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-rw-r--r--dhall/src/error/builder.rs100
-rw-r--r--dhall/src/error/mod.rs3
-rw-r--r--dhall/src/semantics/nze/value.rs4
-rw-r--r--dhall/src/semantics/tck/typecheck.rs54
-rw-r--r--dhall/src/syntax/ast/span.rs30
5 files changed, 169 insertions, 22 deletions
diff --git a/dhall/src/error/builder.rs b/dhall/src/error/builder.rs
new file mode 100644
index 0000000..e293220
--- /dev/null
+++ b/dhall/src/error/builder.rs
@@ -0,0 +1,100 @@
+use annotate_snippets::{
+ display_list::DisplayList,
+ formatter::DisplayListFormatter,
+ snippet::{Annotation, AnnotationType, Slice, Snippet, SourceAnnotation},
+};
+
+use crate::syntax::Span;
+
+#[derive(Debug, Clone)]
+pub struct ErrorBuilder {
+ message: String,
+ annotation_type: AnnotationType,
+ annotations: Vec<BuilderAnnotation>,
+}
+
+#[derive(Debug, Clone)]
+struct BuilderAnnotation {
+ span: Span,
+ message: String,
+ annotation_type: AnnotationType,
+}
+
+/// A builder that uses the annotate_snippets library to display nice error messages about source
+/// code locations.
+impl ErrorBuilder {
+ pub fn new(message: String) -> Self {
+ ErrorBuilder {
+ message,
+ annotation_type: AnnotationType::Error,
+ annotations: Vec::new(),
+ }
+ }
+ pub fn span_err(span: &Span, message: String) -> Self {
+ let mut builder = Self::new(message.clone());
+ builder.annotate_err(span, message);
+ builder
+ }
+
+ pub fn annotate_err(&mut self, span: &Span, message: String) {
+ self.annotations.push(BuilderAnnotation {
+ span: span.clone(),
+ message,
+ annotation_type: AnnotationType::Error,
+ })
+ }
+ pub fn annotate_info(&mut self, span: &Span, message: String) {
+ self.annotations.push(BuilderAnnotation {
+ span: span.clone(),
+ message,
+ annotation_type: AnnotationType::Help,
+ })
+ }
+
+ // TODO: handle multiple files
+ pub fn format(self) -> String {
+ let mut input = None;
+ let annotations = self
+ .annotations
+ .into_iter()
+ .filter_map(|annot| {
+ let span = match annot.span {
+ Span::Parsed(span) => span,
+ _ => return None,
+ };
+ if input.is_none() {
+ input = Some(span.to_input());
+ }
+ Some(SourceAnnotation {
+ label: annot.message,
+ annotation_type: annot.annotation_type,
+ range: span.as_char_range(),
+ })
+ })
+ .collect();
+
+ let input = match input {
+ Some(input) => input,
+ None => return format!("[unknown location] {}", self.message),
+ };
+
+ let snippet = Snippet {
+ title: Some(Annotation {
+ label: Some(self.message),
+ id: None,
+ annotation_type: self.annotation_type,
+ }),
+ footer: vec![],
+ slices: vec![Slice {
+ source: input,
+ line_start: 1, // TODO
+ origin: Some("<current file>".to_string()),
+ fold: true,
+ annotations,
+ }],
+ };
+ let dl = DisplayList::from(snippet);
+ let dlf = DisplayListFormatter::new(true, false);
+ format!("{}", dlf.format(&dl))
+ }
+}
diff --git a/dhall/src/error/mod.rs b/dhall/src/error/mod.rs
index 4df018d..5b7693e 100644
--- a/dhall/src/error/mod.rs
+++ b/dhall/src/error/mod.rs
@@ -5,6 +5,9 @@ use crate::semantics::Value;
use crate::syntax::{Import, ParseError};
use crate::NormalizedExpr;
+mod builder;
+pub(crate) use builder::*;
+
pub type Result<T> = std::result::Result<T, Error>;
#[derive(Debug)]
diff --git a/dhall/src/semantics/nze/value.rs b/dhall/src/semantics/nze/value.rs
index ae06942..d97b8c4 100644
--- a/dhall/src/semantics/nze/value.rs
+++ b/dhall/src/semantics/nze/value.rs
@@ -6,6 +6,7 @@ use crate::semantics::nze::lazy;
use crate::semantics::Binder;
use crate::semantics::{
apply_any, normalize_one_layer, normalize_tyexpr_whnf, squash_textlit,
+ TyEnv,
};
use crate::semantics::{type_of_builtin, typecheck, TyExpr, TyExprKind};
use crate::semantics::{BuiltinClosure, NzEnv, NzVar, VarEnv};
@@ -192,6 +193,9 @@ impl Value {
self.to_tyexpr_noenv().to_expr(opts)
}
+ pub(crate) fn to_expr_tyenv(&self, env: &TyEnv) -> NormalizedExpr {
+ self.to_tyexpr(env.as_varenv()).to_expr_tyenv(env)
+ }
pub(crate) fn to_whnf_ignore_type(&self) -> ValueKind {
self.kind().clone()
}
diff --git a/dhall/src/semantics/tck/typecheck.rs b/dhall/src/semantics/tck/typecheck.rs
index 20076cd..a652663 100644
--- a/dhall/src/semantics/tck/typecheck.rs
+++ b/dhall/src/semantics/tck/typecheck.rs
@@ -2,7 +2,7 @@ use std::borrow::Cow;
use std::cmp::max;
use std::collections::HashMap;
-use crate::error::{TypeError, TypeMessage};
+use crate::error::{ErrorBuilder, TypeError, TypeMessage};
use crate::semantics::merge_maps;
use crate::semantics::{
type_of_builtin, Binder, BuiltinClosure, Closure, TyEnv, TyExpr,
@@ -57,6 +57,7 @@ fn mkerr<T, S: ToString>(x: S) -> Result<T, TypeError> {
fn type_one_layer(
env: &TyEnv,
kind: &ExprKind<TyExpr, Normalized>,
+ span: Span,
) -> Result<Type, TypeError> {
Ok(match kind {
ExprKind::Import(..) => unreachable!(
@@ -252,27 +253,35 @@ fn type_one_layer(
}
t
}
- ExprKind::App(f, arg) => {
- match f.get_type()?.kind() {
- ValueKind::PiClosure { annot, closure, .. } => {
- if arg.get_type()? != *annot {
- // return mkerr(format!("function annot mismatch"));
- return mkerr(format!(
- "function annot mismatch: ({} : {}) : {}",
- arg.to_expr_tyenv(env),
- arg.get_type()?
