Install: add BuildToolsError and BuildFlagsError

Add these new errors, and guards in formula installation and
cmd/{,un,re}install to match, move can_build? to the MacOS module,
flatten conditions, remove redundant can_build? check

reinstate removed (doctor) check

3 files changed, 28 insertions, 6 deletions

diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index 1ef1ca61a..ce9bf5291 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -38,6 +38,14 @@ module Homebrew
         end
       end
 
+      # if the user's flags will prevent bottle only-installations when no
+      # developer tools are available, we need to stop them early on
+      if !MacOS.can_build?
+        bf = ARGV.collect_build_flags
+
+        raise BuildFlagsError.new(bf) if !bf.empty?
+      end
+
       ARGV.formulae.each do |f|
         # head-only without --HEAD is an error
         if !ARGV.build_head? && f.stable.nil? && f.devel.nil?
@@ -129,6 +137,9 @@ module Homebrew
     # when one is no longer required
     checks = Checks.new
     %w[
+      check_for_unsupported_osx
+      check_for_bad_install_name_tool
+      check_for_installed_developer_tools
       check_xcode_license_approved
       check_for_osx_gcc_installer
     ].each do |check|
@@ -157,12 +168,7 @@ module Homebrew
   def perform_preinstall_checks
     check_ppc
     check_writable_install_location
-    if MacOS::Xcode.installed?
-      check_xcode
-    else
-      opoo "You have not installed Xcode."
-      puts "Bottles may install correctly, but builds will fail!"
-    end
+    check_xcode if MacOS::Xcode.installed?
     check_cellar
   end
 
diff --git a/Library/Homebrew/cmd/reinstall.rb b/Library/Homebrew/cmd/reinstall.rb
index bf49282ae..98941698a 100644
--- a/Library/Homebrew/cmd/reinstall.rb
+++ b/Library/Homebrew/cmd/reinstall.rb
@@ -2,6 +2,14 @@ require "formula_installer"
 
 module Homebrew
   def reinstall
+    if !MacOS.can_build?
+      bf = ARGV.collect_build_flags
+
+      if !bf.empty?
+        raise BuildFlagsError.new(bf)
+      end
+    end
+
     ARGV.resolved_formulae.each { |f| reinstall_formula(f) }
   end
 
diff --git a/Library/Homebrew/cmd/upgrade.rb b/Library/Homebrew/cmd/upgrade.rb
index 8ae231002..e8fc9c0f8 100644
--- a/Library/Homebrew/cmd/upgrade.rb
+++ b/Library/Homebrew/cmd/upgrade.rb
@@ -3,6 +3,14 @@ require "cmd/outdated"
 
 module Homebrew
   def upgrade
+    if !MacOS.can_build?
+      bf = ARGV.collect_build_flags
+
+      if !bf.empty?
+        raise BuildFlagsError.new(bf)
+      end
+    end
+
     Homebrew.perform_preinstall_checks
 
     if ARGV.named.empty?