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Centralize the decision to suggest patterns vs _

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This commit is contained in:
Nadrieril 2024-03-12 21:49:29 +01:00
parent b878ab6a27
commit 1b31e14a31
1 changed files with 36 additions and 40 deletions
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76
compiler/rustc_mir_build/src/thir/pattern/check_match.rs
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@ -939,9 +939,6 @@ fn report_non_exhaustive_match<'p, 'tcx>(
};
// In the case of an empty match, replace the '`_` not covered' diagnostic with something more
// informative.
let mut err;
let pattern;
let patterns_len;
if is_empty_match && !non_empty_enum {
return cx.tcx.dcx().emit_err(NonExhaustivePatternsTypeNotEmpty {
cx,
@ -949,33 +946,23 @@ fn report_non_exhaustive_match<'p, 'tcx>(
span: sp,
ty: scrut_ty,
});
} else {
// FIXME: migration of this diagnostic will require list support
let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
err = create_e0004(
cx.tcx.sess,
sp,
format!("non-exhaustive patterns: {joined_patterns} not covered"),
);
err.span_label(
sp,
format!(
"pattern{} {} not covered",
rustc_errors::pluralize!(witnesses.len()),
joined_patterns
),
);
patterns_len = witnesses.len();
pattern = if witnesses.len() < 4 {
witnesses
.iter()
.map(|witness| cx.hoist_witness_pat(witness).to_string())
.collect::<Vec<String>>()
.join(" | ")
} else {
"_".to_string()
};
};
}
// FIXME: migration of this diagnostic will require list support
let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
let mut err = create_e0004(
cx.tcx.sess,
sp,
format!("non-exhaustive patterns: {joined_patterns} not covered"),
);
err.span_label(
sp,
format!(
"pattern{} {} not covered",
rustc_errors::pluralize!(witnesses.len()),
joined_patterns
),
);
// Point at the definition of non-covered `enum` variants.
if let Some(AdtDefinedHere { adt_def_span, ty, variants }) =
@ -1022,16 +1009,25 @@ fn report_non_exhaustive_match<'p, 'tcx>(
}
}
// Whether we suggest the actual missing patterns or `_`.
let suggest_the_witnesses = witnesses.len() < 4;
let suggested_arm = if suggest_the_witnesses {
let pattern = witnesses
.iter()
.map(|witness| cx.hoist_witness_pat(witness).to_string())
.collect::<Vec<String>>()
.join(" | ");
if witnesses.iter().all(|p| p.is_never_pattern()) && cx.tcx.features().never_patterns {
// Arms with a never pattern don't take a body.
pattern
} else {
format!("{pattern} => todo!()")
}
} else {
format!("_ => todo!()")
};
let mut suggestion = None;
let sm = cx.tcx.sess.source_map();
let suggested_arm = if witnesses.len() < 4
&& witnesses.iter().all(|p| p.is_never_pattern())
&& cx.tcx.features().never_patterns
{
pattern
} else {
format!("{pattern} => todo!()")
};
match arms {
[] if sp.eq_ctxt(expr_span) => {
// Get the span for the empty match body `{}`.
@ -1102,13 +1098,13 @@ fn report_non_exhaustive_match<'p, 'tcx>(
let msg = format!(
"ensure that all possible cases are being handled by adding a match arm with a wildcard \
pattern{}{}",
if patterns_len > 1 && patterns_len < 4 && suggestion.is_some() {
if witnesses.len() > 1 && suggest_the_witnesses && suggestion.is_some() {
", a match arm with multiple or-patterns"
} else {
// we are either not suggesting anything, or suggesting `_`
""
},
match patterns_len {
match witnesses.len() {
// non-exhaustive enum case
0 if suggestion.is_some() => " as shown",
0 => "",