diff --git a/tools/versioner/src/DeclarationDatabase.cpp b/tools/versioner/src/DeclarationDatabase.cpp
index 247e58b..aef4f55 100644
--- a/tools/versioner/src/DeclarationDatabase.cpp
+++ b/tools/versioner/src/DeclarationDatabase.cpp
@@ -54,17 +54,19 @@
       }
     }
 
-    if (mangler->shouldMangleDeclName(decl)) {
-      std::string mangled;
-      llvm::raw_string_ostream ss(mangled);
-      mangler->mangleName(decl, ss);
-      return mangled;
-    }
-
+    // The decl might not have a name (e.g. bitfields).
     if (auto identifier = decl->getIdentifier()) {
+      if (mangler->shouldMangleDeclName(decl)) {
+        std::string mangled;
+        llvm::raw_string_ostream ss(mangled);
+        mangler->mangleName(decl, ss);
+        return mangled;
+      }
+
       return identifier->getName();
     }
-    return "<error>";
+
+    return "<unnamed>";
   }
 
   bool VisitDecl(Decl* decl) {
diff --git a/tools/versioner/tests/arch_specific/headers/foo.h b/tools/versioner/tests/arch_specific/headers/foo.h
index 34035b4..4830a68 100644
--- a/tools/versioner/tests/arch_specific/headers/foo.h
+++ b/tools/versioner/tests/arch_specific/headers/foo.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int foo();
 
 #if defined(__i386__)
 int bar();
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/compilation_error/headers/foo.h b/tools/versioner/tests/compilation_error/headers/foo.h
index c8c1473..51c087a 100644
--- a/tools/versioner/tests/compilation_error/headers/foo.h
+++ b/tools/versioner/tests/compilation_error/headers/foo.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #error foo
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/dependencies/dependencies/arm/archdep/archdep.h b/tools/versioner/tests/dependencies/dependencies/arm/archdep/archdep.h
index 2005972..b2d357a 100644
--- a/tools/versioner/tests/dependencies/dependencies/arm/archdep/archdep.h
+++ b/tools/versioner/tests/dependencies/dependencies/arm/archdep/archdep.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 typedef int arm_t;
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/dependencies/dependencies/common/foo/foodep.h b/tools/versioner/tests/dependencies/dependencies/common/foo/foodep.h
index 9feeb6c..baa5857 100644
--- a/tools/versioner/tests/dependencies/dependencies/common/foo/foodep.h
+++ b/tools/versioner/tests/dependencies/dependencies/common/foo/foodep.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 typedef int foo_t;
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/dependencies/dependencies/x86/archdep/archdep.h b/tools/versioner/tests/dependencies/dependencies/x86/archdep/archdep.h
index 5cc7de2..b73f7cc 100644
--- a/tools/versioner/tests/dependencies/dependencies/x86/archdep/archdep.h
+++ b/tools/versioner/tests/dependencies/dependencies/x86/archdep/archdep.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 typedef int x86_t;
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/dependencies/headers/foo.h b/tools/versioner/tests/dependencies/headers/foo.h
index 4491f1c..875de1b 100644
--- a/tools/versioner/tests/dependencies/headers/foo.h
+++ b/tools/versioner/tests/dependencies/headers/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #include <archdep.h>
 #include <foodep.h>
 
