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Fix indices and remove some unwraps in arg mismatch algorithm #97557

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merged 3 commits into from
Jun 9, 2022
Merged

Fix indices and remove some unwraps in arg mismatch algorithm #97557

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6c9bd8d
fix indexing and remove some unwraps from arg mismatch diagnostic
compiler-errors May 30, 2022
fc93461
fix typo
compiler-errors May 30, 2022
4b26d41
add regression test
compiler-errors May 30, 2022
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43 changes: 25 additions & 18 deletions compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -445,16 +445,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let found_errors = !errors.is_empty();

errors.drain_filter(|error| {
let Error::Invalid(input_idx, arg_idx, Compatibility::Incompatible(error)) = error else { return false };
let Error::Invalid(input_idx, arg_idx, Compatibility::Incompatible(Some(e))) = error else { return false };
let expected_ty = expected_input_tys[*arg_idx];
let provided_ty = final_arg_types[*input_idx].map(|ty| ty.0).unwrap();
let provided_ty = final_arg_types[*input_idx].map(|ty| ty.0).unwrap_or_else(|| tcx.ty_error());
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final_arg_types is a vector of length provided_args.len(), but is only populated with Some (by demand_compatible) up to expected_input_tys.len(). This unwrap was panicking in a bunch of cases.

let cause = &self.misc(provided_args[*input_idx].span);
let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
if let Some(e) = error {
if !matches!(trace.cause.as_failure_code(e), FailureCode::Error0308(_)) {
self.report_and_explain_type_error(trace, e).emit();
return true;
}
if !matches!(trace.cause.as_failure_code(e), FailureCode::Error0308(_)) {
self.report_and_explain_type_error(trace, e).emit();
return true;
}
false
});
Expand Down Expand Up @@ -585,7 +583,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
)) = errors.iter().next()
{
let expected_ty = expected_input_tys[*arg_idx];
let provided_ty = final_arg_types[*arg_idx].map(|ty| ty.0).unwrap();
let provided_ty = final_arg_types[*input_idx]
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@compiler-errors compiler-errors May 30, 2022 •
edited
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Should be using input_idx. Not sure if this is "correct" (though I think it is), but regardless, if there are more expected args than provided args, then using arg_idx might be out of bounds.

.map(|ty| ty.0)
.unwrap_or_else(|| tcx.ty_error());
let expected_ty = self.resolve_vars_if_possible(expected_ty);
let provided_ty = self.resolve_vars_if_possible(provided_ty);
let cause = &self.misc(provided_args[*input_idx].span);
Expand All @@ -595,7 +595,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
&mut err,
&provided_args[*input_idx],
provided_ty,
final_arg_types[*input_idx].map(|ty| ty.1).unwrap(),
final_arg_types[*input_idx]
.map(|ty| ty.1)
.unwrap_or_else(|| tcx.ty_error()),
None,
None,
);
Expand Down Expand Up @@ -652,7 +654,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
match error {
Error::Invalid(input_idx, arg_idx, compatibility) => {
let expected_ty = expected_input_tys[arg_idx];
let provided_ty = final_arg_types[input_idx].map(|ty| ty.0).unwrap();
let provided_ty = final_arg_types[input_idx]
.map(|ty| ty.0)
.unwrap_or_else(|| tcx.ty_error());
let expected_ty = self.resolve_vars_if_possible(expected_ty);
let provided_ty = self.resolve_vars_if_possible(provided_ty);
if let Compatibility::Incompatible(error) = &compatibility {
Expand All @@ -674,8 +678,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.emit_coerce_suggestions(
&mut err,
&provided_args[input_idx],
final_arg_types[input_idx].map(|ty| ty.0).unwrap(),
final_arg_types[input_idx].map(|ty| ty.1).unwrap(),
provided_ty,
// FIXME(compiler-errors): expected_ty?
final_arg_types[input_idx]
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@compiler-errors compiler-errors May 30, 2022 •
edited
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This should actually probably be expected_ty instead of final_arg_types[input_idx].1, but this will just provide a bad suggestion, and not panic.

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What about changing emit_coerce_suggestions to take an Option here instead (and make it not emit the invalid suggestion when it is None)?

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but emit_coerce_suggestions can't do anything if we don't have a target type to coerce to, right?

