diff options
Diffstat (limited to 'tvix/eval/src/errors.rs')
| -rw-r--r-- | tvix/eval/src/errors.rs | 1044 |
1 files changed, 1044 insertions, 0 deletions
diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs new file mode 100644 index 000000000000..a61d55aa21f8 --- /dev/null +++ b/tvix/eval/src/errors.rs @@ -0,0 +1,1044 @@ +use std::error; +use std::io; +use std::path::PathBuf; +use std::rc::Rc; +use std::str::Utf8Error; +use std::string::FromUtf8Error; +use std::sync::Arc; +use std::{fmt::Debug, fmt::Display, num::ParseIntError}; + +use codemap::{File, Span}; +use codemap_diagnostic::{ColorConfig, Diagnostic, Emitter, Level, SpanLabel, SpanStyle}; +use smol_str::SmolStr; +use xml::writer::Error as XmlError; + +use crate::spans::ToSpan; +use crate::value::{CoercionKind, NixString}; +use crate::{SourceCode, Value}; + +/// "CatchableErrorKind" errors -- those which can be detected by +/// `builtins.tryEval`. +/// +/// Note: this type is deliberately *not* incorporated as a variant +/// of ErrorKind, because then Result<Value,ErrorKind> would have +/// redundant representations for catchable errors, which would make +/// it too easy to handle errors incorrectly: +/// +/// - Ok(Value::Catchable(cek)) +/// - Err(ErrorKind::ThisVariantDoesNotExist(cek)) +/// +/// Because CatchableErrorKind is not a variant of ErrorKind, you +/// will often see functions which return a type like: +/// +/// Result<Result<T,CatchableErrorKind>,ErrorKind> +/// +/// ... where T is any type other than Value. This is unfortunate, +/// because Rust's magic `?`-syntax does not work on nested Result +/// values like this. +/// +/// TODO(amjoseph): investigate result<T,Either<CatchableErrorKind,ErrorKind>> +/// +#[derive(Clone, Debug)] +pub enum CatchableErrorKind { + Throw(String), + AssertionFailed, + /// Resolving a user-supplied angle brackets path literal failed in some way. + NixPathResolution(String), +} + +#[derive(Clone, Debug)] +pub enum ErrorKind { + /// These are user-generated errors through builtins. + Abort(String), + + DivisionByZero, + + DuplicateAttrsKey { + key: String, + }, + + /// Attempted to specify an invalid key type (e.g. integer) in a + /// dynamic attribute name. + InvalidAttributeName(Value), + + AttributeNotFound { + name: String, + }, + + /// Attempted to index into a list beyond its boundaries. + IndexOutOfBounds { + index: i64, + }, + + /// Attempted to call `builtins.tail` on an empty list. + TailEmptyList, + + TypeError { + expected: &'static str, + actual: &'static str, + }, + + Incomparable { + lhs: &'static str, + rhs: &'static str, + }, + + /// Resolving a user-supplied relative or home-relative path literal failed in some way. + RelativePathResolution(String), + + /// Dynamic keys are not allowed in some scopes. + DynamicKeyInScope(&'static str), + + /// Unknown variable in statically known scope. + UnknownStaticVariable, + + /// Unknown variable in dynamic scope (with, rec, ...). + UnknownDynamicVariable(String), + + /// User is defining the same variable twice at the same depth. + VariableAlreadyDefined(Span), + + /// Attempt to call something that is not callable. + NotCallable(&'static str), + + /// Infinite recursion encountered while forcing thunks. + InfiniteRecursion { + first_force: Span, + suspended_at: Option<Span>, + content_span: Option<Span>, + }, + + ParseErrors(Vec<rnix::parser::ParseError>), + + /// An error occured while executing some native code (e.g. a + /// builtin), and needs to be chained up. + NativeError { + gen_type: &'static str, + err: Box<Error>, + }, + + /// An error occured while executing Tvix bytecode, but needs to + /// be chained up. + BytecodeError(Box<Error>), + + /// Given