diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1780,25 +1780,26 @@
       StringRef ArgStr =
           Args.hasArg(OPT_interface_stub_version_EQ)
               ? Args.getLastArgValue(OPT_interface_stub_version_EQ)
-              : "experimental-ifs-v1";
+              : "experimental-ifs-v2";
       if (ArgStr == "experimental-yaml-elf-v1" ||
+          ArgStr ==  "experimental-ifs-v1" ||
           ArgStr == "experimental-tapi-elf-v1") {
         std::string ErrorMessage =
             "Invalid interface stub format: " + ArgStr.str() +
             " is deprecated.";
         Diags.Report(diag::err_drv_invalid_value)
             << "Must specify a valid interface stub format type, ie: "
-               "-interface-stub-version=experimental-ifs-v1"
+               "-interface-stub-version=experimental-ifs-v2"
             << ErrorMessage;
-      } else if (ArgStr != "experimental-ifs-v1") {
+      } else if (!ArgStr.startswith("experimental-ifs-")) {
         std::string ErrorMessage =
             "Invalid interface stub format: " + ArgStr.str() + ".";
         Diags.Report(diag::err_drv_invalid_value)
             << "Must specify a valid interface stub format type, ie: "
-               "-interface-stub-version=experimental-ifs-v1"
+               "-interface-stub-version=experimental-ifs-v2"
             << ErrorMessage;
       } else {
-        Opts.ProgramAction = frontend::GenerateInterfaceIfsExpV1;
+        Opts.ProgramAction = frontend::GenerateInterfaceStubs;
       }
       break;
     }
@@ -3367,7 +3368,7 @@
   case frontend::GenerateModuleInterface:
   case frontend::GenerateHeaderModule:
   case frontend::GeneratePCH:
-  case frontend::GenerateInterfaceIfsExpV1:
+  case frontend::GenerateInterfaceStubs:
   case frontend::ParseSyntaxOnly:
   case frontend::ModuleFileInfo:
   case frontend::VerifyPCH:
diff --git a/clang/lib/Frontend/InterfaceStubFunctionsConsumer.cpp b/clang/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
--- a/clang/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
+++ b/clang/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
@@ -290,7 +290,7 @@
                              const ASTContext &context, StringRef Format,
                              raw_ostream &OS) -> void {
       OS << "--- !" << Format << "\n";
-      OS << "IfsVersion: 1.0\n";
+      OS << "IfsVersion: 2.0\n";
       OS << "Triple: " << T.str() << "\n";
       OS << "ObjectFileFormat: "
          << "ELF"
@@ -299,11 +299,11 @@
       for (const auto &E : Symbols) {
         const MangledSymbol &Symbol = E.second;
         for (auto Name : Symbol.Names) {
-          OS << "  \""
+          OS << "  - { Name: \""
              << (Symbol.ParentName.empty() || Instance.getLangOpts().CPlusPlus
                      ? ""
                      : (Symbol.ParentName + "."))
-             << Name << "\" : { Type: ";
+             << Name << "\", Type: ";
           switch (Symbol.Type) {
           default:
             llvm_unreachable(
@@ -330,15 +330,15 @@
       OS.flush();
     };
 
-    assert(Format == "experimental-ifs-v1" && "Unexpected IFS Format.");
+    assert(Format == "experimental-ifs-v2" && "Unexpected IFS Format.");
     writeIfsV1(Instance.getTarget().getTriple(), Symbols, context, Format, *OS);
   }
 };
 } // namespace
 
 std::unique_ptr<ASTConsumer>
-GenerateInterfaceIfsExpV1Action::CreateASTConsumer(CompilerInstance &CI,
-                                                   StringRef InFile) {
+GenerateInterfaceStubsAction::CreateASTConsumer(CompilerInstance &CI,
+                                                StringRef InFile) {
   return std::make_unique<InterfaceStubFunctionsConsumer>(
-      CI, InFile, "experimental-ifs-v1");
+      CI, InFile, "experimental-ifs-v2");
 }
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -65,8 +65,8 @@
   case GenerateHeaderModule:
     return std::make_unique<GenerateHeaderModuleAction>();
   case GeneratePCH:            return std::make_unique<GeneratePCHAction>();
-  case GenerateInterfaceIfsExpV1:
-    return std::make_unique<GenerateInterfaceIfsExpV1Action>();
+  case GenerateInterfaceStubs:
+    return std::make_unique<GenerateInterfaceStubsAction>();
   case InitOnly:               return std::make_unique<InitOnlyAction>();
   case ParseSyntaxOnly:        return std::make_unique<SyntaxOnlyAction>();
   case ModuleFileInfo:         return std::make_unique<DumpModuleInfoAction>();
diff --git a/clang/test/InterfaceStubs/bad-format.cpp b/clang/test/InterfaceStubs/bad-format.cpp
--- a/clang/test/InterfaceStubs/bad-format.cpp
+++ b/clang/test/InterfaceStubs/bad-format.cpp
@@ -21,16 +21,16 @@
 // CHECK: error: invalid value
 // CHECK: 'Invalid interface stub format: bad-format.' in 'Must specify a
 // CHECK: valid interface stub format type, ie:
-// CHECK: -interface-stub-version=experimental-ifs-v1'
+// CHECK: -interface-stub-version=experimental-ifs-v2'
 
 // CHECK-TAPI-DEPRECATED: error: invalid value
 // CHECK-TAPI-DEPRECATED: 'Invalid interface stub format:
 // CHECK-TAPI-DEPRECATED: experimental-tapi-elf-v1 is deprecated.' in 'Must
 // CHECK-TAPI-DEPRECATED: specify a valid interface stub format type, ie:
-// CHECK-TAPI-DEPRECATED: -interface-stub-version=experimental-ifs-v1'
+// CHECK-TAPI-DEPRECATED: -interface-stub-version=experimental-ifs-v2'
 
