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[draft] multiple single-line suggestions on malformed function calls when possible #145630

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[draft] multiple single-line suggestions on malformed function calls when possible #145630

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204 changes: 136 additions & 68 deletions compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1179,10 +1179,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let mut only_extras_so_far = errors
.peek()
.is_some_and(|first| matches!(first, Error::Extra(arg_idx) if arg_idx.index() == 0));
let mut only_missing_so_far = true;
let mut prev_extra_idx = None;
let mut suggestions = vec![];
while let Some(error) = errors.next() {
only_extras_so_far &= matches!(error, Error::Extra(_));
only_missing_so_far &= matches!(error, Error::Missing(_));

match error {
Error::Invalid(provided_idx, expected_idx, compatibility) => {
Expand Down Expand Up @@ -1580,80 +1582,146 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
&& !full_call_span.in_external_macro(self.sess().source_map())
{
let source_map = self.sess().source_map();
let suggestion_span = if let Some(args_span) = error_span.trim_start(full_call_span) {
// Span of the braces, e.g. `(a, b, c)`.
args_span
} else {
// The arg span of a function call that wasn't even given braces
// like what might happen with delegation reuse.
// e.g. `reuse HasSelf::method;` should suggest `reuse HasSelf::method($args);`.
full_call_span.shrink_to_hi()
};

// Controls how the arguments should be listed in the suggestion.
enum ArgumentsFormatting {
SingleLine,
Multiline { fallback_indent: String, brace_indent: String },
}
let arguments_formatting = {
let mut provided_inputs = matched_inputs.iter().filter_map(|a| *a);
if let Some(brace_indent) = source_map.indentation_before(suggestion_span)
&& let Some(first_idx) = provided_inputs.by_ref().next()
&& let Some(last_idx) = provided_inputs.by_ref().next()
&& let (_, first_span) = provided_arg_tys[first_idx]
&& let (_, last_span) = provided_arg_tys[last_idx]
&& source_map.is_multiline(first_span.to(last_span))
&& let Some(fallback_indent) = source_map.indentation_before(first_span)
{
ArgumentsFormatting::Multiline { fallback_indent, brace_indent }
let (suggestion_span, has_paren) =
if let Some(args_span) = error_span.trim_start(full_call_span) {
// Span of the braces, e.g. `(a, b, c)`.
(args_span, true)
} else {
ArgumentsFormatting::SingleLine
}
};
// The arg span of a function call that wasn't even given braces
// like what might happen with delegation reuse.
// e.g. `reuse HasSelf::method;` should suggest `reuse HasSelf::method($args);`.
(full_call_span.shrink_to_hi(), false)
};

let mut suggestion = "(".to_owned();
let mut needs_comma = false;
for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() {
if needs_comma {
suggestion += ",";
}
match &arguments_formatting {
ArgumentsFormatting::SingleLine if needs_comma => suggestion += " ",
ArgumentsFormatting::SingleLine => {}
ArgumentsFormatting::Multiline { .. } => suggestion += "\n",
if has_paren && only_missing_so_far {
// Controls how the arguments should be listed in the suggestion.
enum ArgumentsFormatting {
SingleLine,
Multiline { fallback_indent: String },
}
needs_comma = true;
let (suggestion_span, suggestion_text) = if let Some(provided_idx) = provided_idx
&& let (_, provided_span) = provided_arg_tys[*provided_idx]
&& let Ok(arg_text) = source_map.span_to_snippet(provided_span)
{
(Some(provided_span), arg_text)
} else {
// Propose a placeholder of the correct type
let (_, expected_ty) = formal_and_expected_inputs[expected_idx];
(None, ty_to_snippet(expected_ty, expected_idx))
let arguments_formatting = {
let mut provided_inputs = matched_inputs.iter().filter_map(|a| *a);
if let Some(first_idx) = provided_inputs.by_ref().next()
&& let Some(last_idx) = provided_inputs.by_ref().next()
&& let (_, first_span) = provided_arg_tys[first_idx]
&& let (_, last_span) = provided_arg_tys[last_idx]
&& source_map.is_multiline(first_span.to(last_span))
&& let Some(fallback_indent) = source_map.indentation_before(first_span)
{
ArgumentsFormatting::Multiline { fallback_indent }
} else {
ArgumentsFormatting::SingleLine
}
};
if let ArgumentsFormatting::Multiline { fallback_indent, .. } =
&arguments_formatting
{
let indent = suggestion_span
.and_then(|span| source_map.indentation_before(span))
.unwrap_or_else(|| fallback_indent.clone());
suggestion += &indent;