type can't be coerced to a string in the respective context + NotCoercibleToString { + from: &'static str, + kind: CoercionKind, + }, + + /// The given string doesn't represent an absolute path + NotAnAbsolutePath(PathBuf), + + /// An error occurred when parsing an integer + ParseIntError(ParseIntError), + + // Errors specific to nested attribute sets and merges thereof. + /// Nested attributes can not be merged with an inherited value. + UnmergeableInherit { + name: SmolStr, + }, + + /// Nested attributes can not be merged with values that are not + /// literal attribute sets. + UnmergeableValue, + + /// Parse errors occured while importing a file. + ImportParseError { + path: PathBuf, + file: Arc<File>, + errors: Vec<rnix::parser::ParseError>, + }, + + /// Compilation errors occured while importing a file. + ImportCompilerError { + path: PathBuf, + errors: Vec<Error>, + }, + + /// I/O errors + IO { + path: Option<PathBuf>, + error: Rc<io::Error>, + }, + + /// Errors converting JSON to a value + FromJsonError(String), + + /// Nix value that can not be serialised to JSON. + NotSerialisableToJson(&'static str), + + /// Errors converting TOML to a value + FromTomlError(String), + + /// An unexpected argument was supplied to a function that takes formal parameters + UnexpectedArgument { + arg: NixString, + formals_span: Span, + }, + + /// Errors while serialising to XML. + Xml(Rc<XmlError>), + + /// Variant for errors that bubble up to eval from other Tvix + /// components. + TvixError(Rc<dyn error::Error>), + + /// Variant for code paths that are known bugs in Tvix (usually + /// issues with the compiler/VM interaction). + TvixBug { + msg: &'static str, + metadata: Option<Rc<dyn Debug>>, + }, + + /// Tvix internal warning for features triggered by users that are + /// not actually implemented yet, and without which eval can not + /// proceed. + NotImplemented(&'static str), + + /// Internal variant which should disappear during error construction. + WithContext { + context: String, + underlying: Box<ErrorKind>, + }, +} + +impl error::Error for Error { + fn source(&self) -> Option<&(dyn error::Error + 'static)> { + match &self.kind { + ErrorKind::NativeError { err, .. } | ErrorKind::BytecodeError(err) => err.source(), + ErrorKind::ParseErrors(err) => err.first().map(|e| e as &dyn error::Error), + ErrorKind::ParseIntError(err) => Some(err), + ErrorKind::ImportParseError { errors, .. } => { + errors.first().map(|e| e as &dyn error::Error) + } + ErrorKind::ImportCompilerError { errors, .. } => { + errors.first().map(|e| e as &dyn error::Error) + } + ErrorKind::IO { error, .. } => Some(error.as_ref()), + ErrorKind::Xml(error) => Some(error.as_ref()), + ErrorKind::TvixError(error) => Some(error.as_ref()), + _ => None, + } + } +} + +impl From<ParseIntError> for ErrorKind { + fn from(e: ParseIntError) -> Self { + Self::ParseIntError(e) + } +} + +impl From<Utf8Error> for ErrorKind { + fn from(_: Utf8Error) -> Self { + Self::NotImplemented("FromUtf8Error not handled: https://b.tvl.fyi/issues/189") + } +} + +impl From<FromUtf8Error> for ErrorKind { + fn from(_: FromUtf8Error) -> Self { + Self::NotImplemented("FromUtf8Error not handled: https://b.tvl.fyi/issues/189") + } +} + +impl From<XmlError> for ErrorKind { + fn from(err: XmlError) -> Self { + Self::Xml(Rc::new(err)) + } +} + +impl From<io::Error> for ErrorKind { + fn from(e: io::Error) -> Self { + ErrorKind::IO { + path: None, + error: Rc::new(e), + } + } +} + +impl From<serde_json::Error> for ErrorKind { + fn from(err: serde_json::Error) -> Self { + // Can't just put the `serde_json::Error` in the ErrorKind since it doesn't impl `Clone` + Self::FromJsonError(format!