Compiler error message for calling std.debug.print with the wrong format string doesn't include the line number of the error, even when compiling with -freference-trace

[orvly]

Zig Version

0.12.0-dev.3126+136d7c213

Steps to Reproduce and Observed Output

Zig Version 0.12.0-dev

Steps to Reproduce and Observed Output

When you call std.debug.print with too few arguments:

pub fn main() void {
 const myconst : i32 = 42;
 std.debug.print("Hello {s}\n", .{myconst});
}

The error message doesn't include the line number, even when compiling with -freference-trace

In #18485 , which looks very similar, @xdBronch says that is fixed in master, and I'm on the latest version, AFAIK.

Command line

zig run main.zig -freference-trace

Output Notice how nowhere in this output is the actual source line in my own code specified.

D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\fmt.zig:470:5: error: invalid format string 's' for type 'i32'
    @compileError("invalid format string '" ++ fmt ++ "' for type '" ++ @typeName(@TypeOf(value)) ++ "'");
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
referenced by:
    formatIntValue__anon_8030: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\fmt.zig:752:24
    formatValue__anon_7838: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\fmt.zig:704:52
    formatType__anon_6885: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\fmt.zig:498:31
    format__anon_3722: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\fmt.zig:184:23
    print__anon_3693: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\io\Writer.zig:23:26
    print: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\io.zig:322:47
    dumpStackTraceFromBase: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:284:19
    dumpSegfaultInfoWindows: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2707:5
    handleSegfaultWindowsExtra: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2679:17
    handleSegfaultWindows: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2651:45
    attachSegfaultHandler: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2540:83
    maybeEnableSegfaultHandler: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2521:18
    WinStartup: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\start.zig:348:14

Note: I'm new to zig (just started learning today), so I might be misunderstanding something.

Expected Output

I'd expect the error message to include the line number of the offending statement.

[RossComputerGuy]

The error trace does say where it comes from, strange that it says its with the segfault handling.

    dumpStackTraceFromBase: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:284:19
    dumpSegfaultInfoWindows: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2707:5
    handleSegfaultWindowsExtra: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2679:17
    handleSegfaultWindows: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2651:45
    attachSegfaultHandler: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2540:83
    maybeEnableSegfaultHandler: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\debug.zig:2521:18
    WinStartup: D:\zig\zig-windows-x86_64-0.12.0-dev.3126+136d7c213\lib\std\start.zig:348:14

[xdBronch]

i saw this happen to someone the other day where it points at the segfault handler, i have no idea why thats happening but im pretty sure its fairly recent

[rohlem]

looks similar to #18900 to me

[RossComputerGuy]

@rohlem That one occurs by calling logging methods, this is occurring in the stack trace printing code in std.

[rohlem]

@RossComputerGuy Right, and as far as I can see both cases trigger the @compileError at std/fmt.zig:470, "invalid format string 's' for type '<other>'". I wanted to link the issues together to suggest re-testing both against a fix (which I assume may apply to /fix both issues).

[gwenzek]

Proposed a solution in #20292 : tweak fmt.format to log the culprit formatting string.

[gwenzek]

This is probably caused by https://github.com/ziglang/zig/issues/18900

[WillLillis]

Running the sample program with -freference-trace has the line number from main.zig included again:

❯ zig run src/main.zig -freference-trace
/home/lillis/zig/lib/std/fmt.zig:483:5: error: invalid format string 's' for type 'i32'
    @compileError("invalid format string '" ++ fmt ++ "' for type '" ++ @typeName(@TypeOf(value)) ++ "'");
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
referenced by:
    formatIntValue__anon_8891: /home/lillis/zig/lib/std/fmt.zig:765:24
    formatValue__anon_8614: /home/lillis/zig/lib/std/fmt.zig:717:52
    formatType__anon_8478: /home/lillis/zig/lib/std/fmt.zig:511:31
    format__anon_7837: /home/lillis/zig/lib/std/fmt.zig:188:23
    print__anon_3748: /home/lillis/zig/lib/std/io/Writer.zig:24:26
    print__anon_3343: /home/lillis/zig/lib/std/io.zig:324:47
    main: src/main.zig:5:20
    posixCallMainAndExit: /home/lillis/zig/lib/std/start.zig:523:22
    _start: /home/lillis/zig/lib/std/start.zig:361:40
    comptime_0: /home/lillis/zig/lib/std/start.zig:99:54

[gwenzek]

thanks !

[yuyuasm]

const std = @import("std");

pub fn main() void {
    const myconst : i32 = 42;
    std.debug.print("Hello {d}\n", .{myconst});
}

你应该使用 {d}, 这是一个int !!!