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Merge pull request #3600 from rtfeldman/i3298
Various improvements to is-open constraints/catch-all branches in patterns
This commit is contained in:
Folkert de Vries
GitHub
commit
860df057dc
@ -2705,7 +2705,7 @@ pub mod test_constrain {
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A _ -> Z
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"#
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),
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"[A [M, N]*] -> [X, Y, Z]*",
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"[A [M, N]] -> [X, Y, Z]*",
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)
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}
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@ -735,7 +735,8 @@ pub fn constrain_expr(
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let mut pattern_vars = Vec::with_capacity(branches.len());
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let mut pattern_headers = SendMap::default();
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let mut pattern_cons = Vec::with_capacity(branches.len() + 2);
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let mut branch_cons = Vec::with_capacity(branches.len());
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let mut delayed_is_open_constraints = Vec::with_capacity(2);
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let mut body_cons = Vec::with_capacity(branches.len());
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for (index, when_branch) in branches.iter().enumerate() {
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let expected_pattern = |sub_pattern, sub_region| {
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@ -749,19 +750,24 @@ pub fn constrain_expr(
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)
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};
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let (new_pattern_vars, new_pattern_headers, pattern_con, branch_con) =
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constrain_when_branch_help(
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constraints,
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env,
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region,
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when_branch,
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expected_pattern,
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branch_expr_reason(
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&expected,
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HumanIndex::zero_based(index),
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when_branch.value.region,
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),
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);
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let ConstrainedBranch {
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vars: new_pattern_vars,
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headers: new_pattern_headers,
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pattern_constraints,
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is_open_constrains,
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body_constraints,
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} = constrain_when_branch_help(
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constraints,
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env,
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region,
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when_branch,
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expected_pattern,
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branch_expr_reason(
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&expected,
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HumanIndex::zero_based(index),
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when_branch.value.region,
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),
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);
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pattern_vars.extend(new_pattern_vars);
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@ -779,9 +785,10 @@ pub fn constrain_expr(
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}
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pattern_headers.extend(new_pattern_headers);
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pattern_cons.push(pattern_con);
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pattern_cons.push(pattern_constraints);
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delayed_is_open_constraints.extend(is_open_constrains);
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branch_cons.push(branch_con);
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body_cons.push(body_constraints);
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}
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// Deviation: elm adds another layer of And nesting
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@ -793,6 +800,11 @@ pub fn constrain_expr(
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// The return type of each branch must equal the return type of
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// the entire when-expression.
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// Layer on the "is-open" constraints at the very end, after we know what the branch
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// types are supposed to look like without open-ness.
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let is_open_constr = constraints.and_constraint(delayed_is_open_constraints);
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pattern_cons.push(is_open_constr);
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// After solving the condition variable with what's expected from the branch patterns,
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// check it against the condition expression.
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//
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@ -826,7 +838,7 @@ pub fn constrain_expr(
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// Solve all the pattern constraints together, introducing variables in the pattern as
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// need be before solving the bodies.
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let pattern_constraints = constraints.and_constraint(pattern_cons);
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let body_constraints = constraints.and_constraint(branch_cons);
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let body_constraints = constraints.and_constraint(body_cons);
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let when_body_con = constraints.let_constraint(
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[],
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pattern_vars,
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@ -1790,6 +1802,14 @@ fn constrain_value_def(
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}
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}
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struct ConstrainedBranch {
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vars: Vec<Variable>,
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headers: VecMap<Symbol, Loc<Type>>,
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pattern_constraints: Constraint,
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is_open_constrains: Vec<Constraint>,
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body_constraints: Constraint,
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}
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/// Constrain a when branch, returning (variables in pattern, symbols introduced in pattern, pattern constraint, body constraint).
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/// We want to constraint all pattern constraints in a "when" before body constraints.
