am 9c1912c4: Merge "Avoid changing the C++ ABI with ssize_t."

* commit '9c1912c4bf5eb0edc07bfd333226c4e0b7a629eb':
  Avoid changing the C++ ABI with ssize_t.

libc/include/sys/types.h

@@ -85,8 +85,17 @@ typedef  .... pthread_t;
 
 #ifndef _SSIZE_T_DEFINED_
 #define _SSIZE_T_DEFINED_
+/* Traditionally, bionic's ssize_t was "long int". This causes GCC to emit warnings when you
+ * pass a ssize_t to a printf-style function. The correct type is __kernel_ssize_t, which is
+ * "int", which isn't an ABI change for C code (because they're the same size) but is an ABI
+ * change for C++ because "int" and "long int" mangle to "i" and "l" respectively. So until
+ * we can fix the ABI, this is the best we can do. http://b/8253769. */
+#if defined(__cplusplus)
+typedef long int  ssize_t;
+#else
 typedef __kernel_ssize_t ssize_t;
 #endif
+#endif
 
 typedef __kernel_suseconds_t  suseconds_t;
 typedef __kernel_time_t       time_t;

tests/stdio_test.cpp

@@ -171,10 +171,17 @@ TEST(stdio, getline_invalid) {
 }
 
 TEST(stdio, printf_ssize_t) {
-  // We used to have a ssize_t definition that confused GCC into saying:
+#if __BIONIC__
+  // http://b/8253769
+  ASSERT_EQ(sizeof(__kernel_ssize_t), sizeof(long int));
+  ASSERT_EQ(sizeof(ssize_t), sizeof(long int));
+#else
+  // TODO: add a .c file so we can test this for bionic --- our C ssize_t is fine.
+  // For our 32-bit C++ ABI, we have a ssize_t definition that confuses GCC into saying:
   // error: format '%zd' expects argument of type 'signed size_t',
   //     but argument 4 has type 'ssize_t {aka long int}' [-Werror=format]
   ssize_t v = 1;
   char buf[32];
   snprintf(buf, sizeof(buf), "%zd", v);
+#endif
 }