pkg_config_path
@@ -184,16 +180,13 @@ class << ENV
   end
   alias_method :j1, :deparallelize
   def gcc
-    ENV['CC'] = "gcc"
-    ENV['CXX'] = "g++"
+    ENV['HOMEBREW_CC'] = "gcc"
   end
   def llvm
-    ENV['CC'] = "llvm-gcc"
-    ENV['CXX'] = "llvm-g++"
+    ENV['HOMEBREW_CC'] = "llvm-gcc"
   end
   def clang
-    ENV['CC'] = "clang"
-    ENV['CXX'] = "clang++"
+    ENV['HOMEBREW_CC'] = "clang"
   end
   def make_jobs
     ENV['MAKEFLAGS'] =~ /-\w*j(\d)+/