`lezer-generator` errors/warnings contain 1-based lines and 0-based columns

martijnwalraven · August 31, 2025, 6:23am

I’m not sure whether this is an oversight or expected behavior, but the errors/warnings from lezer-generator seem to contain 1-based lines and 0-based columns as part of their message. This can lead to misleading context with tools that expect both to be 1-based (e.g. in a VS Code problem matcher).

I think changing either lineInfo or message would fix this. If the ch computed in lineInfo is meant to be 0-based, it would be helpful to at least adjust the message to contain 1-based lines and columns.

github.com/lezer-parser/generator

src/parse.ts

5ebf7e208


      
          lineInfo(pos: number) {
            for (let line = 1, cur = 0;;) {
              let next = this.string.indexOf("\n", cur)
              if (next > -1 && next < pos) {
                ++line
                cur = next + 1
              } else {
                return {line, ch: pos - cur}
              }
            }
          }
          
          message(msg: string, pos: number = -1): string {
            let posInfo = this.fileName || ""
            if (pos > -1) {
              let info = this.lineInfo(pos)
              posInfo += (posInfo ? " " : "") + info.line + ":" + info.ch
            }
            return posInfo ? msg + ` (${posInfo})` : msg
          }

marijn · September 1, 2025, 3:34pm

This is expected behavior. CodeMirror works the same way, as do many tools that refer to lines/columns.