Index: Makefile.msc
==================================================================
--- Makefile.msc
+++ Makefile.msc
@@ -137,10 +137,17 @@
 # Set this to non-0 to use the Win32 native heap subsystem.
 #
 !IFNDEF WIN32HEAP
 WIN32HEAP = 0
 !ENDIF
+
+# Set this to non-0 to enable OSTRACE() macros, which can be useful when
+# debugging.
+#
+!IFNDEF OSTRACE
+OSTRACE = 0
+!ENDIF
 
 # Set this to one of the following values to enable various debugging
 # features.  Each level includes the debugging options from the previous
 # levels.  Currently, the recognized values for DEBUG are:
 #
@@ -479,13 +486,13 @@
 !IF $(DEBUG)>2
 TCC = $(TCC) -DSQLITE_DEBUG
 RCC = $(RCC) -DSQLITE_DEBUG
 !ENDIF
 
-!IF $(DEBUG)>4
-TCC = $(TCC) -DSQLITE_DEBUG_OS_TRACE=1
-RCC = $(RCC) -DSQLITE_DEBUG_OS_TRACE=1
+!IF $(DEBUG)>4 || $(OSTRACE)!=0
+TCC = $(TCC) -DSQLITE_FORCE_OS_TRACE=1 -DSQLITE_DEBUG_OS_TRACE=1
+RCC = $(RCC) -DSQLITE_FORCE_OS_TRACE=1 -DSQLITE_DEBUG_OS_TRACE=1
 !ENDIF
 
 !IF $(DEBUG)>5
 TCC = $(TCC) -DSQLITE_ENABLE_IOTRACE
 RCC = $(RCC) -DSQLITE_ENABLE_IOTRACE

Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -53,10 +53,22 @@
 ** zero if and only if SQLite was compiled with mutexing code omitted due to
 ** the SQLITE_THREADSAFE compile-time option being set to 0.
 */
 int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
 
+/*
+** When compiling the test fixture or with debugging enabled (on Win32),
+** this variable being set to non-zero will cause OSTRACE macros to emit
+** extra diagnostic information.
+*/
+#ifdef SQLITE_HAVE_OS_TRACE
+# ifndef SQLITE_DEBUG_OS_TRACE
+#   define SQLITE_DEBUG_OS_TRACE 0
+# endif
+  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
+#endif
+
 #if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
 /*
 ** If the following function pointer is not NULL and if
 ** SQLITE_ENABLE_IOTRACE is enabled, then messages describing
 ** I/O active are written using this function.  These messages
@@ -1192,11 +1204,11 @@
 
 /*
 ** Return a static string containing the name corresponding to the error code
 ** specified in the argument.
 */
-#if (defined(SQLITE_DEBUG) && SQLITE_OS_WIN) || defined(SQLITE_TEST)
+#if defined(SQLITE_NEED_ERR_NAME)
 const char *sqlite3ErrName(int rc){
   const char *zName = 0;
   int i, origRc = rc;
   for(i=0; i<2 && zName==0; i++, rc &= 0xff){
     switch( rc ){

Index: src/os_common.h
==================================================================
--- src/os_common.h
+++ src/os_common.h
@@ -27,20 +27,10 @@
 */
 #ifdef MEMORY_DEBUG
 # error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
 #endif
 
-#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
-# ifndef SQLITE_DEBUG_OS_TRACE
-#   define SQLITE_DEBUG_OS_TRACE 0
-# endif
-  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
-# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
-#else
-# define OSTRACE(X)
-#endif
-
 /*
 ** Macros for performance tracing.  Normally turned off.  Only works
 ** on i486 hardware.
 */
 #ifdef SQLITE_PERFORMANCE_TRACE

Index: src/os_unix.c
==================================================================
--- src/os_unix.c
+++ src/os_unix.c
@@ -639,11 +639,11 @@
   return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
 }
 #endif
 
 
-#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+#ifdef SQLITE_HAVE_OS_TRACE
 /*
 ** Helper function for printing out trace information from debugging
 ** binaries. This returns the string representation of the supplied
 ** integer lock-type.
 */

Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -2755,11 +2755,11 @@
   ** Used only when SQLITE_NO_SYNC is not defined.
    */
   BOOL rc;
 #endif
 #if !defined(NDEBUG) || !defined(SQLITE_NO_SYNC) || \
-    (defined(SQLITE_TEST) && defined(SQLITE_DEBUG))
+    defined(SQLITE_HAVE_OS_TRACE)
   /*
   ** Used when SQLITE_NO_SYNC is not defined and by the assert() and/or
   ** OSTRACE() macros.
    */
   winFile *pFile = (winFile*)id;
@@ -3432,11 +3432,11 @@
   DWORD lastErrno;           /* The Windows errno from the last I/O error */
 
   int nRef;                  /* Number of winShm objects pointing to this */
   winShm *pFirst;            /* All winShm objects pointing to this */
   winShmNode *pNext;         /* Next in list of all winShmNode objects */
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   u8 nextShmId;              /* Next available winShm.id value */
 #endif
 };
 
 /*
@@ -3463,11 +3463,11 @@
   winShmNode *pShmNode;      /* The underlying winShmNode object */
   winShm *pNext;             /* Next winShm with the same winShmNode */
   u8 hasMutex;               /* True if holding the winShmNode mutex */
   u16 sharedMask;            /* Mask of shared locks held */
   u16 exclMask;              /* Mask of exclusive locks held */
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   u8 id;                     /* Id of this connection with its winShmNode */
 #endif
 };
 
 /*
@@ -3654,11 +3654,11 @@
     if( rc ) goto shm_open_err;
   }
 
   /* Make the new connection a child of the winShmNode */
   p->pShmNode = pShmNode;
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   p->id = pShmNode->nextShmId++;
 #endif
   pShmNode->nRef++;
   pDbFd->pShm = p;
   winShmLeaveMutex();

Index: src/printf.c
==================================================================
--- src/printf.c
+++ src/printf.c
@@ -1057,11 +1057,11 @@
     renderLogMsg(iErrCode, zFormat, ap);
     va_end(ap);
   }
 }
 
-#if defined(SQLITE_DEBUG)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
 /*
 ** A version of printf() that understands %lld.  Used for debugging.
 ** The printf() built into some versions of windows does not understand %lld
 ** and segfaults if you give it a long long int.
 */

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -360,10 +360,36 @@
 #else
 # define ALWAYS(X)      (X)
 # define NEVER(X)       (X)
 #endif
 
+/*
+** Declarations used for tracing the operating system interfaces.
+*/
+#if defined(SQLITE_FORCE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+  extern int sqlite3OSTrace;
+# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+# define SQLITE_HAVE_OS_TRACE
+#else
+# define OSTRACE(X)
+# undef  SQLITE_HAVE_OS_TRACE
+#endif
+
+/*
+** Is the sqlite3ErrName() function needed in the build?  Currently,
+** it is needed by "mutex_w32.c" (when debugging), "os_win.c" (when
+** OSTRACE is enabled), and by several "test*.c" files (which are
+** compiled using SQLITE_TEST).
+*/
+#if defined(SQLITE_HAVE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+# define SQLITE_NEED_ERR_NAME
+#else
+# undef  SQLITE_NEED_ERR_NAME
+#endif
+
 /*
 ** Return true (non-zero) if the input is an integer that is too large
 ** to fit in 32-bits.  This macro is used inside of various testcase()
 ** macros to verify that we have tested SQLite for large-file support.
 */
@@ -3144,11 +3170,11 @@
 void sqlite3VXPrintf(StrAccum*, u32, const char*, va_list);
 void sqlite3XPrintf(StrAccum*, u32, const char*, ...);
 char *sqlite3MPrintf(sqlite3*,const char*, ...);
 char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
 char *sqlite3MAppendf(sqlite3*,char*,const char*,...);
-#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   void sqlite3DebugPrintf(const char*, ...);
 #endif
 #if defined(SQLITE_TEST)
   void *sqlite3TestTextToPtr(const char*);
 #endif
@@ -3491,11 +3517,11 @@
 void sqlite3Error(sqlite3*,int);
 void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
 u8 sqlite3HexToInt(int h);
 int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
 
-#if defined(SQLITE_TEST) 
+#if defined(SQLITE_NEED_ERR_NAME)
 const char *sqlite3ErrName(int);
 #endif
 
 const char *sqlite3ErrStr(int);
 int sqlite3ReadSchema(Parse *pParse);