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Improve alias<->opaque unification logic
This commit is contained in:
Ayaz Hafiz
parent
a53ba3498b
commit
8b291854d3
2 changed files with 148 additions and 57 deletions
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@ -358,8 +358,11 @@ fn unify_context(subs: &mut Subs, pool: &mut Pool, ctx: Context) -> Outcome {
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Structure(flat_type) => {
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unify_structure(subs, pool, &ctx, flat_type, &ctx.second_desc.content)
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}
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Alias(symbol, args, real_var, kind) => {
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unify_alias(subs, pool, &ctx, *symbol, *args, *real_var, *kind)
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Alias(symbol, args, real_var, AliasKind::Structural) => {
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unify_alias(subs, pool, &ctx, *symbol, *args, *real_var)
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}
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Alias(symbol, args, real_var, AliasKind::Opaque) => {
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unify_opaque(subs, pool, &ctx, *symbol, *args, *real_var)
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}
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&RangedNumber(typ, range_vars) => unify_ranged_number(subs, pool, &ctx, typ, range_vars),
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Error => {
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@ -448,6 +451,56 @@ fn check_valid_range(
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}
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}
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#[inline(always)]
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fn unify_two_aliases(
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subs: &mut Subs,
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pool: &mut Pool,
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ctx: &Context,
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symbol: Symbol,
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args: AliasVariables,
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real_var: Variable,
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other_args: AliasVariables,
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other_real_var: Variable,
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other_content: &Content,
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) -> Outcome {
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if args.len() == other_args.len() {
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let mut outcome = Outcome::default();
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let it = args
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.all_variables()
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.into_iter()
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.zip(other_args.all_variables().into_iter());
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let args_unification_snapshot = subs.snapshot();
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for (l, r) in it {
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let l_var = subs[l];
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let r_var = subs[r];
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outcome.union(unify_pool(subs, pool, l_var, r_var, ctx.mode));
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}
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if outcome.mismatches.is_empty() {
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outcome.union(merge(subs, ctx, *other_content));
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}
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let args_unification_had_changes = !subs
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.vars_since_snapshot(&args_unification_snapshot)
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.is_empty();
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subs.commit_snapshot(args_unification_snapshot);
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if !args.is_empty() && args_unification_had_changes && outcome.mismatches.is_empty() {
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// We need to unify the real vars because unification of type variables
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// may have made them larger, which then needs to be reflected in the `real_var`.
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outcome.union(unify_pool(subs, pool, real_var, other_real_var, ctx.mode));
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}
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outcome
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} else {
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dbg!(args.len(), other_args.len());
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mismatch!("{:?}", symbol)
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}
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}
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// Unifies a structural alias
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#[inline(always)]
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fn unify_alias(
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subs: &mut Subs,
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@ -456,72 +509,40 @@ fn unify_alias(
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symbol: Symbol,
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args: AliasVariables,
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real_var: Variable,
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kind: AliasKind,
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) -> Outcome {
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let other_content = &ctx.second_desc.content;
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let either_is_opaque =
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kind == AliasKind::Opaque || matches!(other_content, Alias(_, _, _, AliasKind::Opaque));
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let kind = AliasKind::Structural;
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match other_content {
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FlexVar(_) => {
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// Alias wins
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merge(subs, ctx, Alias(symbol, args, real_var, kind))
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}
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RecursionVar { structure, .. } if !either_is_opaque => {
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unify_pool(subs, pool, real_var, *structure, ctx.mode)
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RecursionVar { structure, .. } => unify_pool(subs, pool, real_var, *structure, ctx.mode),
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RigidVar(_) | RigidAbleVar(..) | FlexAbleVar(..) => {
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unify_pool(subs, pool, real_var, ctx.second, ctx.mode)
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}
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RigidVar(_) | RigidAbleVar(..) => unify_pool(subs, pool, real_var, ctx.second, ctx.mode),
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FlexAbleVar(_, ability) if kind == AliasKind::Opaque && args.is_empty() => {
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// Opaque type wins
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let mut outcome = merge(subs, ctx, Alias(symbol, args, real_var, kind));
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outcome.must_implement_ability.push(MustImplementAbility { typ: symbol, ability: *ability });
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outcome
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}
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Alias(other_symbol, other_args, other_real_var, _)
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// Opaques types are only equal if the opaque symbols are equal!
