Diagnostics

The compiler reports problems as diagnostics, each with a code. Every code has a page with its messages and a program that gives it.

Format:

<file>:<line>:<col>: error TP<code>: <message>
  help: <optional hint>

• Diagnostics are written to stderr.

• Lines and columns are 1-based. Columns count Unicode code points.

• Each compiler stage runs only if the stages before it reported no errors: lexing (§1), then parsing (§2), then type checking. This keeps one mistake from cascading into spurious errors in later stages.

• <file> is the source path exactly as given on the command line.

• Warnings (TP0300, TP0301, TP0302 and TP0303) print as <file>:<line>:<col>: warning TP<code>: <message>. They don’t stop compilation or change the exit code. They’re printed with the type checker’s errors, before the program runs.

Exit codes:

• 0 success
• 1 compile error
• 2 usage or I/O error (bad arguments, file not found)
• 101 runtime panic

Code	Kind	Meaning
TP0001	error	tab in indentation
TP0002	error	dedent doesn’t match any outer indentation level
TP0003	error	unterminated string
TP0004	error	invalid character
TP0005	error	invalid escape sequence
TP0006	error	invalid f-string
TP0007	error	invalid number literal
TP0100	error	syntax error: expected X, found Y (including 'yield' needs a value, M31, until M42 allowed a bare yield)
TP0200	error	type mismatch
TP0201	error	undefined name
TP0202	error	cannot assign to let binding
TP0203	error	optional used without narrowing (expected T, got T?)
TP0204	error	non-exhaustive match (missing: …)
TP0205	error	condition must be bool
TP0206	error	cannot infer type of empty collection
TP0207	error	shadowing an outer binding
TP0208	error	not all paths return a value
TP0209	error	wrong number of arguments
TP0210	error	unknown field or method
TP0211	error	function references a top-level variable
TP0212	error	chained comparison not supported
TP0213	error	nested optional
TP0214	error	duplicate definition
TP0215	error	break/continue outside loop, return outside function, a bare raise outside except, return/break/continue in finally, or a misplaced yield or await
TP0216	error	ambiguous enum variant; qualify it
TP0217	error	const initializer is not a constant expression
TP0218	error	keyword argument not accepted
TP0219	error	generic instantiation too deep (polymorphic recursion)
TP0220	error	invalid type parameter constraint or bound
TP0221	error	module not found
TP0222	error	top-level statement in an imported module, or in a library’s main file or an extension module
TP0223	error	nested function with type parameters
TP0224	error	invalid decorator
TP0225	error	invalid class definition
TP0226	error	object used before it is fully initialized
TP0227	error	missing or unneeded @override
TP0228	error	incompatible override
TP0229	error	protocol used as a type
TP0230	error	recursive type alias
TP0231	error	.NET member or type that Taipan can’t use
TP0232	error	ambiguous .NET overload
TP0233	error	can’t be used in a native program
TP0234	error	abstract class instantiated
TP0235	error	awaitable never awaited
TPN001	error	an SDK project’s main file is missing
TPN002	error	an SDK project’s taipan.json lists references or packages
TP0300	warning	warning: unreachable code (a statement, match arm or except clause)
TP0301	warning	warning: broad except clause discards the exception
TP0302	warning	warning: a library’s or extension module’s definition can’t be exported
TP0303	warning	warning: a test_ function that can’t be run as a test