 // CHECK-YAML-DEPRECATED: error: invalid value
 // CHECK-YAML-DEPRECATED: 'Invalid interface stub format:
 // CHECK-YAML-DEPRECATED: experimental-yaml-elf-v1 is deprecated.' in 'Must
 // CHECK-YAML-DEPRECATED: specify a valid interface stub format type, ie:
-// CHECK-YAML-DEPRECATED: -interface-stub-version=experimental-ifs-v1'
+// CHECK-YAML-DEPRECATED: -interface-stub-version=experimental-ifs-v2'
diff --git a/clang/test/InterfaceStubs/blocks.c b/clang/test/InterfaceStubs/blocks.c
--- a/clang/test/InterfaceStubs/blocks.c
+++ b/clang/test/InterfaceStubs/blocks.c
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -emit-interface-stubs -fblocks -o - %s | FileCheck %s
 
-// CHECK: --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK: --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/class-template-partial-specialization.cpp b/clang/test/InterfaceStubs/class-template-partial-specialization.cpp
--- a/clang/test/InterfaceStubs/class-template-partial-specialization.cpp
+++ b/clang/test/InterfaceStubs/class-template-partial-specialization.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/conflict-type.ifs b/clang/test/InterfaceStubs/conflict-type.ifs
--- a/clang/test/InterfaceStubs/conflict-type.ifs
+++ b/clang/test/InterfaceStubs/conflict-type.ifs
@@ -7,10 +7,10 @@
 # CHECK-IFS-NEXT: Filename:
 # CHECK-IFS-NEXT: Type Values: Object Func
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a: { Type: Object, Size: 1 }
+  - { Name: a, Type: Object, Size: 1 }
 ...
diff --git a/clang/test/InterfaceStubs/constructor-using-shadow.cpp b/clang/test/InterfaceStubs/constructor-using-shadow.cpp
--- a/clang/test/InterfaceStubs/constructor-using-shadow.cpp
+++ b/clang/test/InterfaceStubs/constructor-using-shadow.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/cxx-conversion.cpp b/clang/test/InterfaceStubs/cxx-conversion.cpp
--- a/clang/test/InterfaceStubs/cxx-conversion.cpp
+++ b/clang/test/InterfaceStubs/cxx-conversion.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/cxxdeduction-guide.cpp b/clang/test/InterfaceStubs/cxxdeduction-guide.cpp
--- a/clang/test/InterfaceStubs/cxxdeduction-guide.cpp
+++ b/clang/test/InterfaceStubs/cxxdeduction-guide.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs -std=c++17 %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/driver-test3.c b/clang/test/InterfaceStubs/driver-test3.c
--- a/clang/test/InterfaceStubs/driver-test3.c
+++ b/clang/test/InterfaceStubs/driver-test3.c
@@ -8,12 +8,12 @@
 
 // CHECK-OBJ: bar
 
-// CHECK-IFS: --- !experimental-ifs-v1
+// CHECK-IFS: --- !experimental-ifs-v2
 // CHECK-IFS-NEXT: IfsVersion:
 // CHECK-IFS-NEXT: Triple:
 // CHECK-IFS-NEXT: ObjectFileFormat:
 // CHECK-IFS-NEXT: Symbols:
-// CHECK-IFS-NEXT:   "bar" : { Type: Func }
+// CHECK-IFS-NEXT:   - { Name: "bar", Type: Func }
 // CHECK-IFS-NEXT: ...
 
 int bar(int a) { return a; }
diff --git a/clang/test/InterfaceStubs/empty.c b/clang/test/InterfaceStubs/empty.c
new file mode 100644
--- /dev/null
+++ b/clang/test/InterfaceStubs/empty.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
+
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
+// CHECK-NEXT: Triple:
+// CHECK-NEXT: ObjectFileFormat:
+// CHECK-NEXT: Symbols:
+// CHECK-NEXT: ...
diff --git a/clang/test/InterfaceStubs/func.ifs b/clang/test/InterfaceStubs/func.ifs
--- a/clang/test/InterfaceStubs/func.ifs
+++ b/clang/test/InterfaceStubs/func.ifs
@@ -7,13 +7,13 @@
 # RUN: %clang -emit-interface-stubs -o - %s %s -emit-merged-ifs | \
 # RUN: FileCheck %s --check-prefixes=CHECK-MERGE-IFS
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion:      1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple:          x86_64-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-DAG:   a:               { Type: Func }
-# CHECK-IFS-DAG:   b:               { Type: Object, Size: 4 }
+# CHECK-IFS-DAG:   - { Name: a, Type: Func }
+# CHECK-IFS-DAG:   - { Name: b, Type: Object, Size: 4 }
 # CHECK-IFS: ...
 
 # CHECK-ELF: ELF Header:
@@ -23,18 +23,18 @@
 # CHECK-ELF:   OBJECT  GLOBAL DEFAULT  1 b
 
 # Here we are testing to see if two identical symbols will merge.
-# CHECK-MERGE-IFS: --- !experimental-ifs-v1
-# CHECK-MERGE-IFS-NEXT: IfsVersion:      1.0
+# CHECK-MERGE-IFS: --- !experimental-ifs-v2
+# CHECK-MERGE-IFS-NEXT: IfsVersion: 2.0
 # CHECK-MERGE-IFS-NEXT: Triple:          x86_64-linux-gnu
 # CHECK-MERGE-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-MERGE-IFS-NEXT: Symbols:
-# CHECK-MERGE-IFS-NEXT:   a:               { Type: Func }
+# CHECK-MERGE-IFS-NEXT:   - { Name: a, Type: Func }
 # CHECK-MERGE-IFS-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a: { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/clang/test/InterfaceStubs/hidden-class-inheritance.cpp b/clang/test/InterfaceStubs/hidden-class-inheritance.cpp
--- a/clang/test/InterfaceStubs/hidden-class-inheritance.cpp
+++ b/clang/test/InterfaceStubs/hidden-class-inheritance.cpp
@@ -14,7 +14,7 @@
 // RUN: -DPARENT_METHOD_VISIBILITY="" -DCHILD_METHOD_VISIBILITY="" %s | \
 // RUN: FileCheck -check-prefix=CHECK-HP %s
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -o - -emit-interface-stubs \
-// RUN: -interface-stub-version=experimental-ifs-v1 \
+// RUN: -interface-stub-version=experimental-ifs-v2 \
 // RUN: -DPARENT_CLASS_VISIBILITY=HIDDEN -DCHILD_CLASS_VISIBILITY="" \
 // RUN: -DPARENT_METHOD_VISIBILITY="" -DCHILD_METHOD_VISIBILITY="" %s | \
 // RUN: FileCheck -check-prefix=CHECK-HP2 %s
diff --git a/clang/test/InterfaceStubs/indirect-field-decl.cpp b/clang/test/InterfaceStubs/indirect-field-decl.cpp
--- a/clang/test/InterfaceStubs/indirect-field-decl.cpp
+++ b/clang/test/InterfaceStubs/indirect-field-decl.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/inline.c b/clang/test/InterfaceStubs/inline.c
--- a/clang/test/InterfaceStubs/inline.c
+++ b/clang/test/InterfaceStubs/inline.c
@@ -55,8 +55,8 @@
 // RUN: -c -std=gnu89 -xc %s | llvm-nm - 2>&1 | \
 // RUN: FileCheck -check-prefix=CHECK-SYMBOLS %s
 