("error in JSON serialization: {err}")) + } +} + +impl From<toml::de::Error> for ErrorKind { + fn from(err: toml::de::Error) -> Self { + Self::FromTomlError(format!("error in TOML serialization: {err}")) + } +} + +#[derive(Clone, Debug)] +pub struct Error { + pub kind: ErrorKind, + pub span: Span, + pub contexts: Vec<String>, +} + +impl Error { + pub fn new(mut kind: ErrorKind, span: Span) -> Self { + let mut contexts = vec![]; + while let ErrorKind::WithContext { + context, + underlying, + } = kind + { + kind = *underlying; + contexts.push(context); + } + + Error { + kind, + span, + contexts, + } + } +} + +impl Display for ErrorKind { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + match &self { + ErrorKind::Abort(msg) => write!(f, "evaluation aborted: {}", msg), + + ErrorKind::DivisionByZero => write!(f, "division by zero"), + + ErrorKind::DuplicateAttrsKey { key } => { + write!(f, "attribute key '{}' already defined", key) + } + + ErrorKind::InvalidAttributeName(val) => write!( + f, + "found attribute name '{}' of type '{}', but attribute names must be strings", + val, + val.type_of() + ), + + ErrorKind::AttributeNotFound { name } => write!( + f, + "attribute with name '{}' could not be found in the set", + name + ), + + ErrorKind::IndexOutOfBounds { index } => { + write!(f, "list index '{}' is out of bounds", index) + } + + ErrorKind::TailEmptyList => write!(f, "'tail' called on an empty list"), + + ErrorKind::TypeError { expected, actual } => write!( + f, + "expected value of type '{}', but found a '{}'", + expected, actual + ), + + ErrorKind::Incomparable { lhs, rhs } => { + write!(f, "can not compare a {} with a {}", lhs, rhs) + } + + ErrorKind::RelativePathResolution(err) => { + write!(f, "could not resolve path: {}", err) + } + + ErrorKind::DynamicKeyInScope(scope) => { + write!(f, "dynamically evaluated keys are not allowed in {}", scope) + } + + ErrorKind::UnknownStaticVariable => write!(f, "variable not found"), + + ErrorKind::UnknownDynamicVariable(name) => write!( + f, + r#"variable '{}' could not be found + +Note that this occured within a `with`-expression. The problem may be related +to a missing value in the attribute set(s) included via `with`."#, + name + ), + + ErrorKind::VariableAlreadyDefined(_) => write!(f, "variable has already been defined"), + + ErrorKind::NotCallable(other_type) => { + write!( + f, + "only functions and builtins can be called, but this is a '{}'", + other_type + ) + } + + ErrorKind::InfiniteRecursion { .. } => write!(f, "infinite recursion encountered"), + + // Errors themselves ignored here & handled in Self::spans instead + ErrorKind::ParseErrors(_) => write!(f, "failed to parse Nix code:"), + + ErrorKind::NativeError { gen_type, .. } => { + write!(f, "while evaluating this as native code ({})", gen_type) + } + + ErrorKind::BytecodeError(_) => write!(f, "while evaluating this Nix code"), + + ErrorKind::NotCoercibleToString { kind, from } => { + let kindly = match kind { + CoercionKind::Strong => "strongly", + CoercionKind::Weak => "weakly", + }; + + let hint = if *from == "set" { + ", missing a `__toString` or `outPath` attribute" + } else { + "" + }; + + write!(f, "cannot ({kindly}) coerce {from} to a string{hint}") + } + + ErrorKind::NotAnAbsolutePath(given) => { + write!( + f, + "string '{}' does not represent an absolute path", + given.to_string_lossy() + ) + } + + ErrorKind::ParseIntError(err) => { + write!(f, "invalid integer: {}", err) + } + + ErrorKind::UnmergeableInherit { name } => { + write!( + f, + "cannot merge a nested attribute set into the inherited entry '{}'", + name + ) + } + + ErrorKind::UnmergeableValue => { + write!