[TargetEnvironmentHeader] Properly sanitize configuration defines

Closes https://github.com/CocoaPods/CocoaPods/issues/3301.

CHANGELOG.md

@@ -6,11 +6,18 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
 
 ## Master
 
+##### Bug Fixes
+
 * Fix the resource script's handling of `.xcasset` files.  
   [sodas](https://github.com/sodastsai)
   [Tony Li](https://github.com/crazytonyli)
   [#3247](https://github.com/CocoaPods/CocoaPods/issues/3247)
 
+* Fix the sanitization of configuration names in the generated target
+  environment header.  
+  [Samuel Giddins](https://github.com/segiddins)
+  [#3301](https://github.com/CocoaPods/CocoaPods/issues/3301)
+
 
 ## 0.36.0
 

lib/cocoapods/generator/target_environment_header.rb

@@ -46,10 +46,12 @@ module Pod
         common_specs = common_specs(specs_by_configuration)
         common_specs.each { |spec| result << spec_defines(spec) }
 
+        c99ext_identifier_method = Target.new.method(:c99ext_identifier)
+
         specs_by_config = specs_scoped_by_configuration(common_specs, specs_by_configuration)
         specs_by_config.each do |config, specs|
           result << "// #{config} build configuration\n"
-          result << "#ifdef #{config.gsub(/[^a-zA-Z0-9_]/, '_').upcase}\n\n"
+          result << "#ifdef #{c99ext_identifier_method[config].upcase}\n\n"
           specs.each { |spec| result << spec_defines(spec, 1) }
           result << "#endif\n"
         end

spec/unit/generator/target_environment_header_spec.rb

@@ -74,9 +74,11 @@ describe Pod::Generator::TargetEnvironmentHeader do
       'Debug' => [],
       'build configuration copy' => [spec],
       'build-_config@copy' => [spec],
+      '1 - Develop' => [spec],
     }
     @gen = Pod::Generator::TargetEnvironmentHeader.new(specs_by_configuration)
     @gen.generate.should.include 'BUILD_CONFIGURATION_COPY'
     @gen.generate.should.include 'BUILD__CONFIG_COPY'
+    @gen.generate.should.include '_1___DEVELOP'
   end
 end