-// CHECK-TAPI-DAG: foo" : { Type: Func }
-// CHECK-TAPI-DAG: foo.var" : { Type: Object, Size: 4 }
+// CHECK-TAPI-DAG: foo", Type: Func }
+// CHECK-TAPI-DAG: foo.var",  Type: Object, Size: 4 }
 // CHECK-SYMBOLS-DAG: foo
 // CHECK-SYMBOLS-DAG: foo.var
 #include "inline.h"
diff --git a/clang/test/InterfaceStubs/lambda.cpp b/clang/test/InterfaceStubs/lambda.cpp
--- a/clang/test/InterfaceStubs/lambda.cpp
+++ b/clang/test/InterfaceStubs/lambda.cpp
@@ -1,11 +1,11 @@
 // RUN: %clang_cc1 -triple %itanium_abi_triple -emit-interface-stubs -o - %s \
 // RUN:     | FileCheck %s
 
-// CHECK: --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK: --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
-// CHECK-NEXT:   f" : { Type: Object, Size: 1 }
+// CHECK-NEXT:   f", Type: Object, Size: 1 }
 // CHECK-NEXT: ...
 auto f = [](void* data) { int i; };
diff --git a/clang/test/InterfaceStubs/namespace-alias.cpp b/clang/test/InterfaceStubs/namespace-alias.cpp
--- a/clang/test/InterfaceStubs/namespace-alias.cpp
+++ b/clang/test/InterfaceStubs/namespace-alias.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/namespace.cpp b/clang/test/InterfaceStubs/namespace.cpp
--- a/clang/test/InterfaceStubs/namespace.cpp
+++ b/clang/test/InterfaceStubs/namespace.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/non-type-template-parm-decl.cpp b/clang/test/InterfaceStubs/non-type-template-parm-decl.cpp
--- a/clang/test/InterfaceStubs/non-type-template-parm-decl.cpp
+++ b/clang/test/InterfaceStubs/non-type-template-parm-decl.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/object.c b/clang/test/InterfaceStubs/object.c
--- a/clang/test/InterfaceStubs/object.c
+++ b/clang/test/InterfaceStubs/object.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -fvisibility default -o - -emit-interface-stubs %s | FileCheck -check-prefix=CHECK-TAPI %s
 // RUN: %clang -fvisibility=default -c -o - %s | llvm-nm - 2>&1 | FileCheck -check-prefix=CHECK-SYMBOLS %s
 
-// CHECK-TAPI: data" : { Type: Object, Size: 4 }
+// CHECK-TAPI: data", Type: Object, Size: 4 }
 // CHECK-SYMBOLS: data
 int data = 42;
diff --git a/clang/test/InterfaceStubs/object.ifs b/clang/test/InterfaceStubs/object.ifs
--- a/clang/test/InterfaceStubs/object.ifs
+++ b/clang/test/InterfaceStubs/object.ifs
@@ -4,12 +4,12 @@
 # RUN: %clang -emit-interface-stubs -o - %s | llvm-readelf --all | \
 # RUN: FileCheck %s --check-prefixes=CHECK-ELF
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion:      1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple: x86_64-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-NEXT:   b:               { Type: Object, Size: 4 }
+# CHECK-IFS-NEXT:   - { Name: b, Type: Object, Size: 4 }
 # CHECK-IFS-NEXT: ...
 
 # CHECK-ELF: ELF Header:
@@ -19,10 +19,10 @@
 # CHECK-ELF-NOT:   FUNC    GLOBAL DEFAULT  1 a
 # CHECK-ELF:   OBJECT  GLOBAL DEFAULT  1 b
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  b: { Type: Object, Size: 4 }
+  - { Name: b, Type: Object, Size: 4 }
 ...
diff --git a/clang/test/InterfaceStubs/ppc.cpp b/clang/test/InterfaceStubs/ppc.cpp
--- a/clang/test/InterfaceStubs/ppc.cpp
+++ b/clang/test/InterfaceStubs/ppc.cpp
@@ -4,11 +4,11 @@
 // RUN:   -emit-interface-stubs -emit-merged-ifs -S | \
 // RUN: FileCheck -check-prefix=CHECK-IFS %s
 
- // CHECK-IFS: --- !experimental-ifs-v1
- // CHECK-IFS: IfsVersion:      1.0
+ // CHECK-IFS: --- !experimental-ifs-v2
+ // CHECK-IFS: IfsVersion: 2.0
  // CHECK-IFS: Triple: powerpc64le
  // CHECK-IFS: Symbols:
- // CHECK-IFS:   _Z8helloPPCv: { Type: Func }
+ // CHECK-IFS:   - { Name: _Z8helloPPCv, Type: Func }
  // CHECK-IFS: ...
 
 int helloPPC();
diff --git a/clang/test/InterfaceStubs/template-constexpr.cpp b/clang/test/InterfaceStubs/template-constexpr.cpp
--- a/clang/test/InterfaceStubs/template-constexpr.cpp
+++ b/clang/test/InterfaceStubs/template-constexpr.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/template-namespace-function.cpp b/clang/test/InterfaceStubs/template-namespace-function.cpp
--- a/clang/test/InterfaceStubs/template-namespace-function.cpp
+++ b/clang/test/InterfaceStubs/template-namespace-function.cpp
@@ -6,10 +6,10 @@
 // RUN: FileCheck -check-prefix=CHECK-SYMBOLS %s
 