@@ -6,3 +10,7 @@
 #elif defined(__arm__)
 arm_t foo(foo_t);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/future/headers/foo.h b/tools/versioner/tests/future/headers/foo.h
index 54e8f0c..51a3a1c 100644
--- a/tools/versioner/tests/future/headers/foo.h
+++ b/tools/versioner/tests/future/headers/foo.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int foo() __INTRODUCED_IN_FUTURE;
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/future_arch/headers/foo.h b/tools/versioner/tests/future_arch/headers/foo.h
index 9dd976e..a3258e7 100644
--- a/tools/versioner/tests/future_arch/headers/foo.h
+++ b/tools/versioner/tests/future_arch/headers/foo.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if defined(__arm__)
 int foo() __INTRODUCED_IN(9);
 #else
 int foo() __INTRODUCED_IN_FUTURE;
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/inline/headers/foo.h b/tools/versioner/tests/inline/headers/foo.h
index a61b386..a337f9c 100644
--- a/tools/versioner/tests/inline/headers/foo.h
+++ b/tools/versioner/tests/inline/headers/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ < 12
 static int foo() {
   return 0;
@@ -5,3 +9,7 @@
 #else
 int foo() __INTRODUCED_IN(12);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/missing_api/expected_fail b/tools/versioner/tests/missing_api/expected_fail
index 18e7845..9f097f7 100644
--- a/tools/versioner/tests/missing_api/expected_fail
+++ b/tools/versioner/tests/missing_api/expected_fail
@@ -1,4 +1,4 @@
   foo: introduced = 9
-    extern declaration @ headers/foo.h:1:1
+    extern declaration @ headers/foo.h:5:1
       introduced = 9
 versioner: version check failed
diff --git a/tools/versioner/tests/missing_api/headers/foo.h b/tools/versioner/tests/missing_api/headers/foo.h
index 3ff3ff7..c201dbb 100644
--- a/tools/versioner/tests/missing_api/headers/foo.h
+++ b/tools/versioner/tests/missing_api/headers/foo.h
@@ -1 +1,9 @@
-int foo() __INTRODUCED_IN(9);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __INTRODUCED_IN(9);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/missing_arch/expected_fail b/tools/versioner/tests/missing_arch/expected_fail
index 82c2b28..7b33e19 100644
--- a/tools/versioner/tests/missing_arch/expected_fail
+++ b/tools/versioner/tests/missing_arch/expected_fail
@@ -1,4 +1,4 @@
   foo: no availability
-    extern declaration @ headers/foo.h:1:1
+    extern declaration @ headers/foo.h:5:1
       no availability
 versioner: version check failed
diff --git a/tools/versioner/tests/missing_arch/headers/foo.h b/tools/versioner/tests/missing_arch/headers/foo.h
index 176e7a3..5ba4794 100644
--- a/tools/versioner/tests/missing_arch/headers/foo.h
+++ b/tools/versioner/tests/missing_arch/headers/foo.h
@@ -1 +1,9 @@
-int foo();
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo();
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_decl/headers/bar.h b/tools/versioner/tests/multiple_decl/headers/bar.h
index 1d3a28c..b16617b 100644
--- a/tools/versioner/tests/multiple_decl/headers/bar.h
+++ b/tools/versioner/tests/multiple_decl/headers/bar.h
@@ -1 +1,9 @@
-int foo() __REMOVED_IN(12);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __REMOVED_IN(12);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_decl/headers/foo.h b/tools/versioner/tests/multiple_decl/headers/foo.h
index 1d3a28c..b16617b 100644
--- a/tools/versioner/tests/multiple_decl/headers/foo.h
+++ b/tools/versioner/tests/multiple_decl/headers/foo.h
@@ -1 +1,9 @@
-int foo() __REMOVED_IN(12);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __REMOVED_IN(12);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_decl_mismatch/expected_fail b/tools/versioner/tests/multiple_decl_mismatch/expected_fail
index 8e8c846..1d1f266 100644
--- a/tools/versioner/tests/multiple_decl_mismatch/expected_fail
+++ b/tools/versioner/tests/multiple_decl_mismatch/expected_fail
@@ -1,8 +1,8 @@
 versioner: inconsistent availability for symbol 'foo'
 versioner: failed to calculate symbol availability
   foo: invalid
-    extern declaration @ headers/bar.h:1:1
+    extern declaration @ headers/bar.h:5:1
       obsoleted = 12
-    extern declaration @ headers/foo.h:1:1
+    extern declaration @ headers/foo.h:5:1
       obsoleted = 9
 versioner: sanity check failed
diff --git a/tools/versioner/tests/multiple_decl_mismatch/headers/bar.h b/tools/versioner/tests/multiple_decl_mismatch/headers/bar.h
index 1d3a28c..b16617b 100644
--- a/tools/versioner/tests/multiple_decl_mismatch/headers/bar.h
+++ b/tools/versioner/tests/multiple_decl_mismatch/headers/bar.h
@@ -1 +1,9 @@
-int foo() __REMOVED_IN(12);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __REMOVED_IN(12);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_decl_mismatch/headers/foo.h b/tools/versioner/tests/multiple_decl_mismatch/headers/foo.h
index 49a73ec..8e8f98c 100644
--- a/tools/versioner/tests/multiple_decl_mismatch/headers/foo.h
+++ b/tools/versioner/tests/multiple_decl_mismatch/headers/foo.h
@@ -1 +1,9 @@
-int foo() __REMOVED_IN(9);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __REMOVED_IN(9);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_definition/expected_fail b/tools/versioner/tests/multiple_definition/expected_fail
index 6c531bd..7070390 100644
--- a/tools/versioner/tests/multiple_definition/expected_fail
+++ b/tools/versioner/tests/multiple_definition/expected_fail
@@ -1,7 +1,7 @@
 versioner: conflicting inline definitions:
   declarations visible in: arm-9 [fob = 32], arm-9 [fob = 64], arm-12 [fob = 32], arm-12 [fob = 64]
-    static definition @ headers/foo.h:1:1
+    static definition @ headers/foo.h:5:1
       no availability
-    static definition @ headers/bar.h:1:1
+    static definition @ headers/bar.h:5:1
       no availability
 versioner: sanity check failed
diff --git a/tools/versioner/tests/multiple_definition/headers/bar.h b/tools/versioner/tests/multiple_definition/headers/bar.h
index a9d0197..29592c6 100644
--- a/tools/versioner/tests/multiple_definition/headers/bar.h
+++ b/tools/versioner/tests/multiple_definition/headers/bar.h
@@ -1,3 +1,11 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 static int foo() {
   return 0;
 }
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_definition/headers/foo.h b/tools/versioner/tests/multiple_definition/headers/foo.h
index a9d0197..29592c6 100644
--- a/tools/versioner/tests/multiple_definition/headers/foo.h
+++ b/tools/versioner/tests/multiple_definition/headers/foo.h
@@ -1,3 +1,11 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 static int foo() {
   return 0;
 }
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_definition_ok/headers/bar.h b/tools/versioner/tests/multiple_definition_ok/headers/bar.h
index c3c87bb..6eced51 100644
--- a/tools/versioner/tests/multiple_definition_ok/headers/bar.h
+++ b/tools/versioner/tests/multiple_definition_ok/headers/bar.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ == 12
 static int foo() {
   return 0;
 }
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/multiple_definition_ok/headers/foo.h b/tools/versioner/tests/multiple_definition_ok/headers/foo.h
index 9da9b2a..773d274 100644
--- a/tools/versioner/tests/multiple_definition_ok/headers/foo.h
+++ b/tools/versioner/tests/multiple_definition_ok/headers/foo.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ == 9
 static int foo() {
   return 0;
 }
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/obsoleted/headers/foo.h b/tools/versioner/tests/obsoleted/headers/foo.h
index 68f3d43..e9630e5 100644
--- a/tools/versioner/tests/obsoleted/headers/foo.h
+++ b/tools/versioner/tests/obsoleted/headers/foo.h
@@ -1 +1,9 @@
-int foo() __INTRODUCED_IN(9) __REMOVED_IN(11);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __INTRODUCED_IN(9) __REMOVED_IN(11);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor/expected/foo.h b/tools/versioner/tests/preprocessor/expected/foo.h
index 73947b2..cb719f0 100644
--- a/tools/versioner/tests/preprocessor/expected/foo.h
+++ b/tools/versioner/tests/preprocessor/expected/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int always_available();
 