( + f, + "nested attribute sets or keys can only be merged with literal attribute sets" + ) + } + + // Errors themselves ignored here & handled in Self::spans instead + ErrorKind::ImportParseError { path, .. } => { + write!( + f, + "parse errors occured while importing '{}'", + path.to_string_lossy() + ) + } + + ErrorKind::ImportCompilerError { path, .. } => { + writeln!( + f, + "compiler errors occured while importing '{}'", + path.to_string_lossy() + ) + } + + ErrorKind::IO { path, error } => { + write!(f, "I/O error: ")?; + if let Some(path) = path { + write!(f, "{}: ", path.display())?; + } + write!(f, "{error}") + } + + ErrorKind::FromJsonError(msg) => { + write!(f, "Error converting JSON to a Nix value: {msg}") + } + + ErrorKind::NotSerialisableToJson(_type) => { + write!(f, "a {} cannot be converted to JSON", _type) + } + + ErrorKind::FromTomlError(msg) => { + write!(f, "Error converting TOML to a Nix value: {msg}") + } + + ErrorKind::UnexpectedArgument { arg, .. } => { + write!( + f, + "Unexpected argument `{}` supplied to function", + arg.as_str() + ) + } + + ErrorKind::Xml(error) => write!(f, "failed to serialise to XML: {error}"), + + ErrorKind::TvixError(inner_error) => { + write!(f, "{inner_error}") + } + + ErrorKind::TvixBug { msg, metadata } => { + write!(f, "Tvix bug: {}", msg)?; + + if let Some(metadata) = metadata { + write!(f, "; metadata: {:?}", metadata)?; + } + + Ok(()) + } + + ErrorKind::NotImplemented(feature) => { + write!(f, "feature not yet implemented in Tvix: {}", feature) + } + + ErrorKind::WithContext { .. } => { + panic!("internal ErrorKind::WithContext variant leaked") + } + } + } +} + +impl Display for Error { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + write!(f, "{}", self.kind) + } +} + +pub type EvalResult<T> = Result<T, Error>; + +/// Human-readable names for rnix syntaxes. +fn name_for_syntax(syntax: &rnix::SyntaxKind) -> &'static str { + match syntax { + rnix::SyntaxKind::TOKEN_COMMENT => "a comment", + rnix::SyntaxKind::TOKEN_WHITESPACE => "whitespace", + rnix::SyntaxKind::TOKEN_ASSERT => "`assert`-keyword", + rnix::SyntaxKind::TOKEN_ELSE => "`else`-keyword", + rnix::SyntaxKind::TOKEN_IN => "`in`-keyword", + rnix::SyntaxKind::TOKEN_IF => "`if`-keyword", + rnix::SyntaxKind::TOKEN_INHERIT => "`inherit`-keyword", + rnix::SyntaxKind::TOKEN_LET => "`let`-keyword", + rnix::SyntaxKind::TOKEN_OR => "`or`-keyword", + rnix::SyntaxKind::TOKEN_REC => "`rec`-keyword", + rnix::SyntaxKind::TOKEN_THEN => "`then`-keyword", + rnix::SyntaxKind::TOKEN_WITH => "`with`-keyword", + rnix::SyntaxKind::TOKEN_L_BRACE => "{", + rnix::SyntaxKind::TOKEN_R_BRACE => "}", + rnix::SyntaxKind::TOKEN_L_BRACK => "[", + rnix::SyntaxKind::TOKEN_R_BRACK => "]", + rnix::SyntaxKind::TOKEN_ASSIGN => "=", + rnix::SyntaxKind::TOKEN_AT => "@", + rnix::SyntaxKind::TOKEN_COLON => ":", + rnix::SyntaxKind::TOKEN_COMMA => "`,`", + rnix::SyntaxKind::TOKEN_DOT => ".", + rnix::SyntaxKind::TOKEN_ELLIPSIS => "...", + rnix::SyntaxKind::TOKEN_QUESTION => "?", + rnix::SyntaxKind::TOKEN_SEMICOLON => ";", + rnix::SyntaxKind::TOKEN_L_PAREN => "(", + rnix::SyntaxKind::TOKEN_R_PAREN => ")", + rnix::SyntaxKind::TOKEN_CONCAT => "++", + rnix::SyntaxKind::TOKEN_INVERT => "!", + rnix::SyntaxKind::TOKEN_UPDATE => "//", + rnix::SyntaxKind::TOKEN_ADD => "+", + rnix::SyntaxKind::TOKEN_SUB => "-", + rnix::SyntaxKind::TOKEN_MUL => "*", + rnix::SyntaxKind::TOKEN_DIV => "/", + rnix::SyntaxKind::TOKEN_AND_AND => "&&", + rnix::SyntaxKind::TOKEN_EQUAL => "==", + rnix::SyntaxKind::TOKEN_IMPLICATION => "->", + rnix::SyntaxKind::TOKEN_LESS => "<", + rnix::SyntaxKind::TOKEN_LESS_OR_EQ => "<=", + rnix::SyntaxKind::TOKEN_MORE => ">", + rnix::SyntaxKind::TOKEN_MORE_OR_EQ => ">=", + rnix::SyntaxKind::TOKEN_NOT_EQUAL => "!