 // CHECK: Symbols:
-// CHECK-DAG:  "_ZN3qux3barEii" : { Type: Func }
-// CHECK-DAG:  "_ZN3baz3addIiEET_S1_S1_" : { Type: Func }
-// CHECK-DAG:  "_Z4fbarff" : { Type: Func }
-// CHECK-DAG:  "_ZN3baz3addIfEET_S1_S1_" : { Type: Func }
+// CHECK-DAG:  - { Name: "_ZN3qux3barEii", Type: Func }
+// CHECK-DAG:  - { Name: "_ZN3baz3addIiEET_S1_S1_",  Type: Func }
+// CHECK-DAG:  - { Name: "_Z4fbarff", Type: Func }
+// CHECK-DAG:  - { Name: "_ZN3baz3addIfEET_S1_S1_", Type: Func }
 
 // Same symbols just different order.
 // CHECK-SYMBOLS-DAG:  _Z4fbarff
diff --git a/clang/test/InterfaceStubs/template-template-parm-decl.cpp b/clang/test/InterfaceStubs/template-template-parm-decl.cpp
--- a/clang/test/InterfaceStubs/template-template-parm-decl.cpp
+++ b/clang/test/InterfaceStubs/template-template-parm-decl.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/trycatch.cpp b/clang/test/InterfaceStubs/trycatch.cpp
--- a/clang/test/InterfaceStubs/trycatch.cpp
+++ b/clang/test/InterfaceStubs/trycatch.cpp
@@ -3,12 +3,12 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fcxx-exceptions -o - -emit-interface-stubs %s | FileCheck %s
 
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple: x86_64-unknown-linux-gnu
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
-// CHECK-NEXT: "_Z1fv" : { Type: Func }
+// CHECK-NEXT: - { Name: "_Z1fv", Type: Func }
 // CHECK-NEXT: ...
 
 class C5 {};
diff --git a/clang/test/InterfaceStubs/unresolved-using-typename.cpp b/clang/test/InterfaceStubs/unresolved-using-typename.cpp
--- a/clang/test/InterfaceStubs/unresolved-using-typename.cpp
+++ b/clang/test/InterfaceStubs/unresolved-using-typename.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/usings.cpp b/clang/test/InterfaceStubs/usings.cpp
--- a/clang/test/InterfaceStubs/usings.cpp
+++ b/clang/test/InterfaceStubs/usings.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple:
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
diff --git a/clang/test/InterfaceStubs/var-template-specialization-decl.cpp b/clang/test/InterfaceStubs/var-template-specialization-decl.cpp
--- a/clang/test/InterfaceStubs/var-template-specialization-decl.cpp
+++ b/clang/test/InterfaceStubs/var-template-specialization-decl.cpp
@@ -1,12 +1,12 @@
 // REQUIRES: x86-registered-target
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -o - -emit-interface-stubs %s | FileCheck %s
 
-// CHECK:      --- !experimental-ifs-v1
-// CHECK-NEXT: IfsVersion: 1.0
+// CHECK:      --- !experimental-ifs-v2
+// CHECK-NEXT: IfsVersion: 2.0
 // CHECK-NEXT: Triple: x86_64-unknown-linux-gnu
 // CHECK-NEXT: ObjectFileFormat: ELF
 // CHECK-NEXT: Symbols:
-// CHECK-NEXT: "a" : { Type: Object, Size: 4 }
+// CHECK-NEXT: - { Name: "a", Type: Object, Size: 4 }
 // CHECK-NEXT: ...
 
 template<typename T, T v> struct S9 {
diff --git a/clang/test/InterfaceStubs/weak.cpp b/clang/test/InterfaceStubs/weak.cpp
--- a/clang/test/InterfaceStubs/weak.cpp
+++ b/clang/test/InterfaceStubs/weak.cpp
@@ -1,14 +1,14 @@
 // REQUIRES: x86-registered-target
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -o - -emit-interface-stubs \
-// RUN: -interface-stub-version=experimental-ifs-v1 %s | \
+// RUN: -interface-stub-version=experimental-ifs-v2 %s | \
 // RUN: FileCheck %s
 
 // RUN: %clang -target x86_64-unknown-linux-gnu -o - -c %s | llvm-nm - 2>&1 | \
 // RUN: FileCheck -check-prefix=CHECK-SYMBOLS %s
 
 // CHECK: Symbols:
-// CHECK-DAG:  "_Z8weakFuncv" : { Type: Func, Weak: true }
-// CHECK-DAG:  "_Z10strongFuncv" : { Type: Func }
+// CHECK-DAG:  - { Name: "_Z8weakFuncv", Type: Func, Weak: true }
+// CHECK-DAG:  - { Name: "_Z10strongFuncv", Type: Func }
 
 // CHECK-SYMBOLS-DAG: _Z10strongFuncv
 // CHECK-SYMBOLS-DAG: _Z8weakFuncv
diff --git a/clang/test/InterfaceStubs/windows.cpp b/clang/test/InterfaceStubs/windows.cpp
--- a/clang/test/InterfaceStubs/windows.cpp
+++ b/clang/test/InterfaceStubs/windows.cpp
@@ -6,11 +6,11 @@
 // CHECK-CC1: Symbols:
 // CHECK-CC1-NEXT: ?helloWindowsMsvc@@YAHXZ
 
- // CHECK-IFS: --- !experimental-ifs-v1
- // CHECK-IFS: IfsVersion:      1.0
+ // CHECK-IFS: --- !experimental-ifs-v2
+ // CHECK-IFS: IfsVersion: 2.0
  // CHECK-IFS: Triple:
  // CHECK-IFS: Symbols:
- // CHECK-IFS:   ?helloWindowsMsvc@@YAHXZ: { Type: Func }
+ // CHECK-IFS:   - { Name: '?helloWindowsMsvc@@YAHXZ', Type: Func }
  // CHECK-IFS: ...
 
