tcmalloc: move includes for mallinfo from tcmalloc.cc to tcmalloc.h

base/allocator/allocator.gyp

Index: base/allocator/allocator.gyp
diff --git a/base/allocator/allocator.gyp b/base/allocator/allocator.gyp
index e2c8ac0faeb383fd96b138b1f99b23c830ab21bb..d4043b50c03bda70bc1ba70c2ee779c492377a6a 100644
--- a/base/allocator/allocator.gyp
+++ b/base/allocator/allocator.gyp
@@ -394,6 +394,13 @@
               '-Wl,-u_ZN15HeapLeakChecker12IgnoreObjectEPKv,-u_ZN15HeapLeakChecker14UnIgnoreObjectEPKv',
           ]},
         }],
+        [ 'clang==1', {
+          'cflags': [
+            # tcmalloc.h declares "struct mallinfo tc_mallinfo(void)"
+            # with c-style linkage.

[Nico, 2012/07/24 13:38:16]

Do you know why the warning fires on this?

[hans, 2012/07/24 13:49:13]

Yes, tc_mallinfo is declared inside an 'extern "C"' block, which means that the
function name will not be mangled. However, 'struct mallinfo' is a C++ type, so
calling it from C code wouldn't work. This is what the warning is about.

However, as long as the function is defined in C++, and only called from c++
code, everything is fine (see e.g.
http://msdn.microsoft.com/en-us/library/1e02627y.aspx).

The reason for not wanting to mangle the name could be that the library wants to
have a nice name for the function to pass to libtool, or something similar.

This was also discussed when the warning was added to Clang, see e.g.
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20120206/052972.html

+            '-Wno-return-type-c-linkage',
+          ],
+        }],
         [ 'linux_use_debugallocation==1', {
           'sources!': [
             # debugallocation.cc #includes tcmalloc.cc,