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#[inline(always)]
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@ -1800,12 +1820,7 @@ fn constrain_when_branch_help(
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when_branch: &WhenBranch,
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pattern_expected: impl Fn(HumanIndex, Region) -> PExpected<Type>,
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expr_expected: Expected<Type>,
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) -> (
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Vec<Variable>,
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VecMap<Symbol, Loc<Type>>,
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Constraint,
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Constraint,
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) {
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) -> ConstrainedBranch {
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let ret_constraint = constrain_expr(
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constraints,
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env,
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@ -1869,41 +1884,43 @@ fn constrain_when_branch_help(
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}
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}
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let (pattern_constraints, body_constraints) = if let Some(loc_guard) = &when_branch.guard {
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let guard_constraint = constrain_expr(
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constraints,
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env,
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region,
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&loc_guard.value,
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Expected::ForReason(
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Reason::WhenGuard,
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Type::Variable(Variable::BOOL),
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loc_guard.region,
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),
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);
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let (pattern_constraints, delayed_is_open_constraints, body_constraints) =
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if let Some(loc_guard) = &when_branch.guard {
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let guard_constraint = constrain_expr(
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constraints,
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env,
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region,
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&loc_guard.value,
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Expected::ForReason(
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Reason::WhenGuard,
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Type::Variable(Variable::BOOL),
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loc_guard.region,
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),
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);
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// must introduce the headers from the pattern before constraining the guard
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state
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.constraints
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.append(&mut state.delayed_is_open_constraints);
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let state_constraints = constraints.and_constraint(state.constraints);
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let inner = constraints.let_constraint([], [], [], guard_constraint, ret_constraint);
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// must introduce the headers from the pattern before constraining the guard
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let delayed_is_open_constraints = state.delayed_is_open_constraints;
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let state_constraints = constraints.and_constraint(state.constraints);
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let inner = constraints.let_constraint([], [], [], guard_constraint, ret_constraint);
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(state_constraints, inner)
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} else {
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state
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.constraints
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.append(&mut state.delayed_is_open_constraints);
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let state_constraints = constraints.and_constraint(state.constraints);
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(state_constraints, ret_constraint)
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};
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(state_constraints, delayed_is_open_constraints, inner)
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} else {
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let delayed_is_open_constraints = state.delayed_is_open_constraints;
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let state_constraints = constraints.and_constraint(state.constraints);
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(
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state_constraints,
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delayed_is_open_constraints,
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ret_constraint,
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)
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};
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(
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state.vars,
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state.headers,
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ConstrainedBranch {
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vars: state.vars,
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headers: state.headers,
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pattern_constraints,
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is_open_constrains: delayed_is_open_constraints,
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body_constraints,
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)
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}
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}
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fn constrain_field(
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@ -498,9 +498,6 @@ pub fn constrain_pattern(
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state.vars.push(*ext_var);
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state.constraints.push(whole_con);
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state.constraints.push(tag_con);
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state
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.constraints
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.append(&mut state.delayed_is_open_constraints);
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}
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UnwrappedOpaque {
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@ -1653,25 +1653,35 @@ fn open_tag_union(subs: &mut Subs, var: Variable) {
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use {Content::*, FlatType::*};
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let desc = subs.get(var);
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if let Structure(TagUnion(tags, ext)) = desc.content {
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if let Structure(EmptyTagUnion) = subs.get_content_without_compacting(ext) {
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let new_ext = subs.fresh_unnamed_flex_var();
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subs.set_rank(new_ext, desc.rank);
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let new_union = Structure(TagUnion(tags, new_ext));
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subs.set_content(var, new_union);
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match desc.content {
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Structure(TagUnion(tags, ext)) => {
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if let Structure(EmptyTagUnion) = subs.get_content_without_compacting(ext) {
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let new_ext = subs.fresh_unnamed_flex_var();
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subs.set_rank(new_ext, desc.rank);
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let new_union = Structure(TagUnion(tags, new_ext));
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subs.set_content(var, new_union);
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}
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// Also open up all nested tag unions.
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let all_vars = tags.variables().into_iter();
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stack.extend(all_vars.flat_map(|slice| subs[slice]).map(|var| subs[var]));
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}
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// Also open up all nested tag unions.
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let all_vars = tags.variables().into_iter();
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stack.extend(all_vars.flat_map(|slice| subs[slice]).map(|var| subs[var]));
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Structure(Record(fields, _)) => {
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// Open up all nested tag unions.
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stack.extend(subs.get_subs_slice(fields.variables()));
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}
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_ => {
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// Everything else is not a structural type that can be opened
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// (i.e. cannot be matched in a pattern-match)
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}
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}
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// Today, an "open" constraint doesn't affect any types
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// other than tag unions. Recursive tag unions are constructed
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// at a later time (during occurs checks after tag unions are
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// resolved), so that's not handled here either.
