Update module aliasing terms in diagnostics and comments

s/underlying_name/real_name

rdar://110028578

Author: elsh

include/swift/AST/DiagnosticsFrontend.def

@@ -195,11 +195,11 @@ ERROR(error_empty_package_name,none,
 ERROR(error_stdlib_not_found,Fatal,
       "unable to load standard library for target '%0'", (StringRef))
 ERROR(error_module_alias_invalid_format,none,
-      "invalid module alias format \"%0\"; make sure to use the format '-module-alias alias_name=underlying_name'", (StringRef))
+      "invalid module alias format \"%0\"; make sure to use the format '-module-alias alias_name=real_name'", (StringRef))
 ERROR(error_module_alias_forbidden_name,none,
       "invalid module alias \"%0\"; make sure the alias differs from the module name, module ABI name, module link name, and a standard library name", (StringRef))
 ERROR(error_module_alias_duplicate,none,
-      "duplicate module alias; the name \"%0\" is already used for a module alias or an underlying name", (StringRef))
+      "duplicate module alias; the name \"%0\" is already used for an alias or a real name", (StringRef))
 
 ERROR(error_unable_to_load_supplementary_output_file_map, none,
       "unable to load supplementary output file map '%0': %1",

include/swift/Frontend/FrontendOptions.h

@@ -51,7 +51,7 @@ class FrontendOptions {
   /// An Objective-C header to import and make implicitly visible.
   std::string ImplicitObjCHeaderPath;
 
-  /// The map of aliases and underlying names of imported or referenced modules.
+  /// The map of aliases and real names of imported or referenced modules.
   llvm::StringMap<StringRef> ModuleAliasMap;
 
   /// The name of the module that the frontend is building.

include/swift/Option/Options.td

@@ -520,8 +520,8 @@ def module_name_EQ : Joined<["-"], "module-name=">, Flags<[FrontendOption]>,
 
 def module_alias : Separate<["-"], "module-alias">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,
-  MetaVarName<"<alias_name=underlying_name>">,
-  HelpText<"If a source file imports or references module <alias_name>, the <underlying_name> is used for the contents of the file">;
+  MetaVarName<"<alias_name=real_name>">,
+  HelpText<"If a source file imports or references module <alias_name>, the <real_name> is used for the contents of the file">;
 
 def module_link_name : Separate<["-"], "module-link-name">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -831,7 +831,7 @@ bool ModuleAliasesConverter::computeModuleAliases(std::vector<std::string> args,
 
     for (auto item: args) {
       auto str = StringRef(item);
-      // splits to an alias and the underlying name
+      // splits to an alias and its real name
       auto pair = str.split('=');
       auto lhs = pair.first;
       auto rhs = pair.second;
@@ -844,13 +844,13 @@ bool ModuleAliasesConverter::computeModuleAliases(std::vector<std::string> args,
         return false;
       }
 
-      // First, add the underlying name as a key to prevent it from being
+      // First, add the real name as a key to prevent it from being
       // used as an alias
       if (!options.ModuleAliasMap.insert({rhs, StringRef()}).second) {
         diags.diagnose(SourceLoc(), diag::error_module_alias_duplicate, rhs);
         return false;
       }
-      // Next, add the alias as a key and the underlying name as a value to the map
+      // Next, add the alias as a key and the real name as a value to the map
       auto underlyingName = options.ModuleAliasMap.find(rhs)->first();
       if (!options.ModuleAliasMap.insert({lhs, underlyingName}).second) {
         diags.diagnose(SourceLoc(), diag::error_module_alias_duplicate, lhs);

test/Frontend/module-alias-invalid-input.swift

@@ -8,13 +8,13 @@
 // RUN: %target-swift-frontend -emit-silgen -parse-as-library %s -module-name foo -module-alias Bar=Swift -verify
 
 // RUN: not %target-swift-frontend -emit-silgen -parse-as-library %s -module-name foo -module-alias bar=bar 2>&1 | %FileCheck -check-prefix=INVALID_MODULE_ALIAS2 %s
-// INVALID_MODULE_ALIAS2: error: duplicate module alias; the name "bar" is already used for a module alias or an underlying name
+// INVALID_MODULE_ALIAS2: error: duplicate module alias; the name "bar" is already used for an alias or a real name
 
 // RUN: not %target-swift-frontend -emit-silgen -parse-as-library %s -module-name foo -module-alias bar=baz -module-alias baz=cat 2>&1 | %FileCheck -check-prefix=INVALID_MODULE_ALIAS3 %s
-// INVALID_MODULE_ALIAS3: error: duplicate module alias; the name "baz" is already used for a module alias or an underlying name
+// INVALID_MODULE_ALIAS3: error: duplicate module alias; the name "baz" is already used for an alias or a real name
 
 // RUN: not %target-swift-frontend -emit-silgen -parse-as-library %s -module-name foo -module-alias bar 2>&1 | %FileCheck -check-prefix=INVALID_MODULE_ALIAS4 %s
-// INVALID_MODULE_ALIAS4: error: invalid module alias format "bar"; make sure to use the format '-module-alias alias_name=underlying_name'
+// INVALID_MODULE_ALIAS4: error: invalid module alias format "bar"; make sure to use the format '-module-alias alias_name=real_name'
 
 // RUN: not %target-swift-frontend -emit-silgen -parse-as-library %s -module-name foo -module-alias bar=c-a.t 2>&1 | %FileCheck -check-prefix=INVALID_MODULE_NAME %s
 // INVALID_MODULE_NAME: error: module name "c-a.t" is not a valid identifier