Ensure that we lazily find macro-unique names in nominal type context

Author: DougGregor

lib/AST/NameLookup.cpp

@@ -1255,6 +1255,7 @@ class swift::MemberLookupTable : public ASTAllocated<swift::MemberLookupTable> {
   }
 
   bool isLazilyCompleteForMacroExpansion(DeclName name) const {
+    assert(!MacroDecl::isUniqueMacroName(name.getBaseName()));
     // If we've already expanded macros for a simple name, we must have expanded
     // all macros that produce names with the same base identifier.
     bool isBaseNameComplete = name.isCompoundName() &&
@@ -1264,6 +1265,7 @@ class swift::MemberLookupTable : public ASTAllocated<swift::MemberLookupTable> {
   }
 
   void markLazilyCompleteForMacroExpansion(DeclName name) {
+    assert(!MacroDecl::isUniqueMacroName(name.getBaseName()));
     LazilyCompleteNamesForMacroExpansion.insert(name);
   }
 
@@ -1521,6 +1523,17 @@ populateLookupTableEntryFromExtensions(ASTContext &ctx,
   }
 }
 
+/// Adjust the given name to make it a proper key for the lazy macro expansion
+/// cache, which maps all uniquely-generated names down to a single placeholder
+/// key.
+static DeclName adjustLazyMacroExpansionNameKey(
+    ASTContext &ctx, DeclName name) {
+  if (MacroDecl::isUniqueMacroName(name.getBaseName()))
+    return MacroDecl::getUniqueNamePlaceholder(ctx);
+
+  return name;
+}
+
 static void
 populateLookupTableEntryFromMacroExpansions(ASTContext &ctx,
                                             MemberLookupTable &table,
@@ -1756,9 +1769,11 @@ DirectLookupRequest::evaluate(Evaluator &evaluator,
     Table.markLazilyComplete(baseName);
   }
 
-  if (!Table.isLazilyCompleteForMacroExpansion(name)) {
-    populateLookupTableEntryFromMacroExpansions(ctx, Table, name, decl);
-    Table.markLazilyCompleteForMacroExpansion(name);
+  DeclName macroExpansionKey = adjustLazyMacroExpansionNameKey(ctx, name);
+  if (!Table.isLazilyCompleteForMacroExpansion(macroExpansionKey)) {
+    populateLookupTableEntryFromMacroExpansions(
+        ctx, Table, macroExpansionKey, decl);
+    Table.markLazilyCompleteForMacroExpansion(macroExpansionKey);
   }
 
   // Look for a declaration with this name.

test/Macros/Inputs/syntax_macro_definitions.swift

@@ -456,6 +456,8 @@ public struct AddMembers: MemberMacro {
     providingMembersOf decl: some DeclGroupSyntax,
     in context: some MacroExpansionContext
   ) throws -> [DeclSyntax] {
+    let uniqueClassName = context.createUniqueName("uniqueClass")
+
     let storageStruct: DeclSyntax =
       """
       struct Storage {}
@@ -481,7 +483,12 @@ public struct AddMembers: MemberMacro {
 
     let initDecl: DeclSyntax =
       """
-      init() {}
+      init() { _ = \(uniqueClassName)() }
+      """
+
+    let classDecl: DeclSyntax =
+      """
+      class \(uniqueClassName) { }
       """
 
     return [
@@ -490,6 +497,7 @@ public struct AddMembers: MemberMacro {
       instanceMethod,
       staticMethod,
       initDecl,
+      classDecl,
     ]
   }
 }

test/Macros/macro_expand_synthesized_members.swift

@@ -2,7 +2,7 @@
 // RUN: %target-build-swift -swift-version 5 -I %swift-host-lib-dir -L %swift-host-lib-dir -emit-library -o %t/%target-library-name(MacroDefinition) -module-name=MacroDefinition %S/Inputs/syntax_macro_definitions.swift -g -no-toolchain-stdlib-rpath
 // RUNx: %target-swift-frontend -dump-ast -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir %s -module-name MacroUser 2>&1 | %FileCheck --check-prefix CHECK-AST %s
 // RUN: %target-typecheck-verify-swift -swift-version 5 -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -module-name MacroUser -DTEST_DIAGNOSTICS -swift-version 5
-// RUN: %target-build-swift -swift-version 5 -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 -swift-version 5
+// RUN: %target-build-swift -g -swift-version 5 -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 -swift-version 5
 // RUN: %target-run %t/main | %FileCheck %s
 // REQUIRES: executable_test