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// NB: Handle record types here if we add presence constraints
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// to their type inference as well.
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}
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}
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@ -245,7 +245,13 @@ mod solve_expr {
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assert_eq!(actual, expected.to_string());
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}
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fn infer_queries_help(src: &str, expected: impl FnOnce(&str), print_only_under_alias: bool) {
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#[derive(Default)]
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struct InferOptions {
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print_only_under_alias: bool,
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allow_errors: bool,
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}
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fn infer_queries_help(src: &str, expected: impl FnOnce(&str), options: InferOptions) {
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let (
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LoadedModule {
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module_id: home,
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@ -269,12 +275,14 @@ mod solve_expr {
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let (can_problems, type_problems) =
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format_problems(&src, home, &interns, can_problems, type_problems);
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assert!(
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can_problems.is_empty(),
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"Canonicalization problems: {}",
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can_problems
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);
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assert!(type_problems.is_empty(), "Type problems: {}", type_problems);
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if !options.allow_errors {
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assert!(
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can_problems.is_empty(),
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"Canonicalization problems: {}",
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can_problems
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);
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assert!(type_problems.is_empty(), "Type problems: {}", type_problems);
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}
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let queries = parse_queries(&src);
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assert!(!queries.is_empty(), "No queries provided!");
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@ -295,7 +303,7 @@ mod solve_expr {
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&interns,
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DebugPrint {
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print_lambda_sets: true,
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print_only_under_alias,
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print_only_under_alias: options.print_only_under_alias,
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},
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);
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subs.rollback_to(snapshot);
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@ -325,11 +333,10 @@ mod solve_expr {
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}
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macro_rules! infer_queries {
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($program:expr, @$queries:literal $(,)?) => {
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infer_queries_help($program, |golden| insta::assert_snapshot!(golden, @$queries), false)
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};
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($program:expr, @$queries:literal, print_only_under_alias=true $(,)?) => {
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infer_queries_help($program, |golden| insta::assert_snapshot!(golden, @$queries), true)
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($program:expr, @$queries:literal $($option:ident: $value:expr)*) => {
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infer_queries_help($program, |golden| insta::assert_snapshot!(golden, @$queries), InferOptions {
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$($option: $value,)* ..InferOptions::default()
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})
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};
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}
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@ -6662,7 +6669,7 @@ mod solve_expr {
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A#id(4) : A -[[id(4)]]-> A
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idChoice : a -[[] + a:id(2):1]-> a | a has Id
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idChoice : A -[[id(4)]]-> A
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"#,
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"#
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)
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}
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@ -6696,8 +6703,8 @@ mod solve_expr {
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A#id(5) : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
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Id#id(3) : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
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alias : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
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"#,
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print_only_under_alias = true,
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"#
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print_only_under_alias: true
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)
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}
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@ -6726,8 +6733,8 @@ mod solve_expr {
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@r#"
