feat(tvix/eval): implement initial fancy display for warnings

This implements an initial fancy display for warnings emitted by the
tvix compiler, using the codemap_diagnostic crate.

Each warning variant has an associated message, and optionally an
associated annotation for the span displayed to the user.

In theory we could get a lot more fancy with the display for specific
variants if needed (e.g. re-parse the AST and actually add multiple
semantic spans based on context), but this is already a good start.

Example:

  tvix-repl> let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
  warning[W004]: declared variable 'toString' shadows a built-in global!
   --> [tvix-repl]:1:5
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |     ^^^^^^^^ variable declared here

  warning[W001]: URL literal syntax is deprecated, use a quoted string instead
   --> [tvix-repl]:1:16
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |                ^^^^^^^^^^^^^^^

  warning[W002]: inherited variable already exists with the same value
   --> [tvix-repl]:1:40
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |                                        ^^^^^^^^^^^^^^^^^

  warning[W999]: feature not yet implemented in tvix: recursive attribute sets
   --> [tvix-repl]:1:70
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |                                                                      ^^^^^^

  warning[W999]: feature not yet implemented in tvix: closed formals
   --> [tvix-repl]:1:62
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |                                                              ^^

  warning[W003]: variable 'toString' is declared, but never used:
   --> [tvix-repl]:1:5
    |
  1 | let toString = https://tvl.fyi; in let inherit toString; in ({}: 42) rec {}
    |     ^^^^^^^^ variable declared here

  => 42 :: int

These are coloured when output to a terminal.

Change-Id: If315648a07e333895db4ae1d0915ee2013806585
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6532
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2022-09-12 01:44:17 +03:00 committed by tazjin
parent beb78c7104
commit 4f67cf221a
3 changed files with 94 additions and 9 deletions

View file

@ -33,7 +33,7 @@ impl Compiler<'_, '_> {
let span = self.span_for(&node);
self.emit_warning(
span,
WarningKind::NotImplemented("recursive attribute sets are not yet implemented"),
WarningKind::NotImplemented("recursive attribute sets"),
);
}

View file

@ -13,7 +13,7 @@ pub fn interpret(code: &str, location: Option<PathBuf>) -> EvalResult<Value> {
location
.as_ref()
.map(|p| p.to_string_lossy().to_string())
.unwrap_or_else(|| "<repl>".into()),
.unwrap_or_else(|| "[tvix-repl]".into()),
code.into(),
);
let codemap = Rc::new(codemap);
@ -47,7 +47,7 @@ pub fn interpret(code: &str, location: Option<PathBuf>) -> EvalResult<Value> {
location,
&file,
global_builtins(),
&mut DisassemblingObserver::new(codemap, std::io::stderr()),
&mut DisassemblingObserver::new(codemap.clone(), std::io::stderr()),
)
} else {
crate::compiler::compile(
@ -60,12 +60,7 @@ pub fn interpret(code: &str, location: Option<PathBuf>) -> EvalResult<Value> {
}?;
for warning in result.warnings {
eprintln!(
"warning: {:?} at `{}`[line {}]",
warning.kind,
file.source_slice(warning.span),
file.find_line(warning.span.low()) + 1
)
warning.fancy_format_stderr(&codemap);
}
for error in &result.errors {

View file

@ -1,6 +1,9 @@
//! Implements warnings that are emitted in cases where code passed to
//! Tvix exhibits problems that the user could address.
use codemap::CodeMap;
use codemap_diagnostic::{ColorConfig, Diagnostic, Emitter, Level, SpanLabel, SpanStyle};
#[derive(Debug)]
pub enum WarningKind {
DeprecatedLiteralURL,
@ -18,3 +21,90 @@ pub struct EvalWarning {
pub kind: WarningKind,
pub span: codemap::Span,
}
impl EvalWarning {
/// Render a fancy, human-readable output of this warning and
/// return it as a String. Note that this version of the output
/// does not include any colours or font styles.
pub fn fancy_format_str(&self, codemap: &CodeMap) -> String {
let mut out = vec![];
Emitter::vec(&mut out, Some(codemap)).emit(&[self.diagnostic(codemap)]);
String::from_utf8_lossy(&out).to_string()
}
/// Render a fancy, human-readable output of this warning and
/// print it to stderr. If rendered in a terminal that supports
/// colours and font styles, the output will include those.
pub fn fancy_format_stderr(&self, codemap: &CodeMap) {
Emitter::stderr(ColorConfig::Auto, Some(codemap)).emit(&[self.diagnostic(codemap)]);
}
/// Create the optional span label displayed as an annotation on
/// the underlined span of the warning.
fn span_label(&self) -> Option<String> {
match self.kind {
WarningKind::UnusedBinding | WarningKind::ShadowedGlobal(_) => {
Some("variable declared here".into())
}
_ => None,
}
}
/// Create the primary warning message displayed to users for a
/// warning.
fn message(&self, codemap: &CodeMap) -> String {
match self.kind {
WarningKind::DeprecatedLiteralURL => {
format!("URL literal syntax is deprecated, use a quoted string instead")
}
WarningKind::UselessInherit => {
format!("inherited variable already exists with the same value")
}
WarningKind::UnusedBinding => {
let file = codemap.find_file(self.span.low());
format!(
"variable '{}' is declared, but never used:",
file.source_slice(self.span)
)
}
WarningKind::ShadowedGlobal(name) => {
format!("declared variable '{}' shadows a built-in global!", name)
}
WarningKind::NotImplemented(what) => {
format!("feature not yet implemented in tvix: {}", what)
}
}
}
/// Return the unique warning code for this variant which can be
/// used to refer users to documentation.
fn code(&self) -> &'static str {
match self.kind {
WarningKind::DeprecatedLiteralURL => "W001",
WarningKind::UselessInherit => "W002",
WarningKind::UnusedBinding => "W003",
WarningKind::ShadowedGlobal(_) => "W004",
WarningKind::NotImplemented(_) => "W999",
}
}
fn diagnostic(&self, codemap: &CodeMap) -> Diagnostic {
let span_label = SpanLabel {
label: self.span_label(),
span: self.span,
style: SpanStyle::Primary,
};
Diagnostic {
level: Level::Warning,
message: self.message(codemap),
spans: vec![span_label],
code: Some(self.code().into()),
}
}
}