 int also_always_available() __INTRODUCED_IN(9);
@@ -74,3 +78,7 @@
 int future() __INTRODUCED_IN_FUTURE;
 #endif /* __ANDROID_API__ >= __ANDROID_API_FUTURE__ */
 
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor/headers/foo.h b/tools/versioner/tests/preprocessor/headers/foo.h
index 81c8b4b..2429334 100644
--- a/tools/versioner/tests/preprocessor/headers/foo.h
+++ b/tools/versioner/tests/preprocessor/headers/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int always_available();
 
 int also_always_available() __INTRODUCED_IN(9);
@@ -42,3 +46,7 @@
 int group_lp32() __INTRODUCED_IN_ARM(12) __INTRODUCED_IN_X86(12) __INTRODUCED_IN_MIPS(12);
 
 int future() __INTRODUCED_IN_FUTURE;
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_file_offset_bits/expected/foo.h b/tools/versioner/tests/preprocessor_file_offset_bits/expected/foo.h
index 7d31ec3..dcfaaee 100644
--- a/tools/versioner/tests/preprocessor_file_offset_bits/expected/foo.h
+++ b/tools/versioner/tests/preprocessor_file_offset_bits/expected/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 typedef int off_t;
 typedef int ssize_t;
 typedef unsigned size_t;
@@ -32,3 +36,7 @@
 #else
 off_t lseek(int __fd, off_t __offset, int __whence);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_file_offset_bits/headers/foo.h b/tools/versioner/tests/preprocessor_file_offset_bits/headers/foo.h
index 868d1fc..5ffffa8 100644
--- a/tools/versioner/tests/preprocessor_file_offset_bits/headers/foo.h
+++ b/tools/versioner/tests/preprocessor_file_offset_bits/headers/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 typedef int off_t;
 typedef int ssize_t;
 typedef unsigned size_t;
@@ -28,3 +32,7 @@
 #else
 off_t lseek(int __fd, off_t __offset, int __whence);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_idempotence/expected/foo.h b/tools/versioner/tests/preprocessor_idempotence/expected/foo.h
index ed31e8b..bc442e5 100644
--- a/tools/versioner/tests/preprocessor_idempotence/expected/foo.h
+++ b/tools/versioner/tests/preprocessor_idempotence/expected/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ >= 10
 int foo() __INTRODUCED_IN(10);
 #endif
@@ -10,3 +14,7 @@
 int multiple_1() __INTRODUCED_IN(10);
 int multiple_2() __INTRODUCED_IN(10);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_idempotence/headers/foo.h b/tools/versioner/tests/preprocessor_idempotence/headers/foo.h
index ed31e8b..bc442e5 100644
--- a/tools/versioner/tests/preprocessor_idempotence/headers/foo.h
+++ b/tools/versioner/tests/preprocessor_idempotence/headers/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ >= 10
 int foo() __INTRODUCED_IN(10);
 #endif
@@ -10,3 +14,7 @@
 int multiple_1() __INTRODUCED_IN(10);
 int multiple_2() __INTRODUCED_IN(10);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_merging/expected/foo.h b/tools/versioner/tests/preprocessor_merging/expected/foo.h
index 45eb32d..ecd7f71 100644
--- a/tools/versioner/tests/preprocessor_merging/expected/foo.h
+++ b/tools/versioner/tests/preprocessor_merging/expected/foo.h
@@ -1,3 +1,7 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 
 #if __ANDROID_API__ >= 10
 int block_merging_1() __INTRODUCED_IN(10); // foo
@@ -7,3 +11,7 @@
 int block_merging_4() __INTRODUCED_IN(10);
 #endif /* __ANDROID_API__ >= 10 */
 