=", + rnix::SyntaxKind::TOKEN_OR_OR => "||", + rnix::SyntaxKind::TOKEN_FLOAT => "a float", + rnix::SyntaxKind::TOKEN_IDENT => "an identifier", + rnix::SyntaxKind::TOKEN_INTEGER => "an integer", + rnix::SyntaxKind::TOKEN_INTERPOL_END => "}", + rnix::SyntaxKind::TOKEN_INTERPOL_START => "${", + rnix::SyntaxKind::TOKEN_PATH => "a path", + rnix::SyntaxKind::TOKEN_URI => "a literal URI", + rnix::SyntaxKind::TOKEN_STRING_CONTENT => "content of a string", + rnix::SyntaxKind::TOKEN_STRING_END => "\"", + rnix::SyntaxKind::TOKEN_STRING_START => "\"", + + rnix::SyntaxKind::NODE_APPLY => "a function application", + rnix::SyntaxKind::NODE_ASSERT => "an assertion", + rnix::SyntaxKind::NODE_ATTRPATH => "an attribute path", + rnix::SyntaxKind::NODE_DYNAMIC => "a dynamic identifier", + + rnix::SyntaxKind::NODE_IDENT => "an identifier", + rnix::SyntaxKind::NODE_IF_ELSE => "an `if`-expression", + rnix::SyntaxKind::NODE_SELECT => "a `select`-expression", + rnix::SyntaxKind::NODE_INHERIT => "inherited values", + rnix::SyntaxKind::NODE_INHERIT_FROM => "inherited values", + rnix::SyntaxKind::NODE_STRING => "a string", + rnix::SyntaxKind::NODE_INTERPOL => "an interpolation", + rnix::SyntaxKind::NODE_LAMBDA => "a function", + rnix::SyntaxKind::NODE_IDENT_PARAM => "a function parameter", + rnix::SyntaxKind::NODE_LEGACY_LET => "a legacy `let`-expression", + rnix::SyntaxKind::NODE_LET_IN => "a `let`-expression", + rnix::SyntaxKind::NODE_LIST => "a list", + rnix::SyntaxKind::NODE_BIN_OP => "a binary operator", + rnix::SyntaxKind::NODE_PAREN => "a parenthesised expression", + rnix::SyntaxKind::NODE_PATTERN => "a function argument pattern", + rnix::SyntaxKind::NODE_PAT_BIND => "an argument pattern binding", + rnix::SyntaxKind::NODE_PAT_ENTRY => "an argument pattern entry", + rnix::SyntaxKind::NODE_ROOT => "a Nix expression", + rnix::SyntaxKind::NODE_ATTR_SET => "an attribute set", + rnix::SyntaxKind::NODE_ATTRPATH_VALUE => "an attribute set entry", + rnix::SyntaxKind::NODE_UNARY_OP => "a unary operator", + rnix::SyntaxKind::NODE_LITERAL => "a literal value", + rnix::SyntaxKind::NODE_WITH => "a `with`-expression", + rnix::SyntaxKind::NODE_PATH => "a path", + rnix::SyntaxKind::NODE_HAS_ATTR => "`?`-operator", + + // TODO(tazjin): unsure what these variants are, lets crash! + rnix::SyntaxKind::NODE_ERROR => todo!("NODE_ERROR found, tell tazjin!"), + rnix::SyntaxKind::TOKEN_ERROR => todo!("TOKEN_ERROR found, tell tazjin!"), + _ => todo!(), + } +} + +/// Construct the string representation for a list of expected parser tokens. +fn expected_syntax(one_of: &[rnix::SyntaxKind]) -> String { + match one_of.len() { + 0 => "nothing".into(), + 1 => format!("'{}'", name_for_syntax(&one_of[0])), + _ => { + let mut out: String = "one of: ".into(); + let end = one_of.len() - 1; + + for (idx, item) in one_of.iter().enumerate() { + if idx != 0 { + out.push_str(", "); + } else if idx == end { + out.push_str(", or "); + }; + + out.push_str(name_for_syntax(item)); + } + + out + } + } +} + +/// Process a list of parse errors into a set of span labels, annotating parse +/// errors. +fn spans_for_parse_errors(file: &File, errors: &[rnix::parser::ParseError]) -> Vec<SpanLabel> { + // rnix has a tendency to emit some identical errors more than once, but + // they do not enhance the user experience necessarily, so we filter them + // out + let mut had_eof = false; + + errors + .iter() + .enumerate() + .filter_map(|(idx, err)| { + let (span, label): (Span, String) = match err { + rnix::parser::ParseError::Unexpected(range) => ( + range.span_for(file), + "found an unexpected syntax element here".into(), + ), + + rnix::parser::ParseError::UnexpectedExtra(range) => ( + range.span_for(file), + "found unexpected extra elements at the root of the expression".into(), + ), + + rnix::parser::ParseError::UnexpectedWanted(found, range, wanted) => { + let span = range.span_for(file); + ( + span, + format!