cppgc: Use static_assert to force semi colon after macro

Bug: chromium:1056170
Change-Id: I1b6787ecea6ad58173a0bcc8e8d0862a5b19d299
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2199342
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67784}

include/cppgc/garbage-collected.h

@@ -8,7 +8,6 @@
 #include <type_traits>
 
 #include "cppgc/internal/api-constants.h"
-#include "cppgc/macros.h"
 #include "cppgc/platform.h"
 #include "cppgc/trace-trait.h"
 #include "cppgc/type-traits.h"
@@ -161,7 +160,7 @@ class GarbageCollectedMixin : public internal::GarbageCollectedBase {
   }                                                                          \
                                                                              \
  private:                                                                    \
-  friend class internal::__thisIsHereToForceASemicolonAfterThisMacro
+  static_assert(true, "Force semicolon.")
 
 /**
  * Merge two or more Mixins into one.
@@ -185,7 +184,7 @@ class GarbageCollectedMixin : public internal::GarbageCollectedBase {
   }                                                     \
                                                         \
  private:                                               \
-  friend class internal::__thisIsHereToForceASemicolonAfterThisMacro
+  static_assert(true, "Force semicolon.")
 
 }  // namespace cppgc
 

include/cppgc/macros.h

@@ -7,10 +7,6 @@
 
 namespace cppgc {
 
-namespace internal {
-class __thisIsHereToForceASemicolonAfterThisMacro {};
-}  // namespace internal
-
 // Use if the object is only stack allocated.
 #define CPPGC_STACK_ALLOCATED()               \
  public:                                      \
@@ -19,7 +15,7 @@ class __thisIsHereToForceASemicolonAfterThisMacro {};
  private:                                     \
   void* operator new(size_t) = delete;        \
   void* operator new(size_t, void*) = delete; \
-  friend class internal::__thisIsHereToForceASemicolonAfterThisMacro
+  static_assert(true, "Force semicolon.")
 
 }  // namespace cppgc
 

include/cppgc/prefinalizer.h

@@ -9,7 +9,6 @@
 #include "cppgc/internal/compiler-specific.h"
 #include "cppgc/internal/prefinalizer-handler.h"
 #include "cppgc/liveness-broker.h"
-#include "cppgc/macros.h"
 
 namespace cppgc {
 
@@ -47,7 +46,7 @@ class PrefinalizerRegistration final {
  private:                                                                   \
   CPPGC_NO_UNIQUE_ADDRESS internal::PrefinalizerRegistration<Class>         \
       prefinalizer_dummy_{this};                                            \
-  friend class internal::__thisIsHereToForceASemicolonAfterThisMacro
+  static_assert(true, "Force semicolon.")
 
 }  // namespace cppgc
 

src/heap/cppgc/heap.h

@@ -12,6 +12,7 @@
 #include "include/cppgc/internal/gc-info.h"
 #include "include/cppgc/internal/persistent-node.h"
 #include "include/cppgc/liveness-broker.h"
+#include "include/cppgc/macros.h"
 #include "src/base/page-allocator.h"
 #include "src/heap/cppgc/heap-object-header.h"
 #include "src/heap/cppgc/marker.h"