.map(|ty| ty.1)
.unwrap_or_else(|| tcx.ty_error()),
None,
None,
);
Expand Down Expand Up @@ -860,7 +867,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let first_expected_ty =
self.resolve_vars_if_possible(expected_input_tys[arg_idx]);
let first_provided_ty = if let Some((ty, _)) = final_arg_types[input_idx] {
format!(",found `{}`", ty)
format!(", found `{}`", ty)
} else {
String::new()
};
Expand All @@ -872,7 +879,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.resolve_vars_if_possible(expected_input_tys[other_arg_idx]);
let other_provided_ty =
if let Some((ty, _)) = final_arg_types[other_input_idx] {
format!(",found `{}`", ty)
format!(", found `{}`", ty)
} else {
String::new()
};
Expand All @@ -888,14 +895,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Error::Permutation(args) => {
for (dst_arg, dest_input) in args {
let expected_ty =
self.resolve_vars_if_possible(expected_input_tys[dest_input]);
let provided_ty = if let Some((ty, _)) = final_arg_types[dst_arg] {
format!(",found `{}`", ty)
self.resolve_vars_if_possible(expected_input_tys[dst_arg]);
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I think these were swapped -- dst_arg is an "expected argument"-like index, and dst_input is a "provided argument"-like index.

let provided_ty = if let Some((ty, _)) = final_arg_types[dest_input] {
format!(", found `{}`", ty)
} else {
String::new()
};
labels.push((
provided_args[dst_arg].span,
provided_args[dest_input].span,
format!("expected `{}`{}", expected_ty, provided_ty),
));
}
Expand Down
10 changes: 5 additions & 5 deletions src/test/ui/argument-suggestions/basic.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -48,9 +48,9 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/basic.rs:23:5
|
LL | swapped("", 1);
| ^^^^^^^ -- - expected `&str`,found `{integer}`
| ^^^^^^^ -- - expected `&str`, found `{integer}`
| |
| expected `u32`,found `&'static str`
| expected `u32`, found `&'static str`
|
note: function defined here
--> $DIR/basic.rs:16:4
Expand All @@ -66,10 +66,10 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/basic.rs:24:5
|
LL | permuted(Y {}, Z {}, X {});
| ^^^^^^^^ ---- ---- ---- expected `Z`,found `X`
| ^^^^^^^^ ---- ---- ---- expected `Z`, found `X`
| | |
| | expected `Y`,found `Z`
| expected `X`,found `Y`
| | expected `Y`, found `Z`
| expected `X`, found `Y`
|
note: function defined here
--> $DIR/basic.rs:17:4
Expand Down
14 changes: 14 additions & 0 deletions src/test/ui/argument-suggestions/issue-97484.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
struct A;
struct B;
struct C;
struct D;
struct E;
struct F;
struct G;

fn foo(a: &A, d: D, e: &E, g: G) {}

fn main() {
foo(&&A, B, C, D, E, F, G);
//~^ ERROR this function takes 4 arguments but 7 arguments were supplied
}
27 changes: 27 additions & 0 deletions src/test/ui/argument-suggestions/issue-97484.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
error[E0061]: this function takes 4 arguments but 7 arguments were supplied
--> $DIR/issue-97484.rs:12:5
|
LL | foo(&&A, B, C, D, E, F, G);
| ^^^ - - - argument unexpected
| | |
| | argument of type `&E` unexpected
| argument of type `D` unexpected
|
note: function defined here
--> $DIR/issue-97484.rs:9:4
|
LL | fn foo(a: &A, d: D, e: &E, g: G) {}
| ^^^ ----- ---- ----- ----
help: consider removing the ``
|
LL - foo(&&A, B, C, D, E, F, G);
LL + foo(&&A, B, C, D, E, F, G);
|
Comment on lines +15 to +19
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This is buggy (which, fair, you're sidestepping the ICE). Given that after this we suggest removing some args, it tells me that we can better handle this case to not emit it at all.

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I actually know how to fix this one, and I think I fixed it on the more extensive fix.

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The technical explanation is that we're trying to coerce &&A into &&A, and the current suggestion logic goes "ah yes, dereference it zero times" (well, actually, remove & zero times).

help: remove the extra arguments
|
LL | foo(&&A, D, {&E}, G);
| ~~~~~~~~~~~~~~~~~~~~
Comment on lines +20 to +23
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This tells me that we should teach the suggestion to add and remove borrows as well :)

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This should fall out of coercion suggestions which we attempt when we see an "invalid" argument.