 int helloWindowsMsvc();
diff --git a/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-size.ifs b/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-size.ifs
--- a/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-size.ifs
+++ b/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-size.ifs
@@ -1,8 +1,8 @@
 # NOTE: Used by weak-mismatch.ifs
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  foobar: { Type: Object, Size: 2 }
+  - { Name: foobar, Type: Object, Size: 2 }
 ...
diff --git a/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-type.ifs b/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-type.ifs
--- a/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-type.ifs
+++ b/llvm/test/tools/llvm-ifs/Inputs/strong-mismatch-type.ifs
@@ -1,8 +1,8 @@
 # NOTE: Used by weak-mismatch.ifs
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  foobar: { Type: Func }
+  - { Name: foobar, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-header-format.ifs b/llvm/test/tools/llvm-ifs/conflict-header-format.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-header-format.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-header-format.ifs
@@ -5,10 +5,10 @@
 # CHECK-IFS-NEXT: Filenames:
 # CHECK-IFS-NEXT: ObjectFileFormat Values: TBD ELF
 
---- !experimental-ifs-v1
-IfsVersion:      1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple:          x86_64-apple-unknown
 ObjectFileFormat: TBD
 Symbols:
-  a:               { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-header-triple.ifs b/llvm/test/tools/llvm-ifs/conflict-header-triple.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-header-triple.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-header-triple.ifs
@@ -5,10 +5,10 @@
 # CHECK-IFS-NEXT: Filenames:
 # CHECK-IFS-NEXT: Triple Values: mips-unknown-linux x86_64-unknown-linux-gnu
 
---- !experimental-ifs-v1
-IfsVersion:      1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple:          mips-unknown-linux
 ObjectFileFormat: ELF
 Symbols:
-  a:               { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-header-version.ifs b/llvm/test/tools/llvm-ifs/conflict-header-version.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-header-version.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-header-version.ifs
@@ -5,12 +5,12 @@
 # RUN: FileCheck %s --check-prefixes=CHECK-IFS2
 
 # CHECK-IFS: error: Interface Stub: IfsVersion Mismatch.
-# CHECK-IFS2: error: Interface Stub: Bad IfsVersion: 0.0, llvm-ifs supported version: 1.2.
+# CHECK-IFS2: error: Interface Stub: Bad IfsVersion: 0.0, llvm-ifs supported version: 2.0.
 
---- !experimental-ifs-v1
+--- !experimental-ifs-v2
 IfsVersion:      0.0
 Triple:          x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a:               { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-size.ifs b/llvm/test/tools/llvm-ifs/conflict-size.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-size.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-size.ifs
@@ -7,10 +7,10 @@
 # CHECK-IFS-NEXT: Filename:
 # CHECK-IFS-NEXT: Size Values: 1 4
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  b: { Type: Object, Size: 1 }
+  - { Name: b, Type: Object, Size: 1 }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-type.ifs b/llvm/test/tools/llvm-ifs/conflict-type.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-type.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-type.ifs
@@ -7,10 +7,10 @@
 # CHECK-IFS-NEXT: Filename:
 # CHECK-IFS-NEXT: Type Values: Object Func
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a: { Type: Object, Size: 1 }
+  - { Name: a, Type: Object, Size: 1 }
 ...
diff --git a/llvm/test/tools/llvm-ifs/conflict-weak.ifs b/llvm/test/tools/llvm-ifs/conflict-weak.ifs
--- a/llvm/test/tools/llvm-ifs/conflict-weak.ifs
+++ b/llvm/test/tools/llvm-ifs/conflict-weak.ifs
@@ -2,12 +2,12 @@
 # RUN: FileCheck %s --check-prefixes=CHECK-IFS
 
 # CHECK-IFS: Symbols:
-# CHECK-IFS-NEXT: a: { Type: Func, Weak: true }
+# CHECK-IFS-NEXT: - { Name: a, Type: Func, Weak: true }
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a: { Type: Func, Weak: true }
+  - { Name: a, Type: Func, Weak: true }
 ...
diff --git a/llvm/test/tools/llvm-ifs/default-empty.ifs b/llvm/test/tools/llvm-ifs/default-empty.ifs
--- a/llvm/test/tools/llvm-ifs/default-empty.ifs
+++ b/llvm/test/tools/llvm-ifs/default-empty.ifs
@@ -1,25 +1,25 @@
 # RUN: llvm-ifs -action write-ifs -o - %s | FileCheck --check-prefixes=CHECK-DEFAULT %s
 # RUN: llvm-ifs -action write-ifs -o - %s %S/weak.ifs | FileCheck --check-prefixes=CHECK-MERGE %s
 
-# CHECK-DEFAULT: --- !experimental-ifs-v1
-# CHECK-DEFAULT-NEXT: IfsVersion:      1.2
+# CHECK-DEFAULT: --- !experimental-ifs-v2
+# CHECK-DEFAULT-NEXT: IfsVersion: 2.0
 # CHECK-DEFAULT-NEXT: Triple:          ''
 # CHECK-DEFAULT-NEXT: ObjectFileFormat: ELF
-# CHECK-DEFAULT-NEXT: Symbols:         {}
+# CHECK-DEFAULT-NEXT: Symbols:         []
 # CHECK-DEFAULT-NEXT: ...
 
-# CHECK-MERGE: --- !experimental-ifs-v1
-# CHECK-MERGE-NEXT: IfsVersion: 1.0
+# CHECK-MERGE: --- !experimental-ifs-v2
+# CHECK-MERGE-NEXT: IfsVersion: 2.0
 # CHECK-MERGE-NEXT: Triple: x86_64-unknown-linux-gnu
 # CHECK-MERGE-NEXT: ObjectFileFormat: ELF
 # CHECK-MERGE-NEXT: Symbols:
-# CHECK-MERGE-DAG:   _Z8weakFuncv: { Type: Func, Weak: true }
-# CHECK-MERGE-DAG:   _Z10strongFuncv: { Type: Func }
+# CHECK-MERGE-DAG:  - { Name: _Z8weakFuncv, Type: Func, Weak: true }
+# CHECK-MERGE-DAG:  - { Name: _Z10strongFuncv, Type: Func }
 # CHECK-MERGE: ...
 