( + "found '{}', but expected {}", + name_for_syntax(found), + expected_syntax(wanted), + ), + ) + } + + rnix::parser::ParseError::UnexpectedEOF => { + if had_eof { + return None; + } + + had_eof = true; + + ( + file.span, + "code ended unexpectedly while the parser still expected more".into(), + ) + } + + rnix::parser::ParseError::UnexpectedEOFWanted(wanted) => { + had_eof = true; + + ( + file.span, + format!( + "code ended unexpectedly, but wanted {}", + expected_syntax(wanted) + ), + ) + } + + rnix::parser::ParseError::DuplicatedArgs(range, name) => ( + range.span_for(file), + format!( + "the function argument pattern '{}' was bound more than once", + name + ), + ), + + rnix::parser::ParseError::RecursionLimitExceeded => ( + file.span, + "this code exceeds the parser's recursion limit, please report a Tvix bug" + .to_string(), + ), + + // TODO: can rnix even still throw this? it's semantic! + rnix::parser::ParseError::UnexpectedDoubleBind(range) => ( + range.span_for(file), + "this pattern was bound more than once".into(), + ), + + // The error enum is marked as `#[non_exhaustive]` in rnix, + // which disables the compiler error for missing a variant. This + // feature makes it possible for users to miss critical updates + // of enum variants for a more exciting runtime experience. + new => todo!("new parse error variant: {}", new), + }; + + Some(SpanLabel { + span, + label: Some(label), + style: if idx == 0 { + SpanStyle::Primary + } else { + SpanStyle::Secondary + }, + }) + }) + .collect() +} + +impl Error { + pub fn fancy_format_str(&self, source: &SourceCode) -> String { + let mut out = vec![]; + Emitter::vec(&mut out, Some(&*source.codemap())).emit(&self.diagnostics(source)); + String::from_utf8_lossy(&out).to_string() + } + + /// Render a fancy, human-readable output of this error and print + /// it to stderr. + pub fn fancy_format_stderr(&self, source: &SourceCode) { + Emitter::stderr(ColorConfig::Auto, Some(&*source.codemap())) + .emit(&self.diagnostics(source)); + } + + /// Create the optional span label displayed as an annotation on + /// the underlined span of the error. + fn span_label(&self) -> Option<String> { + let label = match &self.kind { + ErrorKind::DuplicateAttrsKey { .. } => "in this attribute set", + ErrorKind::InvalidAttributeName(_) => "in this attribute set", + ErrorKind::RelativePathResolution(_) => "in this path literal", + ErrorKind::UnexpectedArgument { .. } => "in this function call", + + // The spans for some errors don't have any more descriptive stuff + // in them, or we don't utilise it yet. + ErrorKind::Abort(_) + | ErrorKind::AttributeNotFound { .. } + | ErrorKind::IndexOutOfBounds { .. } + | ErrorKind::TailEmptyList + | ErrorKind::TypeError { .. } + | ErrorKind::Incomparable { .. } + | ErrorKind::DivisionByZero + | ErrorKind::DynamicKeyInScope(_) + | ErrorKind::UnknownStaticVariable + | ErrorKind::UnknownDynamicVariable(_) + | ErrorKind::VariableAlreadyDefined(_) + | ErrorKind::NotCallable(_) + | ErrorKind::InfiniteRecursion { .. } + | ErrorKind::ParseErrors(_) + | ErrorKind::NativeError { .. } + | ErrorKind::BytecodeError(_) + | ErrorKind::NotCoercibleToString { .. } + | ErrorKind::NotAnAbsolutePath(_) + | ErrorKind::ParseIntError(_) + | ErrorKind::UnmergeableInherit { .. } + | ErrorKind::UnmergeableValue + | ErrorKind::ImportParseError { .. } + | ErrorKind::ImportCompilerError { .. } + | ErrorKind::IO { .. } + | ErrorKind::FromJsonError(_) + | ErrorKind::NotSerialisableToJson(_) + | ErrorKind::FromTomlError(_) + | ErrorKind::Xml(_) + | ErrorKind::TvixError(_) + | ErrorKind::TvixBug { .. } + | ErrorKind::NotImplemented(_) + | ErrorKind::WithContext { .. } => return None, + }; + + Some(label.into()) + } + + /// Return the unique error code for this variant which can be + /// used to refer users to documentation. + fn code(&self) -> &'static str { + match self.kind { + ErrorKind::Abort(_) => "E002", + ErrorKind::InvalidAttributeName { .. } => "E004", + ErrorKind::AttributeNotFound { .. } => "E005", + ErrorKind::TypeError { .. } => "E006", + ErrorKind::Incomparable { .. } => "E007", + ErrorKind::DynamicKeyInScope(_) => "E009", + ErrorKind::UnknownStaticVariable => "E010", + ErrorKind::UnknownDynamicVariable(_) => "E011", + ErrorKind::VariableAlreadyDefined(_) => "E012", + ErrorKind::NotCallable(_) => "E013", + ErrorKind::InfiniteRecursion { .. } => "E014", + ErrorKind::ParseErrors(_) => "E015", + ErrorKind::DuplicateAttrsKey { .. } => "E016", + ErrorKind::NotCoercibleToString { .. } => "E018", + ErrorKind::IndexOutOfBounds { .. } => "E019", + ErrorKind::NotAnAbsolutePath(_) => "E020", + ErrorKind::ParseIntError(_) => "E021", + ErrorKind::TailEmptyList { .. } => "E023", + ErrorKind::UnmergeableInherit { .. } => "E024", + ErrorKind::UnmergeableValue => "E025", + ErrorKind::ImportParseError { .. } => "E027", + ErrorKind::ImportCompilerError { .. } => "E028", + ErrorKind::IO { .. } => "E029", + ErrorKind::FromJsonError { .. } => "E030", + ErrorKind::UnexpectedArgument { .. } => "E031", + ErrorKind::RelativePathResolution(_) => "E032", + ErrorKind::DivisionByZero => "E033", + ErrorKind::Xml(_) => "E034", + ErrorKind::FromTomlError(_) => "E035", + ErrorKind::NotSerialisableToJson(_) => "E036", + + // Special error code for errors from other Tvix + // components. We may want to introduce a code namespacing + // system to have these errors pass codes through. + ErrorKind::TvixError(_) => "E997", + + // Special error code that is not part of the normal + // ordering. + ErrorKind::TvixBug { .. } => "E998", + + // Placeholder error while Tvix is under construction. + ErrorKind::NotImplemented(_) => "E999", + + // Chained errors should yield the code of the innermost + // error. + ErrorKind::NativeError { ref err, .. } | ErrorKind::BytecodeError(ref err) => { + err.code() + } + + ErrorKind::WithContext { .. } => { + panic!("internal ErrorKind::WithContext variant leaked") + } + } + } + + fn spans(&self, source: &SourceCode) -> Vec<SpanLabel> { + let mut spans = match &self.kind { + ErrorKind::ImportParseError { errors, file, .. } => { + spans_for_parse_errors(file, errors) + } + + ErrorKind::ParseErrors(errors) => { + let file = source.get_file(self.span); + spans_for_parse_errors(&file, errors) + } + + ErrorKind::UnexpectedArgument { formals_span, .. } => { + vec![ + SpanLabel { + label: self.span_label(), + span: self.span, + style: SpanStyle::Primary, + }, + SpanLabel { + label: Some("the accepted arguments".into()), + span: *formals_span, + style: SpanStyle::Secondary, + }, + ] + } + + ErrorKind::InfiniteRecursion { + first_force, + suspended_at, + content_span, + } => { + let mut spans = vec![]; + + if let Some(content_span) = content_span { + spans.push(SpanLabel { + label: Some("this lazily-evaluated code".into()), + span: *content_span, + style: SpanStyle::Secondary, + }) + } + + if let Some(suspended_at) = suspended_at { + spans.push(SpanLabel { + label: Some("which was instantiated here".into()), + span: *suspended_at, + style: SpanStyle::Secondary, + }) + } + + spans.push(SpanLabel { + label: Some("was first requested to be evaluated here".into()), + span: *first_force, + style: SpanStyle::Secondary, + }); + + spans.push(SpanLabel { + label: Some("but then requested again here during its own evaluation".into()), + span: self.span, + style: SpanStyle::Primary, + }); + + spans + } + + // All other errors pretty much have the same shape. + _ => { + vec![SpanLabel { + label: self.span_label(), + span: self.span, + style: SpanStyle::Primary, + }] + } + }; + + for ctx in &self.contexts { + spans.push(SpanLabel { + label: Some(format!