[Macros] Make sure we get different discriminators for top-level macros

Thank you, Hamish, for the test case!

Author: DougGregor

test/Macros/Inputs/top_level_freestanding_other.swift

@@ -1,3 +1,15 @@
 #anonymousTypes { "hello2" }
 
 var globalVar = #stringify(1 + 1)
+var globalVar2 = { #stringify(1 + 1) }()
+
+@available(*, deprecated)
+func deprecated() -> Int { 0 }
+
+var globalVar3 = #stringify({ deprecated() })
+// expected-note@-1 2{{in expansion of macro 'stringify' here}}
+// expected-warning@-2{{'deprecated()' is deprecated}}
+
+var globalVar4 = #stringify({ deprecated() })
+// expected-note@-1 2{{in expansion of macro 'stringify' here}}
+// expected-warning@-2{{'deprecated()' is deprecated}}

test/Macros/top_level_freestanding.swift

@@ -7,6 +7,10 @@
 // Type check testing
 // RUN: %target-typecheck-verify-swift -swift-version 5 -enable-experimental-feature FreestandingMacros -parse-as-library -load-plugin-library %t/%target-library-name(MacroDefinition) -module-name MacroUser -DTEST_DIAGNOSTICS -swift-version 5  %S/Inputs/top_level_freestanding_other.swift
 
+// Check diagnostic buffer names
+// RUN: %target-swift-frontend -typecheck -swift-version 5 -enable-experimental-feature FreestandingMacros -parse-as-library -load-plugin-library %t/%target-library-name(MacroDefinition) -module-name MacroUser -DTEST_DIAGNOSTICS -swift-version 5 %s %S/Inputs/top_level_freestanding_other.swift 2> %t.diags
+// RUN: %FileCheck -check-prefix DIAG_BUFFERS %s < %t.diags
+
 // Execution testing
 // RUN: %target-build-swift -g -swift-version 5 -enable-experimental-feature FreestandingMacros -parse-as-library -load-plugin-library %t/%target-library-name(MacroDefinition) %s %S/Inputs/top_level_freestanding_other.swift -o %t/main -module-name MacroUser -swift-version 5
 // RUN: %target-codesign %t/main
@@ -66,3 +70,6 @@ func testArbitraryAtGlobal() {
 }
 
 @freestanding(expression) macro stringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
+
+// DIAG_BUFFERS: @__swiftmacro_9MacroUser9stringifyfMf1_{{.*}}warning: 'deprecated()' is deprecated
+// DIAG_BUFFERS: @__swiftmacro_9MacroUser9stringifyfMf2_{{.*}}warning: 'deprecated()' is deprecated