Using commas wrong in a type ignore makes there be an error code in there that is the empty string #20038
Description
Expected behavior:
[case testErrorCodeWarnUnusedIgnores9_testUnusedIgnoreSloppyFormattingNotEmptyBrackets]
# flags: --warn-unused-ignores
1 + "ok" + "ok".foo # type: ignore[ operator,attr-defined]
1 + "ok" + "ok".foo # type: ignore[ ,operator,attr-defined] # E: Unused "type: ignore" comment [unused-ignore]
1 + "ok" + "ok".foo # type: ignore[ operator,attr-defined,] # E: Unused "type: ignore" comment [unused-ignore]
1 + "ok" + "ok".foo # type: ignore[ operator,attr-defined,,] # E: Unused "type: ignore" comment [unused-ignore]
[case testErrorCodeWarnUnusedIgnores10_testUnusedIgnoreSloppyFormattingEmptyBrackets]
# flags: --warn-unused-ignores
1+1 # type: ignore # E: Unused "type: ignore" comment [unused-ignore]
1+1 # type: ignore[] # E: Unused "type: ignore" comment [unused-ignore]
1+1 # type: ignore[ ] # E: Unused "type: ignore" comment [unused-ignore]
1+1 # type: ignore[,,, ] # E: Unused "type: ignore" comment [unused-ignore]Actual behavior:
When there is a trailing comma, a leading comma, or other comma abuse, the error is Unused "type: ignore[]" comment instead, because the empty string error code still counts.
I could easily have suppressed this symptom at the site of the unused ignores warning, but this seems like something that should probably be fixed at the source, to avoid other almost-invisible erroneous behavior from popping up later.