---- !experimental-ifs-v1
-IfsVersion:      1.2
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple:          ''
 ObjectFileFormat: ELF
-Symbols:         {}
+Symbols:         []
 ...
diff --git a/llvm/test/tools/llvm-ifs/empty1.ifs b/llvm/test/tools/llvm-ifs/empty1.ifs
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-ifs/empty1.ifs
@@ -0,0 +1,15 @@
+# RUN: llvm-ifs -action write-ifs -o - %s | FileCheck %s
+
+# CHECK: --- !experimental-ifs-v2
+# CHECK-NEXT: IfsVersion: 2.0
+# CHECK-NEXT: Triple: x86_64-unknown-linux-gnu
+# CHECK-NEXT: ObjectFileFormat: ELF
+# CHECK-NEXT: Symbols: []
+# CHECK: ...
+
+--- !experimental-ifs-v2
+IfsVersion:      2.0
+Triple:          x86_64-unknown-linux-gnu
+ObjectFileFormat: ELF
+Symbols:         []
+...
diff --git a/llvm/test/tools/llvm-ifs/empty2.ifs b/llvm/test/tools/llvm-ifs/empty2.ifs
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-ifs/empty2.ifs
@@ -0,0 +1,15 @@
+# RUN: llvm-ifs -action write-ifs -o - %s | FileCheck %s
+
+# CHECK: --- !experimental-ifs-v2
+# CHECK-NEXT: IfsVersion: 2.0
+# CHECK-NEXT: Triple: x86_64-unknown-linux-gnu
+# CHECK-NEXT: ObjectFileFormat: ELF
+# CHECK-NEXT: Symbols: []
+# CHECK: ...
+
+--- !experimental-ifs-v2
+IfsVersion:      2.0
+Triple:          x86_64-unknown-linux-gnu
+ObjectFileFormat: ELF
+Symbols:
+...
diff --git a/llvm/test/tools/llvm-ifs/func.ifs b/llvm/test/tools/llvm-ifs/func.ifs
--- a/llvm/test/tools/llvm-ifs/func.ifs
+++ b/llvm/test/tools/llvm-ifs/func.ifs
@@ -10,13 +10,13 @@
 # RUN: llvm-ifs -action write-ifs -o - %s %s | \
 # RUN: FileCheck %s --check-prefixes=CHECK-MERGE-IFS
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion:      1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple:          x86_64-unknown-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-DAG:   a:               { Type: Func }
-# CHECK-IFS-DAG:   b:               { Type: Object, Size: 4 }
+# CHECK-IFS-DAG:   - { Name: a, Type: Func }
+# CHECK-IFS-DAG:   - { Name: b, Type: Object, Size: 4 }
 # CHECK-IFS: ...
 
 # CHECK-ELF: ELF Header:
@@ -39,18 +39,18 @@
 # CHECK-DARWIN-TBD3-NEXT: ...
 
 # Here we are testing to see if two identical symbols will merge.
-# CHECK-MERGE-IFS: --- !experimental-ifs-v1
-# CHECK-MERGE-IFS-NEXT: IfsVersion:      1.0
+# CHECK-MERGE-IFS: --- !experimental-ifs-v2
+# CHECK-MERGE-IFS-NEXT: IfsVersion: 2.0
 # CHECK-MERGE-IFS-NEXT: Triple:          x86_64-unknown-linux-gnu
 # CHECK-MERGE-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-MERGE-IFS-NEXT: Symbols:
-# CHECK-MERGE-IFS-NEXT:   a:               { Type: Func }
+# CHECK-MERGE-IFS-NEXT:   - { Name: a, Type: Func }
 # CHECK-MERGE-IFS-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a: { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/ios-tbd.ifs b/llvm/test/tools/llvm-ifs/ios-tbd.ifs
--- a/llvm/test/tools/llvm-ifs/ios-tbd.ifs
+++ b/llvm/test/tools/llvm-ifs/ios-tbd.ifs
@@ -13,10 +13,10 @@
 # CHECK-NEXT:     symbols:         [ __Z3fooi ]
 # CHECK-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: arm64-apple-ios
 ObjectFileFormat: TBD
 Symbols:
-  __Z3fooi: { Type: Func }
+  - { Name: __Z3fooi, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/macos-tbd.ifs b/llvm/test/tools/llvm-ifs/macos-tbd.ifs
--- a/llvm/test/tools/llvm-ifs/macos-tbd.ifs
+++ b/llvm/test/tools/llvm-ifs/macos-tbd.ifs
@@ -13,10 +13,10 @@
 # CHECK-NEXT:     symbols:         [ __Z3fooi ]
 # CHECK-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: arm64-apple-macosx
 ObjectFileFormat: TBD
 Symbols:
-  __Z3fooi: { Type: Func }
+  - { Name: __Z3fooi, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/object-function-size-weak-combo.ifs b/llvm/test/tools/llvm-ifs/object-function-size-weak-combo.ifs
--- a/llvm/test/tools/llvm-ifs/object-function-size-weak-combo.ifs
+++ b/llvm/test/tools/llvm-ifs/object-function-size-weak-combo.ifs
@@ -4,17 +4,17 @@
 # RUN: llvm-ifs -action write-bin -o - %s %S/func.ifs %S/object.ifs %S/weak.ifs | \
 # RUN: llvm-readelf --all | FileCheck %s --check-prefixes=CHECK-ELF
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion:      1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple:          x86_64-unknown-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-DAG:   e:               { Type: Object, Size: 8 }
-# CHECK-IFS-DAG:   a:               { Type: Func }
-# CHECK-IFS-DAG:   f:               { Type: Object, Size: 2 }
-# CHECK-IFS-DAG:   _Z10strongFuncv: { Type: Func }
-# CHECK-IFS-DAG:   _Z8weakFuncv:    { Type: Func, Weak: true }
-# CHECK-IFS-DAG:   b:               { Type: Object, Size: 4 }
+# CHECK-IFS-DAG:   - { Name: e,              Type: Object, Size: 8 }
+# CHECK-IFS-DAG:   - { Name: a,              Type: Func }
+# CHECK-IFS-DAG:   - { Name: f,              Type: Object, Size: 2 }
+# CHECK-IFS-DAG:   - { Name: _Z10strongFuncv, Type: Func }
+# CHECK-IFS-DAG:   - { Name: _Z8weakFuncv,   Type: Func, Weak: true }
+# CHECK-IFS-DAG:   - { Name: b,              Type: Object, Size: 4 }
 # CHECK-IFS: ...
 
