Extract build-time stdlib check to a method

Library/Homebrew/build.rb

@@ -163,29 +163,7 @@ class Build
 
         begin
           f.install
-
-          keg = Keg.new(f.prefix)
-          # This first test includes executables because we still
-          # want to record the stdlib for something that installs no
-          # dylibs.
-          stdlibs = keg.detect_cxx_stdlibs
-          # This currently only tracks a single C++ stdlib per dep,
-          # though it's possible for different libs/executables in
-          # a given formula to link to different ones.
-          stdlib_in_use = CxxStdlib.create(stdlibs.first, ENV.compiler)
-          begin
-            stdlib_in_use.check_dependencies(f, deps)
-          rescue IncompatibleCxxStdlibs => e
-            opoo e.message
-          end
-
-          # This second check is recorded for checking dependencies,
-          # so executable are irrelevant at this point. If a piece
-          # of software installs an executable that links against libstdc++
-          # and dylibs against libc++, libc++-only dependencies can safely
-          # link against it.
-          stdlibs = keg.detect_cxx_stdlibs :skip_executables => true
-
+          stdlibs = detect_stdlibs
           Tab.create(f, ENV.compiler, stdlibs.first, f.build).write
         rescue Exception => e
           if ARGV.debug?
@@ -201,6 +179,30 @@ class Build
     end
   end
 
+  def detect_stdlibs
+    keg = Keg.new(f.prefix)
+    # This first test includes executables because we still
+    # want to record the stdlib for something that installs no
+    # dylibs.
+    stdlibs = keg.detect_cxx_stdlibs
+    # This currently only tracks a single C++ stdlib per dep,
+    # though it's possible for different libs/executables in
+    # a given formula to link to different ones.
+    stdlib_in_use = CxxStdlib.create(stdlibs.first, ENV.compiler)
+    begin
+      stdlib_in_use.check_dependencies(f, deps)
+    rescue IncompatibleCxxStdlibs => e
+      opoo e.message
+    end
+
+    # This second check is recorded for checking dependencies,
+    # so executable are irrelevant at this point. If a piece
+    # of software installs an executable that links against libstdc++
+    # and dylibs against libc++, libc++-only dependencies can safely
+    # link against it.
+    stdlibs = keg.detect_cxx_stdlibs :skip_executables => true
+  end
+
   def fixopt f
     path = if f.linked_keg.directory? and f.linked_keg.symlink?
       f.linked_keg.resolved_path