- .to_tyexpr(env.as_varenv())
- .to_expr_tyenv(env),
- annot.to_tyexpr(env.as_varenv()).to_expr_tyenv(env),
- ));
- }
-
- let arg_nf = arg.eval(env.as_nzenv());
- closure.apply(arg_nf)
+ ExprKind::App(f, arg) => match f.get_type()?.kind() {
+ ValueKind::PiClosure { annot, closure, .. } => {
+ if arg.get_type()? != *annot {
+ let mut builder = ErrorBuilder::span_err(
+ &span,
+ format!("function annot mismatch",),
+ );
+ builder.annotate_info(
+ &f.span(),
+ format!(
+ "this expects an argument of type: {}",
+ annot.to_expr_tyenv(env),
+ ),
+ );
+ builder.annotate_info(
+ &arg.span(),
+ format!(
+ "but this has type: {}",
+ arg.get_type()?.to_expr_tyenv(env),
+ ),
+ );
+ return mkerr(builder.format());
}
- _ => return mkerr(format!("apply to not Pi")),
+
+ let arg_nf = arg.eval(env.as_nzenv());
+ closure.apply(arg_nf)
}
- }
+ _ => return mkerr(format!("apply to not Pi")),
+ },
ExprKind::BoolIf(x, y, z) => {
if *x.get_type()?.kind() != ValueKind::from_builtin(Builtin::Bool) {
return mkerr("InvalidPredicate");
@@ -323,7 +332,7 @@ fn type_one_layer(
x.get_type()?.to_tyexpr(env.as_varenv()),
y.get_type()?.to_tyexpr(env.as_varenv()),
);
- let ty = type_one_layer(env, &ekind)?;
+ let ty = type_one_layer(env, &ekind, Span::Artificial)?;
TyExpr::new(TyExprKind::Expr(ekind), Some(ty), Span::Artificial)
.eval(env.as_nzenv())
}
@@ -347,6 +356,7 @@ fn type_one_layer(
tx.to_tyexpr(env.as_varenv()),
ty.to_tyexpr(env.as_varenv()),
),
+ Span::Artificial,
)?;
}
}
@@ -588,7 +598,7 @@ pub(crate) fn type_with(
}
ekind => {
let ekind = ekind.traverse_ref(|e| type_with(env, e))?;
- let ty = type_one_layer(env, &ekind)?;
+ let ty = type_one_layer(env, &ekind, expr.span())?;
(TyExprKind::Expr(ekind), Some(ty))
}
};
diff --git a/dhall/src/syntax/ast/span.rs b/dhall/src/syntax/ast/span.rs
index f9c7008..ffdd82c 100644
--- a/dhall/src/syntax/ast/span.rs
+++ b/dhall/src/syntax/ast/span.rs
@@ -24,6 +24,20 @@ pub enum Span {
Artificial,
}
+impl ParsedSpan {
+ pub(crate) fn to_input(&self) -> String {
+ self.input.to_string()
+ }
+ /// Convert to a char range for consumption by annotate_snippets.
+ /// This compensates for https://github.com/rust-lang/annotate-snippets-rs/issues/24
+ pub(crate) fn as_char_range(&self) -> (usize, usize) {
+ (
+ char_idx_from_byte_idx(&self.input, self.start),
+ char_idx_from_byte_idx(&self.input, self.end),
+ )
+ }
+}
+
impl Span {
pub(crate) fn make(input: Rc<str>, sp: pest::Span) -> Self {
Span::Parsed(ParsedSpan {
@@ -79,3 +93,19 @@ impl Span {
format!("{}", err)
}
}
+
+/// Convert a byte idx into a string into a char idx for consumption by annotate_snippets.
+fn char_idx_from_byte_idx(input: &str, idx: usize) -> usize {
+ let char_idx = input
+ .char_indices()
+ .enumerate()
+ .find(|(_, (i, _))| *i == idx)
+ .unwrap()
+ .0;
+ // Unix-style newlines are counted as two chars (see
+ // https://github.com/rust-lang/annotate-snippets-rs/issues/24).
+ let nbr_newlines = input[..idx].chars().filter(|c| *c == '\n').count();
+ let nbr_carriage_returns =
+ input[..idx].chars().filter(|c| *c == '\r').count();
+ char_idx + nbr_newlines - nbr_carriage_returns
+}