 # CHECK-ELF: FUNC    GLOBAL DEFAULT  1 _Z10strongFuncv
@@ -24,11 +24,11 @@
 # CHECK-ELF: OBJECT  GLOBAL DEFAULT  1 e
 # CHECK-ELF: OBJECT  GLOBAL DEFAULT  1 f
 
---- !experimental-ifs-v1
-IfsVersion:      1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple:          x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  e:               { Type: Object, Size: 8 }
-  f:               { Type: Object, Size: 2 }
+  - { Name: e, Type: Object, Size: 8 }
+  - { Name: f, Type: Object, Size: 2 }
 ...
diff --git a/llvm/test/tools/llvm-ifs/object.ifs b/llvm/test/tools/llvm-ifs/object.ifs
--- a/llvm/test/tools/llvm-ifs/object.ifs
+++ b/llvm/test/tools/llvm-ifs/object.ifs
@@ -4,12 +4,12 @@
 # RUN: llvm-ifs -action write-bin -o - %s | \
 # RUN: llvm-readelf --all | FileCheck %s --check-prefixes=CHECK-ELF
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion:      1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple:          x86_64-unknown-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-NEXT:   b:               { Type: Object, Size: 4 }
+# CHECK-IFS-NEXT:   - { Name: b, Type: Object, Size: 4 }
 # CHECK-IFS-NEXT: ...
 
 # CHECK-ELF: ELF Header:
@@ -19,10 +19,10 @@
 # CHECK-ELF-NOT:   FUNC    GLOBAL DEFAULT  1 a
 # CHECK-ELF:   OBJECT  GLOBAL DEFAULT  1 b
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  b: { Type: Object, Size: 4 }
+  - { Name: b, Type: Object, Size: 4 }
 ...
diff --git a/llvm/test/tools/llvm-ifs/strong.ifs b/llvm/test/tools/llvm-ifs/strong.ifs
--- a/llvm/test/tools/llvm-ifs/strong.ifs
+++ b/llvm/test/tools/llvm-ifs/strong.ifs
@@ -1,17 +1,17 @@
 # RUN: llvm-ifs -action write-ifs -o - %s %S/strong.ifs | FileCheck %s --check-prefixes=CHECK-IFS
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion: 1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple: x86_64-unknown-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-DAG:   _Z8weakFuncv: { Type: Func }
+# CHECK-IFS-DAG:   - { Name: _Z8weakFuncv, Type: Func }
 # CHECK-IFS: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  _Z8weakFuncv: { Type: Func }
+  - { Name: _Z8weakFuncv, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/tvos-tbd.ifs b/llvm/test/tools/llvm-ifs/tvos-tbd.ifs
--- a/llvm/test/tools/llvm-ifs/tvos-tbd.ifs
+++ b/llvm/test/tools/llvm-ifs/tvos-tbd.ifs
@@ -13,10 +13,10 @@
 # CHECK-NEXT:     symbols:         [ __Z3fooi ]
 # CHECK-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: arm64-apple-tvos
 ObjectFileFormat: TBD
 Symbols:
-  __Z3fooi: { Type: Func }
+  - { Name: __Z3fooi, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/version-ok.ifs b/llvm/test/tools/llvm-ifs/version-ok.ifs
--- a/llvm/test/tools/llvm-ifs/version-ok.ifs
+++ b/llvm/test/tools/llvm-ifs/version-ok.ifs
@@ -1,9 +1,9 @@
 # RUN: llvm-ifs -action write-ifs -o - %s %S/object.ifs
 
---- !experimental-ifs-v1
-IfsVersion:      1.1
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple:          x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  a:               { Type: Func }
+  - { Name: a, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/watchos-tbd.ifs b/llvm/test/tools/llvm-ifs/watchos-tbd.ifs
--- a/llvm/test/tools/llvm-ifs/watchos-tbd.ifs
+++ b/llvm/test/tools/llvm-ifs/watchos-tbd.ifs
@@ -13,10 +13,10 @@
 # CHECK-NEXT:     symbols:         [ __Z3fooi ]
 # CHECK-NEXT: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: arm64-apple-watchos
 ObjectFileFormat: TBD
 Symbols:
-  __Z3fooi: { Type: Func }
+  - { Name: __Z3fooi, Type: Func }
 ...
diff --git a/llvm/test/tools/llvm-ifs/weak-mismatch.ifs b/llvm/test/tools/llvm-ifs/weak-mismatch.ifs
--- a/llvm/test/tools/llvm-ifs/weak-mismatch.ifs
+++ b/llvm/test/tools/llvm-ifs/weak-mismatch.ifs
@@ -10,10 +10,10 @@
 # CHECK-TYPE-NEXT: Filename:
 # CHECK-TYPE-NEXT: Type Values: Object Func
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  foobar: { Type: Object, Size: 1, Weak: true }
+  - { Name: foobar, Type: Object, Size: 1, Weak: true }
 ...
diff --git a/llvm/test/tools/llvm-ifs/weak.ifs b/llvm/test/tools/llvm-ifs/weak.ifs
--- a/llvm/test/tools/llvm-ifs/weak.ifs
+++ b/llvm/test/tools/llvm-ifs/weak.ifs
@@ -1,19 +1,19 @@
 # RUN: llvm-ifs -action write-ifs -o - %s | FileCheck %s --check-prefixes=CHECK-IFS
 
-# CHECK-IFS: --- !experimental-ifs-v1
-# CHECK-IFS-NEXT: IfsVersion: 1.0
+# CHECK-IFS: --- !experimental-ifs-v2
+# CHECK-IFS-NEXT: IfsVersion: 2.0
 # CHECK-IFS-NEXT: Triple: x86_64-unknown-linux-gnu
 # CHECK-IFS-NEXT: ObjectFileFormat: ELF
 # CHECK-IFS-NEXT: Symbols:
-# CHECK-IFS-DAG:   _Z8weakFuncv: { Type: Func, Weak: true }
-# CHECK-IFS-DAG:   _Z10strongFuncv: { Type: Func }
+# CHECK-IFS-DAG:   - { Name: _Z8weakFuncv, Type: Func, Weak: true }
+# CHECK-IFS-DAG:   - { Name: _Z10strongFuncv, Type: Func }
 # CHECK-IFS: ...
 