("while {}", ctx)), + span: self.span, + style: SpanStyle::Secondary, + }); + } + + spans + } + + /// Create the primary diagnostic for a given error. + fn diagnostic(&self, source: &SourceCode) -> Diagnostic { + Diagnostic { + level: Level::Error, + message: self.to_string(), + spans: self.spans(source), + code: Some(self.code().into()), + } + } + + /// Return the primary diagnostic and all further associated diagnostics (if + /// any) of an error. + fn diagnostics(&self, source: &SourceCode) -> Vec<Diagnostic> { + match &self.kind { + ErrorKind::ImportCompilerError { errors, .. } => { + let mut out = vec![self.diagnostic(source)]; + out.extend(errors.iter().map(|e| e.diagnostic(source))); + out + } + + // When encountering either of these error kinds, we are dealing + // with the top of an error chain. + // + // An error chain creates a list of diagnostics which provide trace + // information. + // + // We don't know how deep this chain is, so we avoid recursing in + // this function while unrolling the chain. + ErrorKind::NativeError { err: next, .. } | ErrorKind::BytecodeError(next) => { + // Accumulated diagnostics to return. + let mut diagnostics: Vec<Diagnostic> = vec![]; + + // The next (inner) error to add to the diagnostics, after this + // one. + let mut next = *next.clone(); + + // Diagnostic message for *this* error. + let mut this_message = self.to_string(); + + // Primary span for *this* error. + let mut this_span = self.span; + + // Diagnostic spans for *this* error. + let mut this_spans = self.spans(source); + + loop { + if is_new_span( + this_span, + diagnostics.last().and_then(|last| last.spans.last()), + ) { + diagnostics.push(Diagnostic { + level: Level::Note, + message: this_message, + spans: this_spans, + code: None, // only the top-level error has one + }); + } + + this_message = next.to_string(); + this_span = next.span; + this_spans = next.spans(source); + + match next.kind { + ErrorKind::NativeError { err: inner, .. } + | ErrorKind::BytecodeError(inner) => { + next = *inner; + continue; + } + _ => { + diagnostics.extend(next.diagnostics(source)); + break; + } + } + } + + diagnostics + } + + _ => vec![self.diagnostic(source)], + } + } +} + +// Check if this error is in a different span from its immediate ancestor. +fn is_new_span(this_span: Span, parent: Option<&SpanLabel>) -> bool { + match parent { + None => true, + Some(parent) => parent.span != this_span, + } +} + +// Convenience methods to add context on other types. +pub trait AddContext { + /// Add context to the error-carrying type. + fn context<S: Into<String>>(self, ctx: S) -> Self; +} + +impl AddContext for ErrorKind { + fn context<S: Into<String>>(self, ctx: S) -> Self { + ErrorKind::WithContext { + context: ctx.into(), + underlying: Box::new(self), + } + } +} + +impl<T> AddContext for Result<T, ErrorKind> { + fn context<S: Into<String>>(self, ctx: S) -> Self { + self.map_err(|kind| kind.context(ctx)) + } +} + +impl<T> AddContext for Result<T, Error> { + fn context<S: Into<String>>(self, ctx: S) -> Self { + self.map_err(|err| Error { + kind: err.kind.context(ctx), + ..err + }) + } +} |