Removing isSwiftVersion4, isSwiftVersion5. We'll need to come up with a better way to conditionalize code based on language version.

Author: Ewa Matejska

include/swift/AST/ASTContext.h

@@ -865,12 +865,6 @@ class ASTContext {
 
   /// Whether our effective Swift version is in the Swift 3 family
   bool isSwiftVersion3() const { return LangOpts.isSwiftVersion3(); }
-  
-  /// Whether our effective Swift version is in the Swift 4 family
-  bool isSwiftVersion4() const { return LangOpts.isSwiftVersion4(); }
-  
-  /// Whether our effective Swift version is in the Swift 5 family
-  bool isSwiftVersion5() const { return LangOpts.isSwiftVersion5(); }
 
 private:
   friend Decl;

include/swift/Basic/LangOptions.h

@@ -310,16 +310,6 @@ namespace swift {
     bool isSwiftVersion3() const {
       return EffectiveLanguageVersion.isVersion3();
     }
-      
-    /// Whether our effective Swift version is in the Swift 4 family
-    bool isSwiftVersion4() const {
-       return EffectiveLanguageVersion.isVersion4();
-    }
-      
-    /// Whether our effective Swift version is in the Swift 5 family
-    bool isSwiftVersion5() const {
-       return EffectiveLanguageVersion.isVersion5();
-    }
 
     /// Returns true if the given platform condition argument represents
     /// a supported target operating system.

include/swift/Basic/Version.h

@@ -109,12 +109,6 @@ class Version {
 
   /// Whether this version is in the Swift 3 family
   bool isVersion3() const { return !empty() && Components[0] == 3; }
-    
-  /// Whether this version is in the Swift 4 family
-  bool isVersion4() const { return !empty() && Components[0] == 4; }
-  
-  /// Whether this version is in the Swift 5 family
-  bool isVersion5() const { return !empty() && Components[0] == 5; }
 
   /// Return this Version struct with minor and sub-minor components stripped
   Version asMajorVersion() const;