---- !experimental-ifs-v1
-IfsVersion: 1.0
+--- !experimental-ifs-v2
+IfsVersion: 2.0
 Triple: x86_64-unknown-linux-gnu
 ObjectFileFormat: ELF
 Symbols:
-  _Z8weakFuncv: { Type: Func, Weak: true }
-  _Z10strongFuncv: { Type: Func }
+  - { Name: _Z8weakFuncv, Type: Func, Weak: true }
+  - { Name: _Z10strongFuncv, Type: Func }
 ...
diff --git a/llvm/tools/llvm-ifs/llvm-ifs.cpp b/llvm/tools/llvm-ifs/llvm-ifs.cpp
--- a/llvm/tools/llvm-ifs/llvm-ifs.cpp
+++ b/llvm/tools/llvm-ifs/llvm-ifs.cpp
@@ -26,6 +26,7 @@
 #include "llvm/TextAPI/MachO/TextAPIWriter.h"
 #include <set>
 #include <string>
+#include <vector>
 
 using namespace llvm;
 using namespace llvm::yaml;
@@ -34,8 +35,8 @@
 #define DEBUG_TYPE "llvm-ifs"
 
 namespace {
-const VersionTuple IFSVersionCurrent(1, 2);
-}
+const VersionTuple IFSVersionCurrent(2, 0);
+} // end anonymous namespace
 
 static cl::opt<std::string> Action("action", cl::desc("<llvm-ifs action>"),
                                    cl::value_desc("write-ifs | write-bin"),
@@ -76,6 +77,7 @@
 }
 
 struct IFSSymbol {
+  IFSSymbol() = default;
   IFSSymbol(std::string SymbolName) : Name(SymbolName) {}
   std::string Name;
   uint64_t Size;
@@ -85,6 +87,8 @@
   bool operator<(const IFSSymbol &RHS) const { return Name < RHS.Name; }
 };
 
+LLVM_YAML_IS_SEQUENCE_VECTOR(IFSSymbol)
+
 namespace llvm {
 namespace yaml {
 /// YAML traits for IFSSymbolType.
@@ -124,6 +128,7 @@
 /// YAML traits for IFSSymbol.
 template <> struct MappingTraits<IFSSymbol> {
   static void mapping(IO &IO, IFSSymbol &Symbol) {
+    IO.mapRequired("Name", Symbol.Name);
     IO.mapRequired("Type", Symbol.Type);
     // The need for symbol size depends on the symbol type.
     if (Symbol.Type == IFSSymbolType::NoType)
@@ -140,20 +145,6 @@
   static const bool flow = true;
 };
 
-/// YAML traits for set of IFSSymbols.
-template <> struct CustomMappingTraits<std::set<IFSSymbol>> {
-  static void inputOne(IO &IO, StringRef Key, std::set<IFSSymbol> &Set) {
-    std::string Name = Key.str();
-    IFSSymbol Sym(Name);
-    IO.mapRequired(Name.c_str(), Sym);
-    Set.insert(Sym);
-  }
-
-  static void output(IO &IO, std::set<IFSSymbol> &Set) {
-    for (auto &Sym : Set)
-      IO.mapRequired(Sym.Name.c_str(), const_cast<IFSSymbol &>(Sym));
-  }
-};
 } // namespace yaml
 } // namespace llvm
 
@@ -167,7 +158,7 @@
   std::string ObjectFileFormat;
   Optional<std::string> SOName;
   std::vector<std::string> NeededLibs;
-  std::set<IFSSymbol> Symbols;
+  std::vector<IFSSymbol> Symbols;
 
   IFSStub() = default;
   IFSStub(const IFSStub &Stub)
@@ -186,14 +177,18 @@
 /// YAML traits for IFSStub objects.
 template <> struct MappingTraits<IFSStub> {
   static void mapping(IO &IO, IFSStub &Stub) {
-    if (!IO.mapTag("!experimental-ifs-v1", true))
+    if (!IO.mapTag("!experimental-ifs-v2", true))
       IO.setError("Not a .ifs YAML file.");
+
+    auto oldContext = IO.getContext();
+    IO.setContext(&Stub);
     IO.mapRequired("IfsVersion", Stub.IfsVersion);
     IO.mapOptional("Triple", Stub.Triple);
     IO.mapOptional("ObjectFileFormat", Stub.ObjectFileFormat);
     IO.mapOptional("SOName", Stub.SOName);
     IO.mapOptional("NeededLibs", Stub.NeededLibs);
     IO.mapRequired("Symbols", Stub.Symbols);
+    IO.setContext(&oldContext);
   }
 };
 } // namespace yaml
@@ -218,7 +213,7 @@
   return std::move(Stub);
 }
 
-int writeTbdStub(const llvm::Triple &T, const std::set<IFSSymbol> &Symbols,
+int writeTbdStub(const llvm::Triple &T, const std::vector<IFSSymbol> &Symbols,
                  const StringRef Format, raw_ostream &Out) {
 
   auto PlatformKindOrError =
@@ -280,7 +275,7 @@
   return 0;
 }
 
-int writeElfStub(const llvm::Triple &T, const std::set<IFSSymbol> &Symbols,
+int writeElfStub(const llvm::Triple &T, const std::vector<IFSSymbol> &Symbols,
                  const StringRef Format, raw_ostream &Out) {
   SmallString<0> Storage;
   Storage.clear();
@@ -387,8 +382,8 @@
 
 // TODO: Drop ObjectFileFormat, it can be subsumed from the triple.
 // New Interface Stubs Yaml Format:
-// --- !experimental-ifs-v1
-// IfsVersion:      1.0
+// --- !experimental-ifs-v2
+// IfsVersion: 2.0
 // Triple:          <llvm triple>
 // ObjectFileFormat: <ELF | others not yet supported>
 // Symbols:
@@ -517,7 +512,7 @@
     }
 
   for (auto &Entry : SymbolMap)
-    Stub.Symbols.insert(Entry.second);
+    Stub.Symbols.push_back(Entry.second);
 
   std::error_code SysErr;