Skip to content

Emitter flattens nested constructor patterns: classify_arrow_body_form's Conj arm is unreachable in emitted Rust — a silent wrong answer, not a warning #8570

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
briansrls merged 4 commits into from
Aug 19, 2026
Merged

Emitter flattens nested constructor patterns: classify_arrow_body_form's Conj arm is unreachable in emitted Rust — a silent wrong answer, not a warning #8570

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
5475617
WIP: RC-aware pattern emission guard (held, pre-sync)
Aug 19, 2026
c9a1297
Merge remote-tracking branch 'origin/main' into session/clever-owl-561
Aug 19, 2026
c1ce5bc
Regenerate stage0: v1_compiler_emit_rust.rs for RC-aware pattern guar…
Aug 19, 2026
df99b2f
Merge remote-tracking branch 'origin/main' into session/clever-owl-561
Aug 19, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
125 changes: 83 additions & 42 deletions src/v1/05_emit_rust.dag
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6507,6 +6507,16 @@ fn variant_pattern_shape_key(rust_name: String, resolved_parent: String?) -> Str
}
}

fn variant_pattern_shape_str(qualified: String, rust_name: String, resolved_parent: String?, emit_info: EmitGraphInfo) -> String {
let shape_key = variant_pattern_shape_key(rust_name: rust_name, resolved_parent: resolved_parent)
let is_positional = set_contains(emit_info.positional_payload_variants, shape_key)
|| set_contains(emit_info.positional_payload_variants, qualified)
let is_fielded = set_contains(emit_info.fielded_variants, shape_key)
|| set_contains(emit_info.fielded_variants, qualified)
if is_positional { concat(qualified, "(_)") }
else if is_fielded { concat(qualified, " { .. }") } else { qualified }
}

fn emit_variant_pattern(name: String, parent_enum: String?, field_bindings: List<Node>, path_prefix: List<String>, shared_types: Set<String>, scrut_type: String, source_indices: Map<String, NewlineIndex>, emit_info: EmitGraphInfo) -> String {
let bare_name = qualified_last_segment(name: name)
let resolved_parent = pattern_parent_enum(name: bare_name, parent_enum: parent_enum, scrut_type: scrut_type, type_summaries: emit_info.type_summaries)
Expand Down Expand Up @@ -6560,25 +6570,13 @@ fn emit_variant_pattern(name: String, parent_enum: String?, field_bindings: List
Absent => qualified
}
} else if field_bindings |> count == 0 {
let shape_key = variant_pattern_shape_key(rust_name: rust_name, resolved_parent: resolved_parent)
let is_positional = set_contains(emit_info.positional_payload_variants, shape_key)
|| set_contains(emit_info.positional_payload_variants, qualified)
let is_fielded = set_contains(emit_info.fielded_variants, shape_key)
|| set_contains(emit_info.fielded_variants, qualified)
if is_positional { concat(qualified, "(_)") }
else if is_fielded { concat(qualified, " { .. }") } else { qualified }
variant_pattern_shape_str(qualified: qualified, rust_name: rust_name, resolved_parent: resolved_parent, emit_info: emit_info)
} else {
let effective_bindings = field_bindings |> filter(fb =>
match field_binding_pattern(n: fb) { Wildcard => false _ => true }
)
if effective_bindings |> count == 0 {
let shape_key2 = variant_pattern_shape_key(rust_name: rust_name, resolved_parent: resolved_parent)
let is_positional2 = set_contains(emit_info.positional_payload_variants, shape_key2)
|| set_contains(emit_info.positional_payload_variants, qualified)
let is_fielded2 = set_contains(emit_info.fielded_variants, shape_key2)
|| set_contains(emit_info.fielded_variants, qualified)
if is_positional2 { concat(qualified, "(_)") }
else if is_fielded2 { concat(qualified, " { .. }") } else { qualified }
variant_pattern_shape_str(qualified: qualified, rust_name: rust_name, resolved_parent: resolved_parent, emit_info: emit_info)
} else {
let binding_strs = effective_bindings |> map(fb =>
let fb_name = field_binding_name_at(n: fb, source_indices: source_indices)
Expand Down Expand Up @@ -6822,25 +6820,13 @@ fn emit_variant_pattern_rc_aware(name: String, parent_enum: String?, field_bindi
Absent => qualified
}
} else if field_bindings |> count == 0 {
let shape_key = variant_pattern_shape_key(rust_name: rust_name, resolved_parent: resolved_parent)
let is_positional = set_contains(emit_info.positional_payload_variants, shape_key)
|| set_contains(emit_info.positional_payload_variants, qualified)
let is_fielded = set_contains(emit_info.fielded_variants, shape_key)
|| set_contains(emit_info.fielded_variants, qualified)
if is_positional { concat(qualified, "(_)") }
else if is_fielded { concat(qualified, " { .. }") } else { qualified }
variant_pattern_shape_str(qualified: qualified, rust_name: rust_name, resolved_parent: resolved_parent, emit_info: emit_info)
} else {
let effective_bindings = field_bindings |> filter(fb =>
match field_binding_pattern(n: fb) { Wildcard => false _ => true }
)
if effective_bindings |> count == 0 {
let shape_key2 = variant_pattern_shape_key(rust_name: rust_name, resolved_parent: resolved_parent)
let is_positional2 = set_contains(emit_info.positional_payload_variants, shape_key2)
|| set_contains(emit_info.positional_payload_variants, qualified)
let is_fielded2 = set_contains(emit_info.fielded_variants, shape_key2)
|| set_contains(emit_info.fielded_variants, qualified)
if is_positional2 { concat(qualified, "(_)") }
else if is_fielded2 { concat(qualified, " { .. }") } else { qualified }
variant_pattern_shape_str(qualified: qualified, rust_name: rust_name, resolved_parent: resolved_parent, emit_info: emit_info)
} else {
let binding_strs = effective_bindings |> map(fb =>
let fb_name = field_binding_name_at(n: fb, source_indices: source_indices)
Expand Down Expand Up @@ -6886,6 +6872,65 @@ fn match_pattern_is_irrefutable(pattern: MatchPattern) -> Bool {
}
}