error: aborting due to previous error

For more information about this error, try `rustc --explain E0061`.
8 changes: 4 additions & 4 deletions src/test/ui/argument-suggestions/mixed_cases.stderr
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Expand Up @@ -76,10 +76,10 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/mixed_cases.rs:20:3
|
LL | three_args("", X {}, 1);
| ^^^^^^^^^^ -- ---- - expected `&str`,found `{integer}`
| ^^^^^^^^^^ -- ---- - expected `&str`, found `{integer}`
| | |
| | expected `f32`, found struct `X`
| expected `i32`,found `&'static str`
| expected `i32`, found `&'static str`
|
note: function defined here
--> $DIR/mixed_cases.rs:6:4
Expand All @@ -98,8 +98,8 @@ LL | three_args("", 1);
| ^^^^^^^^^^ -- -
| | |
| | an argument of type `f32` is missing
| | expected `&str`,found `{integer}`
| expected `i32`,found `&'static str`
| | expected `&str`, found `{integer}`
| expected `i32`, found `&'static str`
|
note: function defined here
--> $DIR/mixed_cases.rs:6:4
Expand Down
16 changes: 8 additions & 8 deletions src/test/ui/argument-suggestions/permuted_arguments.stderr
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Expand Up @@ -2,10 +2,10 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/permuted_arguments.rs:10:3
|
LL | three_args(1.0, "", 1);
| ^^^^^^^^^^ --- -- - expected `&str`,found `{integer}`
| ^^^^^^^^^^ --- -- - expected `&str`, found `{integer}`
| | |
| | expected `f32`,found `&'static str`
| expected `i32`,found `{float}`
| | expected `f32`, found `&'static str`
| expected `i32`, found `{float}`
|
note: function defined here
--> $DIR/permuted_arguments.rs:5:4
Expand All @@ -21,12 +21,12 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/permuted_arguments.rs:12:3
|
LL | many_args(X {}, Y {}, 1, 1.0, "");
| ^^^^^^^^^ ---- ---- - --- -- expected `Y`,found `&'static str`
| ^^^^^^^^^ ---- ---- - --- -- expected `Y`, found `&'static str`
| | | | |
| | | | expected `X`,found `{float}`
| | | expected `&str`,found `{integer}`
| | expected `f32`,found `Y`
| expected `i32`,found `X`
| | | | expected `X`, found `{float}`
| | | expected `&str`, found `{integer}`
| | expected `f32`, found `Y`
| expected `i32`, found `X`
|
note: function defined here
--> $DIR/permuted_arguments.rs:6:4
Expand Down
24 changes: 12 additions & 12 deletions src/test/ui/argument-suggestions/swapped_arguments.stderr
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Expand Up @@ -2,9 +2,9 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/swapped_arguments.rs:8:3
|
LL | two_args(1.0, 1);
| ^^^^^^^^ --- - expected `f32`,found `{integer}`
| ^^^^^^^^ --- - expected `f32`, found `{integer}`
| |
| expected `i32`,found `{float}`
| expected `i32`, found `{float}`
|
note: function defined here
--> $DIR/swapped_arguments.rs:3:4
Expand All @@ -20,9 +20,9 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/swapped_arguments.rs:9:3
|
LL | three_args(1.0, 1, "");
| ^^^^^^^^^^ --- - expected `f32`,found `{integer}`
| ^^^^^^^^^^ --- - expected `f32`, found `{integer}`
| |
| expected `i32`,found `{float}`
| expected `i32`, found `{float}`
|
note: function defined here
--> $DIR/swapped_arguments.rs:4:4
Expand All @@ -38,9 +38,9 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/swapped_arguments.rs:10:3
|
LL | three_args( 1, "", 1.0);
| ^^^^^^^^^^ -- --- expected `&str`,found `{float}`
| ^^^^^^^^^^ -- --- expected `&str`, found `{float}`
| |
| expected `f32`,found `&'static str`
| expected `f32`, found `&'static str`
|
note: function defined here
--> $DIR/swapped_arguments.rs:4:4
Expand All @@ -56,9 +56,9 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/swapped_arguments.rs:11:3
|
LL | three_args( "", 1.0, 1);
| ^^^^^^^^^^ -- - expected `&str`,found `{integer}`
| ^^^^^^^^^^ -- - expected `&str`, found `{integer}`
| |
| expected `i32`,found `&'static str`
| expected `i32`, found `&'static str`
|
note: function defined here
--> $DIR/swapped_arguments.rs:4:4
Expand All @@ -74,11 +74,11 @@ error[E0308]: arguments to this function are incorrect
--> $DIR/swapped_arguments.rs:13:3
|
LL | four_args(1.0, 1, X {}, "");
| ^^^^^^^^^ --- - ---- -- expected `X`,found `&'static str`
| ^^^^^^^^^ --- - ---- -- expected `X`, found `&'static str`
| | | |
| | | expected `&str`,found `X`
| | expected `f32`,found `{integer}`
| expected `i32`,found `{float}`
| | | expected `&str`, found `X`
| | expected `f32`, found `{integer}`
| expected `i32`, found `{float}`
|
note: function defined here
--> $DIR/swapped_arguments.rs:5:4
Expand Down