bjoernager/rust
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Use a separate pattern type for rustc_pattern_analysis diagnostics

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The pattern-analysis code needs to print patterns, as part of its user-visible
diagnostics. But it never actually tries to print "real" patterns! Instead, it
only ever prints synthetic patterns that it has reconstructed from its own
internal represenations.

We can therefore simultaneously remove two obstacles to changing `thir::Pat`,
by having the pattern-analysis code use its own dedicated type for building
printable patterns, and then making `thir::Pat` not printable at all.
This commit is contained in:
Zalathar 2024-07-30 22:44:02 +10:00
parent a9ea85e044
commit dd5a8d7714
3 changed files with 209 additions and 169 deletions
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159
compiler/rustc_middle/src/thir.rs
View file

@ -28,7 +28,7 @@ use rustc_middle::ty::{
TyCtxt, UpvarArgs,
};
use rustc_span::def_id::LocalDefId;
use rustc_span::{sym, ErrorGuaranteed, Span, Symbol, DUMMY_SP};
use rustc_span::{ErrorGuaranteed, Span, Symbol};
use rustc_target::abi::{FieldIdx, Integer, Size, VariantIdx};
use rustc_target::asm::InlineAsmRegOrRegClass;
use tracing::instrument;
@ -597,10 +597,6 @@ pub struct Pat<'tcx> {
}
impl<'tcx> Pat<'tcx> {
pub fn wildcard_from_ty(ty: Ty<'tcx>) -> Self {
Pat { ty, span: DUMMY_SP, kind: PatKind::Wild }
}
pub fn simple_ident(&self) -> Option<Symbol> {
match self.kind {
PatKind::Binding {
@ -1073,159 +1069,6 @@ impl<'tcx> PatRangeBoundary<'tcx> {
}
}
impl<'tcx> fmt::Display for Pat<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Printing lists is a chore.
let mut first = true;
let mut start_or_continue = |s| {
if first {
first = false;
""
} else {
s
}
};
let mut start_or_comma = || start_or_continue(", ");
match self.kind {
PatKind::Wild => write!(f, "_"),
PatKind::Never => write!(f, "!"),
PatKind::AscribeUserType { ref subpattern, .. } => write!(f, "{subpattern}: _"),
PatKind::Binding { name, mode, ref subpattern, .. } => {
f.write_str(mode.prefix_str())?;
write!(f, "{name}")?;
if let Some(ref subpattern) = *subpattern {
write!(f, " @ {subpattern}")?;
}
Ok(())
}
PatKind::Variant { ref subpatterns, .. } | PatKind::Leaf { ref subpatterns } => {
let variant_and_name = match self.kind {
PatKind::Variant { adt_def, variant_index, .. } => ty::tls::with(|tcx| {
let variant = adt_def.variant(variant_index);
let adt_did = adt_def.did();
let name = if tcx.get_diagnostic_item(sym::Option) == Some(adt_did)
|| tcx.get_diagnostic_item(sym::Result) == Some(adt_did)
{
variant.name.to_string()
} else {
format!("{}::{}", tcx.def_path_str(adt_def.did()), variant.name)
};
Some((variant, name))
}),
_ => self.ty.ty_adt_def().and_then(|adt_def| {
if !adt_def.is_enum() {
ty::tls::with(|tcx| {
Some((adt_def.non_enum_variant(), tcx.def_path_str(adt_def.did())))
})
} else {
None
}
}),
};
if let Some((variant, name)) = &variant_and_name {
write!(f, "{name}")?;
// Only for Adt we can have `S {...}`,
// which we handle separately here.
if variant.ctor.is_none() {
write!(f, " {{ ")?;
let mut printed = 0;
for p in subpatterns {
if let PatKind::Wild = p.pattern.kind {
continue;
}
let name = variant.fields[p.field].name;
write!(f, "{}{}: {}", start_or_comma(), name, p.pattern)?;
printed += 1;
}
let is_union = self.ty.ty_adt_def().is_some_and(|adt| adt.is_union());
if printed < variant.fields.len() && (!is_union || printed == 0) {
write!(f, "{}..", start_or_comma())?;
}
return write!(f, " }}");
}
}
let num_fields =
variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
if num_fields != 0 || variant_and_name.is_none() {
write!(f, "(")?;
for i in 0..num_fields {
write!(f, "{}", start_or_comma())?;
// Common case: the field is where we expect it.
if let Some(p) = subpatterns.get(i) {
if p.field.index() == i {
write!(f, "{}", p.pattern)?;
continue;
}
}
// Otherwise, we have to go looking for it.
if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
write!(f, "{}", p.pattern)?;
} else {
write!(f, "_")?;
}
}
write!(f, ")")?;
}
Ok(())
}
PatKind::Deref { ref subpattern } => {
match self.ty.kind() {
ty::Adt(def, _) if def.is_box() => write!(f, "box ")?,
ty::Ref(_, _, mutbl) => {
write!(f, "&{}", mutbl.prefix_str())?;
}
_ => bug!("{} is a bad Deref pattern type", self.ty),
}
write!(f, "{subpattern}")
}
PatKind::DerefPattern { ref subpattern, .. } => {
write!(f, "deref!({subpattern})")
}
PatKind::Constant { value } => write!(f, "{value}"),
PatKind::InlineConstant { def: _, ref subpattern } => {
write!(f, "{} (from inline const)", subpattern)
}
PatKind::Range(ref range) => write!(f, "{range}"),
PatKind::Slice { ref prefix, ref slice, ref suffix }
| PatKind::Array { ref prefix, ref slice, ref suffix } => {
write!(f, "[")?;
for p in prefix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
if let Some(ref slice) = *slice {
write!(f, "{}", start_or_comma())?;
match slice.kind {
PatKind::Wild => {}
_ => write!(f, "{slice}")?,
}
write!(f, "..")?;
}
for p in suffix.iter() {
write!(f, "{}{}", start_or_comma(), p)?;
}
write!(f, "]")
}
PatKind::Or { ref pats } => {
for pat in pats.iter() {
write!(f, "{}{}", start_or_continue(" | "), pat)?;
}
Ok(())
}
PatKind::Error(_) => write!(f, "<error>"),
}
}
}
// Some nodes are used a lot. Make sure they don't unintentionally get bigger.
#[cfg(target_pointer_width = "64")]
mod size_asserts {