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_merging/headers/foo.h b/tools/versioner/tests/preprocessor_merging/headers/foo.h
index ac9564b..7aaa471 100644
--- a/tools/versioner/tests/preprocessor_merging/headers/foo.h
+++ b/tools/versioner/tests/preprocessor_merging/headers/foo.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int block_merging_1() __INTRODUCED_IN(10); // foo
 int block_merging_2() __INTRODUCED_IN(10); /* bar */
 int block_merging_3() __INTRODUCED_IN(10); /* baz
 //*/
 int block_merging_4() __INTRODUCED_IN(10);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_no_guard/expected/foo.h b/tools/versioner/tests/preprocessor_no_guard/expected/foo.h
index 2bf1dbf..3ef0c30 100644
--- a/tools/versioner/tests/preprocessor_no_guard/expected/foo.h
+++ b/tools/versioner/tests/preprocessor_no_guard/expected/foo.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int foo() __VERSIONER_NO_GUARD __INTRODUCED_IN(14);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/preprocessor_no_guard/headers/foo.h b/tools/versioner/tests/preprocessor_no_guard/headers/foo.h
index 2bf1dbf..3ef0c30 100644
--- a/tools/versioner/tests/preprocessor_no_guard/headers/foo.h
+++ b/tools/versioner/tests/preprocessor_no_guard/headers/foo.h
@@ -1 +1,9 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 int foo() __VERSIONER_NO_GUARD __INTRODUCED_IN(14);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/smoke/headers/foo.h b/tools/versioner/tests/smoke/headers/foo.h
index 3ff3ff7..c201dbb 100644
--- a/tools/versioner/tests/smoke/headers/foo.h
+++ b/tools/versioner/tests/smoke/headers/foo.h
@@ -1 +1,9 @@
-int foo() __INTRODUCED_IN(9);
\ No newline at end of file
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+int foo() __INTRODUCED_IN(9);
+
+#if defined(__cplusplus)
+}
+#endif
diff --git a/tools/versioner/tests/version_mismatch/expected_fail b/tools/versioner/tests/version_mismatch/expected_fail
index f83f71c..f2143a3 100644
--- a/tools/versioner/tests/version_mismatch/expected_fail
+++ b/tools/versioner/tests/version_mismatch/expected_fail
@@ -1,8 +1,8 @@
 versioner: inconsistent availability for symbol 'foo'
 versioner: failed to calculate symbol availability
   foo: invalid
-    extern declaration @ headers/foo.h:2:1
+    extern declaration @ headers/foo.h:6:1
       introduced = 9
-    extern declaration @ headers/foo.h:4:1
+    extern declaration @ headers/foo.h:8:1
       introduced = 10
 versioner: sanity check failed
diff --git a/tools/versioner/tests/version_mismatch/headers/foo.h b/tools/versioner/tests/version_mismatch/headers/foo.h
index 4604092..ea35f36 100644
--- a/tools/versioner/tests/version_mismatch/headers/foo.h
+++ b/tools/versioner/tests/version_mismatch/headers/foo.h
@@ -1,5 +1,13 @@
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #if __ANDROID_API__ <= 9
 int foo() __INTRODUCED_IN(9);
 #else
 int foo() __INTRODUCED_IN(10);
 #endif
+
+#if defined(__cplusplus)
+}
+#endif