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if !either_is_opaque || symbol == *other_symbol =>
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{
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Alias(_, _, _, AliasKind::Opaque) => unify_pool(subs, pool, real_var, ctx.second, ctx.mode),
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Alias(other_symbol, other_args, other_real_var, AliasKind::Structural) => {
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if symbol == *other_symbol {
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if args.len() == other_args.len() {
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let mut outcome = Outcome::default();
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let it = args
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.all_variables()
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.into_iter()
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.zip(other_args.all_variables().into_iter());
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let args_unification_snapshot = subs.snapshot();
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for (l, r) in it {
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let l_var = subs[l];
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let r_var = subs[r];
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outcome.union(unify_pool(subs, pool, l_var, r_var, ctx.mode));
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}
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if outcome.mismatches.is_empty() {
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outcome.union(merge(subs, ctx, *other_content));
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}
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let args_unification_had_changes = !subs.vars_since_snapshot(&args_unification_snapshot).is_empty();
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subs.commit_snapshot(args_unification_snapshot);
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if !args.is_empty() && args_unification_had_changes && outcome.mismatches.is_empty() {
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// We need to unify the real vars because unification of type variables
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// may have made them larger, which then needs to be reflected in the `real_var`.
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outcome.union(unify_pool(subs, pool, real_var, *other_real_var, ctx.mode));
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}
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outcome
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} else {
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dbg!(args.len(), other_args.len());
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mismatch!("{:?}", symbol)
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}
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unify_two_aliases(
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subs,
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pool,
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ctx,
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symbol,
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args,
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real_var,
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*other_args,
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*other_real_var,
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other_content,
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)
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} else {
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unify_pool(subs, pool, real_var, *other_real_var, ctx.mode)
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}
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}
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Structure(_) if !either_is_opaque => unify_pool(subs, pool, real_var, ctx.second, ctx.mode),
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RangedNumber(other_real_var, other_range_vars) if !either_is_opaque => {
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Structure(_) => unify_pool(subs, pool, real_var, ctx.second, ctx.mode),
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RangedNumber(other_real_var, other_range_vars) => {
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let outcome = unify_pool(subs, pool, real_var, *other_real_var, ctx.mode);
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if outcome.mismatches.is_empty() {
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check_valid_range(subs, pool, real_var, *other_range_vars, ctx.mode)
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@ -530,9 +551,60 @@ fn unify_alias(
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}
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}
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Error => merge(subs, ctx, Error),
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}
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}
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#[inline(always)]
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fn unify_opaque(
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subs: &mut Subs,
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pool: &mut Pool,
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ctx: &Context,
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symbol: Symbol,
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args: AliasVariables,
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real_var: Variable,
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) -> Outcome {
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let other_content = &ctx.second_desc.content;
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let kind = AliasKind::Opaque;
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match other_content {
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FlexVar(_) => {
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// Alias wins
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merge(subs, ctx, Alias(symbol, args, real_var, kind))
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}
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RigidVar(_) | RigidAbleVar(..) => unify_pool(subs, pool, real_var, ctx.second, ctx.mode),
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FlexAbleVar(_, ability) if args.is_empty() => {
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// Opaque type wins
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let mut outcome = merge(subs, ctx, Alias(symbol, args, real_var, kind));
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outcome.must_implement_ability.push(MustImplementAbility {
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typ: symbol,
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ability: *ability,
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});
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outcome
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}
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Alias(_, _, other_real_var, AliasKind::Structural) => {
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unify_pool(subs, pool, ctx.first, *other_real_var, ctx.mode)
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}
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Alias(other_symbol, other_args, other_real_var, AliasKind::Opaque) => {
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// Opaques types are only equal if the opaque symbols are equal!
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if symbol == *other_symbol {
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unify_two_aliases(
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subs,
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pool,
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ctx,
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symbol,
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args,
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real_var,
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*other_args,
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*other_real_var,
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other_content,
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)
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} else {
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mismatch!("{:?}", symbol)
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}
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}
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other => {
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// The type on the left is an alias, but the one on the right is not!
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debug_assert!(either_is_opaque);
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// The type on the left is an opaque, but the one on the right is not!
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mismatch!("Cannot unify opaque {:?} with {:?}", symbol, other)
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}
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}
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