Crash on a custom syntax file with a Swift shebang

[frkd-dev]

Description of the problem or steps to reproduce

Preamble
The Micro has syntax support for Swift language, but only when filenames end with the .swift extension. Unfortunately, it doesn't recognize a shebang #!/usr/bin/swift and no syntax highlighting as the result. The shebang is totally valid on macOS, as that's the official Swift interpreter.

Problem
I decided to create a custom syntax file ~/.config/micro/syntax/swift.yaml with the following content:

filetype: swift
detect:
    header: "#!/usr/bin/swift"

Now, whenever I create a new file, add a shebang #!/usr/bin/swift, and then save it, the editor crashes every time with the following output:

Micro encountered an error: runtime.errorString runtime error: invalid memory address or nil pointer dereference
runtime/panic.go:261 (0x1007a381c)
runtime/signal_unix.go:861 (0x1007a37e9)
github.com/zyedidia/micro/v2/pkg/highlight/parser.go:217 (0x100b53e9d)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:775 (0x100b5d504)
github.com/zyedidia/micro/v2/internal/buffer/save.go:219 (0x100b682a4)
github.com/zyedidia/micro/v2/internal/buffer/save.go:98 (0x100b98c20)
github.com/zyedidia/micro/v2/internal/action/actions.go:829 (0x100b98bf5)
github.com/zyedidia/micro/v2/internal/action/actions.go:765 (0x100b985a0)
github.com/zyedidia/micro/v2/internal/action/actions.go:775 (0x100b9861c)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:545 (0x100ba390c)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:150 (0x100ba1f8c)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:32 (0x100ba1d70)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:528 (0x100ba368c)
github.com/zyedidia/micro/v2/internal/action/bufpane.go:444 (0x100ba3200)
github.com/zyedidia/micro/v2/internal/action/tab.go:269 (0x100bb1e3c)
github.com/zyedidia/micro/v2/internal/action/tab.go:139 (0x100bb13e8)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:476 (0x100be8714)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:394 (0x100be7f98)
runtime/internal/atomic/types.go:194 (0x10078e15c)
runtime/asm_arm64.s:1197 (0x1007c0f04)

If I open an already existing file with the same shebang, I get a crash with the following output:

Micro encountered an error: runtime.errorString runtime error: invalid memory address or nil pointer dereference
runtime/panic.go:261 (0x104e9b81c)
runtime/signal_unix.go:861 (0x104e9b7e9)
github.com/zyedidia/micro/v2/pkg/highlight/parser.go:217 (0x10524be9d)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:775 (0x105255504)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:392 (0x105253088)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:261 (0x105251f20)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:203 (0x1052df474)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:331 (0x1052dfc10)
runtime/internal/atomic/types.go:194 (0x104e8615c)
runtime/asm_arm64.s:1197 (0x104eb8f04)

Both stacktraces are pointing at this line.

Specifications

The micro is installed using macports.

Version: 2.0.13
Commit hash: unknown
Compiled on January 12, 2024

[JoeKar]

You should better start by copying something present to your local config folder (e.g. https://github.com/zyedidia/micro/blob/master/runtime/syntax/awk.yaml). The problem is that you define your syntax file without top level rules (it's mandatory). Without it there wouldn't be anything to highlight anyway.

PS:
I plan to refactor the code to transform rules to be optionally...at for nesting in regions. For the top level rules indeed some more robustness and error log would be helpful.

[frkd-dev]

Okay, I misunderstood the intention of syntax files, and they should be full-fledged highlighting rules. I'll remove my invalid syntax file, as I don't want to completely override the original rules.

Could you kindly add a shebang to the swift.yaml then? I would do that, but I don't think this one-liner deserves a PR.

[JoeKar]

Oh, most probably misunderstood you too. You can workaround the current situation by using the following custom ~/.config/micro/syntax/swift.yaml:

filetype: swift

detect:
    filename: "\\.swift$"
    header: "^#!.*bin/(env +)?swift( |$)"

rules:
    - include: "swift"

It includes the rules of the builtin definition, but extends them with the own header definition.

I would do that, but I don't think this one-liner deserves a PR.

Sure you can, you've the example present above. 😉

[frkd-dev]

Opened a PR #3451

[dmaluka]

FWIW, the crash was fixed by #3213. The fix is present in 2.0.14.

[JoeKar]

Ah, right. Already forgot this. 👍