Add doc comments and tests for AST / SIL

Author: elsh

include/swift/AST/Module.h

@@ -194,6 +194,9 @@ class ModuleDecl
       current = clangModule;
     }
 
+    /// Returns the name of the current module.
+    /// Note that for a Swift module, it returns the current module's real (binary) name,
+    /// which can be different from the name if module aliasing was used (see -module-alias).
     StringRef operator*() const;
     ReverseFullNameIterator &operator++();
 

test/Frontend/module-alias-ast.swift

@@ -0,0 +1,37 @@
+/// Test AST with module aliasing.
+///
+/// Module 'Lib' imports module 'XLogging', and 'XLogging' is aliased 'AppleLogging'.
+
+// RUN: %empty-directory(%t)
+// RUN: %{python} %utils/split_file.py -o %t %s
+
+/// Create AppleLogging.swiftmodule by aliasing XLogging
+// RUN: %target-swift-frontend -module-name AppleLogging -module-alias XLogging=AppleLogging %t/FileLogging.swift -emit-module -emit-module-path %t/AppleLogging.swiftmodule
+// RUN: test -f %t/AppleLogging.swiftmodule
+
+/// Verify AST contains XLogging, not AppleLogging
+// RUN: %target-swift-frontend -dump-ast %t/FileLib.swift -module-alias XLogging=AppleLogging -I %t > %t/result-ast.output
+
+// RUN: %FileCheck %s -input-file %t/result-ast.output -check-prefix CHECK-AST
+// CHECK-AST: XLogging
+// RUN: not %FileCheck %s -input-file %t/result-ast.output -check-prefix CHECK-NOT-AST
+// CHECK-NOT-AST: AppleLogging
+
+
+// BEGIN FileLogging.swift
+public struct Logger {
+  public init() {}
+}
+public func setup() -> XLogging.Logger? {
+  return Logger()
+}
+
+// BEGIN FileLib.swift
+import XLogging
+
+public func start() -> XLogging.Logger? {
+  return XLogging.setup()
+}
+
+public func end(_ arg: XLogging.Logger) {
+}

test/Frontend/module-alias-sil.swift

@@ -0,0 +1,36 @@
+/// Test SIL with module aliasing.
+///
+/// Module 'Lib' imports module 'XLogging', and 'XLogging' is aliased 'AppleLogging'.
+
+// RUN: %empty-directory(%t)
+// RUN: %{python} %utils/split_file.py -o %t %s
+
+/// Create AppleLogging.swiftmodule by aliasing XLogging
+// RUN: %target-swift-frontend -module-name AppleLogging -module-alias XLogging=AppleLogging %t/FileLogging.swift -emit-module -emit-module-path %t/AppleLogging.swiftmodule
+// RUN: test -f %t/AppleLogging.swiftmodule
+
+/// Verify generated SIL contains AppleLogging, and XLogging only appears in import lines in the prologue
+// RUN: %target-swift-frontend -emit-sil %t/FileLib.swift -module-alias XLogging=AppleLogging -I %t > %t/result-sil.output
+// RUN: %FileCheck %s -input-file %t/result-sil.output -check-prefix CHECK-SIL
+// CHECK-SIL: import XLogging
+// CHECK-SIL: s12AppleLogging
+// RUN: not %FileCheck %s -input-file %t/result-sil.output -check-prefix CHECK-NOT-SIL
+// CHECK-NOT-SIL: s8XLogging
+
+// BEGIN FileLogging.swift
+public struct Logger {
+  public init() {}
+}
+public func setup() -> XLogging.Logger? {
+  return Logger()
+}
+
+// BEGIN FileLib.swift
+import XLogging
+
+public func start() -> XLogging.Logger? {
+  return XLogging.setup()
+}
+
+public func end(_ arg: XLogging.Logger) {
+}