1 files changed, 22 insertions, 0 deletions
diff --git a/src/look.zig b/src/look.zig
index 36eae75c..de51804d 100644
--- a/src/look.zig
+++ b/src/look.zig
@@ -1233,6 +1233,25 @@ fn missedLine(p: *Pardes, id: usize, path: []const u8, line: anytype) void {
     missed(p, id, "{s} has no line {d}", .{ missText(path, &cut), line });
 }
 
+/// Whether `:line:col`, `:line:col-col` or `:line:col-line:col` after a
+/// path names a column 0, which parsePathLine reads as no column.
+fn zeroColumn(rest: []const u8) bool {
+    var fields = std.mem.splitScalar(u8, rest, ':');
+    _ = fields.next(); // before the first ':'
+    _ = fields.next() orelse return false; // the line
+    const col = fields.next() orelse return false;
+    var ends = std.mem.splitScalar(u8, col, '-');
+    if (std.mem.eql(u8, ends.next().?, "0")) return true;
+    if (ends.next()) |end| if (std.mem.eql(u8, end, "0")) return true;
+    if (fields.next()) |end_col| if (std.mem.eql(u8, end_col, "0")) return true;
+    return false;
+}
+
+test "a zero column after a path is found, in every spelling a look takes" {
+    for ([_][]const u8{ ":3:0", ":3:0-4", ":3:2-0", ":3:2-5:0" }) |rest| try std.testing.expect(zeroColumn(rest));
+    for ([_][]const u8{ "", ":3", ":3:1", ":3:2-5", ":3:2-5:7", ":30:10" }) |rest| try std.testing.expect(!zeroColumn(rest));
+}
+
 fn missed(p: *Pardes, id: usize, comptime fmt: []const u8, args: anytype) void {
     p.look_missed = true;
     var said: [miss_path_cap + 64]u8 = undefined;
@@ -1504,6 +1523,9 @@ pub fn lookAt(p: *Pardes, id: usize, operand: []const u8) void {
     // the colon, evaluated in that file from its dot (openfile, look.c:675).
     if (addressed(trimmed)) |ad| return lookAddress(p, id, ad.path, ad.expr);
     const pl = parsePathLine(trimmed);
+    // `file:3:0`: columns count from 1, as addr's do, and a zero is refused
+    // in addr's words rather than taken as no column.
+    if (pl.at.line != 0 and zeroColumn(trimmed[pl.path.len..])) return p.reportFailure(id, @import("ninep/addr.zig").e_col_zero);
     if (comptime pdf_enabled) if (pane.hasPdf()) clearNavigationSelection(p, pane);
     if (comptime pdf_enabled) if (panes.Pdf.lookSection(p, id, pl.path, pl.at)) return;
     var realbuf: [4096]u8 = undefined;