ICU4C should leave the keg-only status.

Library/Formula/boost.rb

@@ -71,10 +71,7 @@ def install
     # we specify libdir too because the script is apparently broken
     bargs = ["--prefix=#{prefix}", "--libdir=#{lib}"]
 
-    if build.include? 'with-icu'
-      icu4c_prefix = Formula.factory('icu4c').opt_prefix
-      bargs << "--with-icu=#{icu4c_prefix}"
-    else
+    unless build.include? 'with-icu'
       bargs << '--without-icu'
     end
 

Library/Formula/boost149.rb

@@ -49,10 +49,7 @@ def install
     # we specify libdir too because the script is apparently broken
     bargs = ["--prefix=#{prefix}", "--libdir=#{lib}"]
 
-    if build.include? 'with-icu'
-      icu4c_prefix = Formula.factory('icu4c').opt_prefix
-      bargs << "--with-icu=#{icu4c_prefix}"
-    else
+    unless build.include? 'with-icu'
       bargs << '--without-icu'
     end
 

Library/Formula/dwdiff.rb

@@ -10,9 +10,8 @@ class Dwdiff < Formula
 
   def install
     gettext = Formula.factory('gettext')
-    icu4c = Formula.factory('icu4c')
-    ENV.append "CFLAGS", "-I#{gettext.include} -I#{icu4c.include}"
-    ENV.append "LDFLAGS", "-L#{gettext.lib} -L#{icu4c.lib}"
+    ENV.append "CFLAGS", "-I#{gettext.include}"
+    ENV.append "LDFLAGS", "-L#{gettext.lib}"
     system "./configure", "--prefix=#{prefix}"
     system "make install"
 

Library/Formula/mapnik.rb

@@ -25,7 +25,6 @@ class Mapnik < Formula
   end
 
   def install
-    icu = Formula.factory("icu4c")
     # mapnik compiles can take ~1.5 GB per job for some .cpp files
     # so lets be cautious by limiting to CPUS/2
     jobs = ENV.make_jobs
@@ -40,8 +39,6 @@ def install
            "CXX=\"#{ENV.cxx}\"",
            "JOBS=#{jobs}",
            "PREFIX=#{prefix}",
-           "ICU_INCLUDES=#{icu.include}",
-           "ICU_LIBS=#{icu.lib}",
            "PYTHON_PREFIX=#{prefix}"  # Install to Homebrew's site-packages
     system "python",
            "scons/scons.py",

Library/Formula/yaz.rb

@@ -8,6 +8,17 @@ class Yaz < Formula
   depends_on 'pkg-config' => :build
 
   def install
+    # Both libxml2 2.7.3 and icu are defined the same data type `UChar'.
+    ENV.append_to_cflags "-Wno-typedef-redefinition" if ENV.compiler == :clang
+
+    if (ENV.compiler == :gcc or ENV.compiler == :llvm) and build.include? "env=std"
+      opoo <<-EOS.undent
+        GCC and LLVM-GCC can't build with icu and system's libxml together.
+        If you have request about this and have Clang, you can compile it with:
+          brew install yaz --env=std --use-clang
+      EOS
+    end
+
     system "./configure", "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
                           "--with-xml2"