let mut suggestions: Vec<(Span, String)> = Vec::new();
let mut previous_span = source_map.start_point(suggestion_span).shrink_to_hi();
let mut no_provided_arg_yet = true;
for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() {
if let Some(provided_idx) = provided_idx {
let (_, provided_span) = provided_arg_tys[*provided_idx];
previous_span = provided_span;
no_provided_arg_yet = false;
} else {
// Propose a placeholder of the correct type
let (insertion_span, last_arg) = if no_provided_arg_yet {
(previous_span, matched_inputs.len() - 1 == expected_idx.as_usize())
} else {
let mut comma_hit = false;
let mut closing_paren_hit = false;
let after_arg = previous_span.shrink_to_hi();
let after_previous_comma = source_map
.span_extend_while(after_arg, |c| {
closing_paren_hit = c == ')';
if comma_hit || closing_paren_hit {
false
} else {
comma_hit = c == ',';
true
}
})
.unwrap()
.shrink_to_hi();
let span = if closing_paren_hit {
after_previous_comma
} else {
source_map.next_point(after_previous_comma).shrink_to_hi()
};
(span, closing_paren_hit)
};
let (_, expected_ty) = formal_and_expected_inputs[expected_idx];
let expected_ty = ty_to_snippet(expected_ty, expected_idx);
let indent = match arguments_formatting {
ArgumentsFormatting::SingleLine => "",
ArgumentsFormatting::Multiline { ref fallback_indent, .. } => {
fallback_indent
}
};
let prefix = if last_arg && !no_provided_arg_yet {
// `call(a)` -> `call(a, b)` requires adding a comma.
", "
} else {
""
};
let suffix = match arguments_formatting {
ArgumentsFormatting::SingleLine if !last_arg => ", ",
ArgumentsFormatting::SingleLine => "",
ArgumentsFormatting::Multiline { .. } => "\n",
};
let suggestion = format!("{indent}{prefix}{expected_ty}{suffix}");
if let Some((last_sugg_span, last_sugg_msg)) = suggestions.last_mut()
&& *last_sugg_span == insertion_span
{
// More than one suggestion to insert at a given span.
// Merge them into one.
if last_sugg_msg.ends_with(", ") && prefix == ", " {
// FIXME(scrabsha): explain what this condition is and why
// it is needed.
// FIXME(scrabsha): find a better way to express this
// condition.
last_sugg_msg.truncate(last_sugg_msg.len() - 2);
}
last_sugg_msg.push_str(&suggestion);
} else {
suggestions.push((insertion_span, suggestion));
};
};
}
suggestion += &suggestion_text;
}
if let ArgumentsFormatting::Multiline { brace_indent, .. } = arguments_formatting {
suggestion += ",\n";
suggestion += &brace_indent;
err.multipart_suggestion_verbose(
suggestion_text,
suggestions,
Applicability::HasPlaceholders,
);
} else {
// FIXME: make this multiline-aware.
let mut suggestion = "(".to_owned();
let mut needs_comma = false;
for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() {
if needs_comma {
suggestion += ", ";
} else {
needs_comma = true;
}
let suggestion_text = if let Some(provided_idx) = provided_idx
&& let (_, provided_span) = provided_arg_tys[*provided_idx]
&& let Ok(arg_text) = source_map.span_to_snippet(provided_span)
{
arg_text
} else {
// Propose a placeholder of the correct type
let (_, expected_ty) = formal_and_expected_inputs[expected_idx];
ty_to_snippet(expected_ty, expected_idx)
};
suggestion += &suggestion_text;
}
suggestion += ")";
err.span_suggestion_verbose(
suggestion_span,
suggestion_text,
suggestion,
Applicability::HasPlaceholders,
);
}
suggestion += ")";
err.span_suggestion_verbose(
suggestion_span,
suggestion_text,
suggestion,
Applicability::HasPlaceholders,
);
}

err.emit()
Expand Down
10 changes: 7 additions & 3 deletions compiler/rustc_span/src/source_map.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -543,9 +543,13 @@ impl SourceMap {
/// Extracts the source surrounding the given `Span` using the `extract_source` function. The
/// extract function takes three arguments: a string slice containing the source, an index in
/// the slice for the beginning of the span and an index in the slice for the end of the span.
pub fn span_to_source<F, T>(&self, sp: Span, extract_source: F) -> Result<T, SpanSnippetError>
pub fn span_to_source<F, T>(
&self,
sp: Span,
mut extract_source: F,
) -> Result<T, SpanSnippetError>
where
F: Fn(&str, usize, usize) -> Result<T, SpanSnippetError>,
F: FnMut(&str, usize, usize) -> Result<T, SpanSnippetError>,
{
let local_begin = self.lookup_byte_offset(sp.lo());
let local_end = self.lookup_byte_offset(sp.hi());
Expand Down Expand Up @@ -700,7 +704,7 @@ impl SourceMap {
pub fn span_extend_while(
&self,
span: Span,
f: impl Fn(char) -> bool,
mut f: impl FnMut(char) -> bool,
) -> Result<Span, SpanSnippetError> {
self.span_to_source(span, |s, _start, end| {
let n = s[end..].char_indices().find(|&(_, c)| !f(c)).map_or(s.len() - end, |(i, _)| i);
Expand Down
18 changes: 4 additions & 14 deletions tests/ui/argument-suggestions/issue-100478.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,8 @@ LL | fn three_diff(_a: T1, _b: T2, _c: T3) {}
| ^^^^^^^^^^ ------ ------
help: provide the arguments
|
LL - three_diff(T2::new(0));
LL + three_diff(/* T1 */, T2::new(0), /* T3 */);
|
LL | three_diff(/* T1 */, T2::new(0), /* T3 */);
| +++++++++ ++++++++++

error[E0308]: arguments to this function are incorrect
--> $DIR/issue-100478.rs:35:5
Expand Down Expand Up @@ -75,17 +74,8 @@ LL | fn foo(p1: T1, p2: Arc<T2>, p3: T3, p4: Arc<T4>, p5: T5, p6: T6, p7: T7, p8
| ^^^ -----------
help: provide the argument
|
LL ~ foo(
LL + p1,
LL + /* Arc<T2> */,
LL + p3,
LL + p4,
LL + p5,
LL + p6,
LL + p7,
LL + p8,
LL ~ );
|
LL | p1, /* Arc<T2> */
| +++++++++++++

error: aborting due to 4 previous errors

Expand Down
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