Add test case for expanding a macro defined in terms of another macro

Author: DougGregor

test/Macros/macro_expand_other.swift

@@ -0,0 +1,38 @@
+// Expanding macros that are defined in terms of other macros.
+
+// RUN: %empty-directory(%t)
+// RUN: %host-build-swift -swift-version 5 -emit-library -o %t/%target-library-name(MacroDefinition) -parse-as-library -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift -g -no-toolchain-stdlib-rpath
+
+// Diagnostics testing
+// RUN: %target-typecheck-verify-swift -swift-version 5 -enable-experimental-feature FreestandingMacros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -module-name MacroUser -DTEST_DIAGNOSTICS
+
+// Execution testing
+// RUN: %target-build-swift -swift-version 5 -enable-experimental-feature FreestandingMacros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -L %swift-host-lib-dir %s -o %t/main -module-name MacroUser
+// RUN: %target-run %t/main | %FileCheck %s
+// RUN: %target-codesign %t/main
+// REQUIRES: swift_swift_parser, executable_test
+
+@freestanding(expression) macro stringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
+
+@freestanding(expression) macro stringifySeven() -> (Int, String) = #stringify(7)
+
+@freestanding(expression) macro recurse(_: Bool) = #externalMacro(module: "MacroDefinition", type: "RecursiveMacro")
+
+@freestanding(expression) macro recurseThrough(_ value: Bool) = #recurse(value)
+
+func testFreestandingExpansionOfOther() {
+  // CHECK: ---testFreestandingExpansionOfOther
+  print("---testFreestandingExpansionOfOther")
+
+  // CHECK-NEXT: (7, "7")
+  print(#stringifySeven)
+
+  #recurseThrough(false)
+
+  #if TEST_DIAGNOSTICS
+#recurseThrough(true)
+  // expected-note@-1 2{{in expansion of macro 'recurseThrough' here}}
+  #endif
+}
+
+testFreestandingExpansionOfOther()