[libunwind] Fflush stderr after each log message

In most configs, stderr is line buffered by default, but in some cases on Windows (running in git bash, or running in Wine) stderr can end up fully buffered. See 2ec75a0 for a similar change for the output from lit itself. This has no effect on libunwind when the log messages aren't enabled via the environment variables. Differential Revision: https://reviews.llvm.org/D147632
intel · Apr 6, 2023 · a33d5a9 · a33d5a9
1 parent a017aef
commit a33d5a9
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/libunwind/src/config.h b/libunwind/src/config.h
@@ -162,10 +162,14 @@
 #define _LIBUNWIND_LOG0(msg)
 #define _LIBUNWIND_LOG(msg, ...)
 #else
-#define _LIBUNWIND_LOG0(msg)                                               \
-  fprintf(stderr, "libunwind: " msg "\n")
-#define _LIBUNWIND_LOG(msg, ...)                                               \
-  fprintf(stderr, "libunwind: " msg "\n", __VA_ARGS__)
+#define _LIBUNWIND_LOG0(msg) do {                                              \
+    fprintf(stderr, "libunwind: " msg "\n");                                   \
+    fflush(stderr);                                                            \
+  } while (0)
+#define _LIBUNWIND_LOG(msg, ...) do {                                          \
+    fprintf(stderr, "libunwind: " msg "\n", __VA_ARGS__);                      \
+    fflush(stderr);                                                            \
+  } while (0)
 #endif
 
 #if defined(NDEBUG)