object.Exception at std/stdio.d(1321): Enforcement failed - I must be doing something wrong?

[Colin Grogan]

Hi all,

I've done this a million times (I thought!) but I'm getting a 
strange error I cant figure out.

The code:

void writeMsg(string msg){
       logFile.writeln(msg);
}

is failing with this error:

object.Exception at std/stdio.d(1321): Enforcement failed
----------------
./tester(pure @safe bool 
std.exception.enforce!(bool).enforce(bool, lazy const(char)[], 
immutable(char)[], ulong)+0x6b) [0x49a343]
./tester(ref std.stdio.File.LockingTextWriter 
std.stdio.File.LockingTextWriter.__ctor(ref std.stdio.File)+0x59) 
[0x4ce019]
./tester(@property std.stdio.File.LockingTextWriter 
std.stdio.File.lockingTextWriter()+0x29) [0x4ce179]
./tester(void std.stdio.File.write!(immutable(char)[], 
char).write(immutable(char)[], char)+0x69) [0x49b931]
./tester(void 
std.stdio.File.writeln!(immutable(char)[]).writeln(immutable(char)[])+0x67) 
[0x49b8bf]
./tester(void utils.log.Logger.writeMsg(immutable(char)[])+0x29) 
[0x494631]
./tester(void utils.log.Logger.log(utils.log.LogLevel, 
immutable(char)[])+0xa5) [0x4946dd]
./tester(void utils.log.Logger.logDebug(immutable(char)[])+0xa2) 
[0x49455a]
./tester(_Dmain+0x52) [0x4a3862]
./tester(extern (C) int rt.dmain2._d_run_main(int, char**, extern 
(C) int function(char[][])*).void runMain()+0x18) [0x4bf79c]
./tester(extern (C) int rt.dmain2._d_run_main(int, char**, extern 
(C) int function(char[][])*).void tryExec(scope void 
delegate())+0x2a) [0x4bf2ce]
./tester(extern (C) int rt.dmain2._d_run_main(int, char**, extern 
(C) int function(char[][])*).void runAll()+0x40) [0x4bf7ec]
./tester(extern (C) int rt.dmain2._d_run_main(int, char**, extern 
(C) int function(char[][])*).void tryExec(scope void 
delegate())+0x2a) [0x4bf2ce]
./tester(_d_run_main+0x1ae) [0x4bf28a]
./tester(main+0x17) [0x4bf0d7]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xed) 
[0x7f6bcc3f176d]


Also, I'm creating the logFile variable as follows:
File logFile = File(fileName, "w");

If ye need the code around it I'll be glad to post it, but the 
logFile.writeln(msg) is the specific line it breaks on. If I 
comment that out all is good.
It writes to the file once, and next time I call the function it 
fails.

My guess is the lock on the file isn't releasing after the first 
write?