Merge pull request #29660 from nkcsgexi/macro-guard

[PrintAsObjc] add macro guard against potential recursive definitions

Author: nkcsgexi

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -26,9 +26,13 @@
 
 using namespace swift;
 
-static void writePrologue(raw_ostream &out, ASTContext &ctx) {
+static void writePrologue(raw_ostream &out, ASTContext &ctx,
+                          StringRef macroGuard) {
   out << "// Generated by " << version::getSwiftFullVersion(
     ctx.LangOpts.EffectiveLanguageVersion) << "\n"
+         // Guard against recursive definition.
+         << "#ifndef " << macroGuard << "\n"
+         << "#define " << macroGuard << "\n"
          "#pragma clang diagnostic push\n"
          "#pragma clang diagnostic ignored \"-Wgcc-compat\"\n"
          "\n"
@@ -373,7 +377,9 @@ static void writeEpilogue(raw_ostream &os) {
       "#if __has_attribute(external_source_symbol)\n"
       "# pragma clang attribute pop\n"
       "#endif\n"
-      "#pragma clang diagnostic pop\n";
+      "#pragma clang diagnostic pop\n"
+      // For the macro guard against recursive definition
+      "#endif\n";
 }
 
 bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
@@ -385,8 +391,8 @@ bool swift::printAsObjC(raw_ostream &os, ModuleDecl *M,
   std::string moduleContentsBuf;
   llvm::raw_string_ostream moduleContents{moduleContentsBuf};
   printModuleContentsAsObjC(moduleContents, imports, *M, minRequiredAccess);
-
-  writePrologue(os, M->getASTContext());
+  std::string macroGuard = (llvm::Twine(M->getNameStr().upper()) + "_SWIFT_H").str();
+  writePrologue(os, M->getASTContext(), macroGuard);
   writeImports(os, imports, *M, bridgingHeader);
   writePostImportPrologue(os, *M);
   os << moduleContents.str();

test/PrintAsObjC/Inputs/comments-expected-output.h

@@ -428,3 +428,4 @@ SWIFT_CLASS("_TtC8comments13UnorderedList")
 # pragma clang attribute pop
 #endif
 #pragma clang diagnostic pop
+#endif

test/PrintAsObjC/accessibility.swift

@@ -21,6 +21,9 @@
 
 // REQUIRES: objc_interop
 
+// CHECK: #ifndef ACCESSIBILITY_SWIFT_H
+// CHECK-NEXT: #define ACCESSIBILITY_SWIFT_H
+
 // CHECK-LABEL: @interface A_Public{{$}}
 // CHECK-INTERNAL-NEXT: init
 // CHECK-NEXT: @end