Diagnostic codes¶

Every compiler diagnostic carries a four-character prefix plus a four-digit number: GP for the parser / lexer, GR for name resolution, GT for the type checker, GM for match exhaustiveness, GL for lint framework, GK for the package manager. Use gos explain <code> for the interactive version. This page is auto-generated from the catalogue in xtask/src/main.rs; hand edits are overwritten by cargo xtask docs-diagnostics.

Code	Phase	Title
GP0001	Parser	unexpected token
GP0002	Parser	unexpected end of input
GP0003	Parser	unterminated delimiter
GP0004	Parser	chained comparison without parentheses
GR0001	Resolve	unresolved name
GR0002	Resolve	wrong namespace
GR0003	Resolve	duplicate item
GR0004	Resolve	duplicate import
GT0001	Types	type mismatch
GT0002	Types	unresolved method
GT0003	Types	unresolved operator
GT0004	Match exhaustiveness	non-exhaustive match
GT0005	Types	non-primitive cast
GK0001	Package manager	manifest parse error

GP0001 ¶

Parser — unexpected token

The parser saw a token where it expected a different one. Check for missing punctuation, an unmatched delimiter, or an out-of-place keyword.

GP0002 ¶

Parser — unexpected end of input

The parser reached end-of-file in the middle of a construct. Finish the expression, statement, or item — or remove it.

GP0003 ¶

Parser — unterminated delimiter

A balanced construct (block, tuple, array, string literal) was left unterminated. Add the matching closing delimiter.

GP0004 ¶

Parser — chained comparison without parentheses

Comparison operators like == / != / < are not associative. Parenthesise the operands: (a == b) && (b == c).

GR0001 ¶

Resolve — unresolved name

A name used in source could not be resolved to a declaration. Check the spelling, whether a use brings the name into scope, and whether the item is visible at this location.

GR0002 ¶

Resolve — wrong namespace

A name was resolved to the wrong namespace (value vs. type). Check the declaration and the spelling.

GR0003 ¶

Resolve — duplicate item

Two items in the same module share a name. Rename one of them or move it into a distinct mod.

GR0004 ¶

Resolve — duplicate import

The same path was imported twice in the same use list. Drop the duplicate.

GT0001 ¶

Types — type mismatch

The type checker could not reconcile two types it expected to match. The primary label shows the location of the mismatch; the note: line names the conflicting types.

GT0002 ¶

Types — unresolved method

The type checker could not find a method with the supplied name on the receiver type. Check for a typo, a missing use, or a trait impl that lives in an unreachable module.

GT0003 ¶

Types — unresolved operator

The operator is not defined for the operand types. Check the operand types and use the correct operator.

GT0004 ¶

Match exhaustiveness — non-exhaustive match

A match expression does not cover every possible value. Add an arm for the pattern(s) listed under help:.

GT0005 ¶

Types — non-primitive cast

The as cast is restricted to a whitelist: numeric ↔ numeric, bool/char → integer, u8 → char, and same-type no-ops. Struct / enum / String sources are rejected. Use a conversion method when you need serialisation; as does not run code.

GK0001 ¶

Package manager — manifest parse error

The package manifest (gos.toml) could not be parsed. Check the TOML syntax and required fields.