From 2e5cb2ea82b6bd1ce25a2cd76f31c0b9a2d0e6f2 Mon Sep 17 00:00:00 2001
From: Christian Helmuth <christian.helmuth@genode-labs.com>
Date: Mon, 31 Mar 2014 16:47:12 +0200
Subject: [PATCH] Use do statement in PDBG and PWRN

The do statement ensures the macros to generate just one expression that
is compatible with any programming construct. The concrete bug was

  if (cond)
    PDBG(...);
  else
    ...

which was expanded to

  if (cond)
    if (DO_PDBG)
      Genode::printf(...);
  else
    ...

This is obviously wrong as the *else* branch is then connected to the
second *if*.
---
 base/include/base/printf.h | 40 ++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/base/include/base/printf.h b/base/include/base/printf.h
index c215d657e6..ef514d0f4b 100644
--- a/base/include/base/printf.h
+++ b/base/include/base/printf.h
@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (C) 2006-2013 Genode Labs GmbH
+ * Copyright (C) 2006-2014 Genode Labs GmbH
  *
  * This file is part of the Genode OS framework, which is distributed
  * under the terms of the GNU General Public License version 2.
@@ -50,19 +50,6 @@ namespace Genode {
 #define ESC_END
 #endif /* GENODE_RELEASE */
 
-/*
- * We're using heavy CPP wizardry here to prevent compiler errors after macro
- * expansion. Each macro works as follows:
- *
- * - Support one format string plus zero or more arguments.
- * - Put all static strings (including the format string) in the first argument
- *   of the call to printf() and let the compiler merge them.
- * - Append the function name (magic static string variable) as first argument.
- * - (Optionally) append the arguments to the macro with ", ##__VA_ARGS__". CPP
- *   only appends the comma and arguments if __VA__ARGS__ is not empty,
- *   otherwise nothing (not even the comma) is appended.
- */
-
 /**
  * Suppress debug messages in release version
  */
@@ -76,11 +63,24 @@ namespace Genode {
 
 /**
  * Print debug message with function name
+ *
+ * We're using heavy CPP wizardry here to prevent compiler errors after macro
+ * expansion. Each macro works as follows:
+ *
+ * - Support one format string plus zero or more arguments.
+ * - Put all static strings (including the format string) in the first argument
+ *   of the call to printf() and let the compiler merge them.
+ * - Append the function name (magic static string variable) as first argument.
+ * - (Optionally) append the arguments to the macro with ", ##__VA_ARGS__". CPP
+ *   only appends the comma and arguments if __VA__ARGS__ is not empty,
+ *   otherwise nothing (not even the comma) is appended.
  */
 #define PDBG(fmt, ...) \
-	if (DO_PDBG) \
-		Genode::printf("%s: " ESC_DBG fmt ESC_END "\n", \
-		               __PRETTY_FUNCTION__, ##__VA_ARGS__ )
+	do { \
+		if (DO_PDBG) \
+			Genode::printf("%s: " ESC_DBG fmt ESC_END "\n", \
+			               __PRETTY_FUNCTION__, ##__VA_ARGS__ ); \
+	} while (0)
 
 /**
  * Print log message
@@ -98,8 +98,10 @@ namespace Genode {
  * Print warning message
  */
 #define PWRN(fmt, ...) \
-	if (DO_PWRN) \
-		Genode::printf(ESC_WRN fmt ESC_END "\n", ##__VA_ARGS__ )
+	do { \
+		if (DO_PWRN) \
+			Genode::printf(ESC_WRN fmt ESC_END "\n", ##__VA_ARGS__ ); \
+	} while (0)
 
 /**
  * Print error message