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A#id(5) : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
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it : {} -[[8(8)]]-> {}
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"#,
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print_only_under_alias = true,
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"#
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print_only_under_alias: true
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)
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}
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@ -6757,8 +6764,8 @@ mod solve_expr {
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@r#"
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A#id(5) : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
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A#id(5) : {} -[[id(5)]]-> ({} -[[8(8)]]-> {})
|
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"#,
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print_only_under_alias = true,
|
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"#
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print_only_under_alias: true
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)
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}
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@ -6895,8 +6902,8 @@ mod solve_expr {
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Named name outerList : [Named Str (List a)] as a
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name : Str
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outerList : List ([Named Str (List a)] as a)
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"#,
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print_only_under_alias = true
|
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"#
|
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print_only_under_alias: true
|
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)
|
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}
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|
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@ -7012,8 +7019,8 @@ mod solve_expr {
|
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#^^^{-1}
|
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"#
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),
|
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@r#"fun : {} -[[thunk(9) (({} -[[15(15)]]-> { s1 : Str })) ({ s1 : Str } -[[g(4)]]-> ({} -[[13(13) Str]]-> Str)), thunk(9) (({} -[[14(14)]]-> Str)) (Str -[[f(3)]]-> ({} -[[11(11)]]-> Str))]]-> Str"#,
|
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print_only_under_alias = true,
|
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@r#"fun : {} -[[thunk(9) (({} -[[15(15)]]-> { s1 : Str })) ({ s1 : Str } -[[g(4)]]-> ({} -[[13(13) Str]]-> Str)), thunk(9) (({} -[[14(14)]]-> Str)) (Str -[[f(3)]]-> ({} -[[11(11)]]-> Str))]]-> Str"#
|
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print_only_under_alias: true
|
||||
);
|
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}
|
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|
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@ -7402,4 +7409,35 @@ mod solve_expr {
|
||||
"###
|
||||
);
|
||||
}
|
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|
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#[test]
|
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fn catchall_branch_for_pattern_not_last() {
|
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infer_queries!(
|
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indoc!(
|
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r#"
|
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\x -> when x is
|
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#^
|
||||
A B _ -> ""
|
||||
A _ C -> ""
|
||||
"#
|
||||
),
|
||||
@r#"x : [A [B]* [C]*]"#
|
||||
allow_errors: true
|
||||
);
|
||||
}
|
||||
|
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#[test]
|
||||
fn catchall_branch_walk_into_nested_types() {
|
||||
infer_queries!(
|
||||
indoc!(
|
||||
r#"
|
||||
\x -> when x is
|
||||
#^
|
||||
{ a: A { b: B } } -> ""
|
||||
_ -> ""
|
||||
"#
|
||||
),
|
||||
@r#"x : { a : [A { b : [B]* }*]* }*"#
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
@ -838,26 +838,7 @@ fn unify_structure<M: MetaCollector>(
|
||||
match other {
|
||||
FlexVar(_) => {
|
||||
// If the other is flex, Structure wins!
|
||||
let outcome = merge(subs, ctx, Structure(*flat_type));
|
||||
|
||||
// And if we see a flex variable on the right hand side of a presence
|
||||
// constraint, we know we need to open up the structure we're trying to unify with.
|
||||
match (ctx.mode.is_present(), flat_type) {
|
||||
(true, FlatType::TagUnion(tags, _ext)) => {
|
||||
let new_ext = subs.fresh_unnamed_flex_var();
|
||||
let mut new_desc = ctx.first_desc;
|
||||
new_desc.content = Structure(FlatType::TagUnion(*tags, new_ext));
|
||||
subs.set(ctx.first, new_desc);
|
||||
}
|
||||
(true, FlatType::FunctionOrTagUnion(tn, sym, _ext)) => {
|
||||
let new_ext = subs.fresh_unnamed_flex_var();
|
||||
let mut new_desc = ctx.first_desc;
|
||||
new_desc.content = Structure(FlatType::FunctionOrTagUnion(*tn, *sym, new_ext));
|
||||
subs.set(ctx.first, new_desc);
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
outcome
|
||||
merge(subs, ctx, Structure(*flat_type))
|
||||
}
|
||||
FlexAbleVar(_, ability) => {
|
||||
// Structure wins
|
||||
|
||||
@ -7727,7 +7727,7 @@ All branches in an `if` must have the same type!
|
||||
|
||||
But all the previous branches match:
|
||||
|
||||
F [A]a
|
||||
F [A]
|
||||
"###
|
||||
);
|
||||
|
||||
@ -9875,4 +9875,30 @@ All branches in an `if` must have the same type!
|
||||
your code don't wonder why it is there.
|
||||
"###
|
||||
);
|
||||
|
||||
test_report!(
|
||||
flip_flop_catch_all_branches_not_exhaustive,
|
||||
indoc!(
|
||||
r#"
|
||||
\x -> when x is
|
||||
A B _ -> ""
|
||||
A _ C -> ""
|
||||
"#
|
||||
),
|
||||
@r###"
|
||||
── UNSAFE PATTERN ──────────────────────────────────────── /code/proj/Main.roc ─
|
||||
|
||||
This `when` does not cover all the possibilities:
|
||||
|
||||
4│> \x -> when x is
|
||||
5│> A B _ -> ""
|
||||
6│> A _ C -> ""
|
||||
|
||||
Other possibilities include:
|
||||
|
||||
A _ _
|
||||
|
||||
I would have to crash if I saw one of those! Add branches for them!
|
||||
"###
|
||||
);
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user