fn variant_pattern_shape_for(name: String, parent_enum: String?, scrut_type: String, emit_info: EmitGraphInfo) -> String {
let bare_name = qualified_last_segment(name: name)
let resolved_parent = pattern_parent_enum(name: bare_name, parent_enum: parent_enum, scrut_type: scrut_type, type_summaries: emit_info.type_summaries)
let optional_variant = is_optional_variant_name(name: bare_name)
&& (is_optional_parent(parent_enum: resolved_parent) || resolved_parent == none)
let rust_name = if optional_variant {
if is_some_like_variant_name(name: bare_name) { "Some" } else { "None" }
} else { bare_name }
let qualified = if optional_variant {
rust_name
} else {
variant_pattern_qualified_path(rust_name: rust_name, resolved_parent: resolved_parent)
}
variant_pattern_shape_str(qualified: qualified, rust_name: rust_name, resolved_parent: resolved_parent, emit_info: emit_info)
}

fn collect_pattern_rc_variant_guards(pattern: MatchPattern, rc_analysis: RcPatternAnalysis, shared_types: Set<String>, source_indices: Map<String, NewlineIndex>, emit_info: EmitGraphInfo) -> String {
match pattern {
VariantPattern { name: n, parent_enum: parent_enum, field_bindings: fbs } =>
let bare_n = qualified_last_segment(name: n)
if is_optional_variant_name(name: bare_n) && is_optional_parent(parent_enum: parent_enum) {
if fbs |> count == 1 {
match fbs |> first {
Present { value: fb } =>
let fb_pat = field_binding_pattern(n: fb)
let inner_analysis = analyze_rc_pattern(pattern: fb_pat, scrut_type: "", shared_types: shared_types, emit_info: emit_info, source_indices: source_indices)
collect_pattern_rc_variant_guards(pattern: fb_pat, rc_analysis: inner_analysis, shared_types: shared_types, source_indices: source_indices, emit_info: emit_info)
Absent => ""
}
} else { "" }
} else {
let resolved_parent = pattern_parent_enum(name: bare_n, parent_enum: parent_enum, scrut_type: "", type_summaries: emit_info.type_summaries)
let parts = fbs |> flat_map(fb =>
let fb_name = field_binding_name_at(n: fb, source_indices: source_indices)
if fb_name == "0" {
let fb_pat = field_binding_pattern(n: fb)
let payload_scrut = positional_payload_scrut_type(parent_enum: resolved_parent, variant_name: bare_n, field_binding: fb, emit_info: emit_info, source_indices: source_indices)
let inner_analysis = analyze_rc_pattern(pattern: fb_pat, scrut_type: payload_scrut, shared_types: shared_types, emit_info: emit_info, source_indices: source_indices)
let inner = collect_pattern_rc_variant_guards(pattern: fb_pat, rc_analysis: inner_analysis, shared_types: shared_types, source_indices: source_indices, emit_info: emit_info)
if inner == "" { [] } else { [inner] }
} else if field_needs_rc_ref(field_name: fb_name, rc_analysis: rc_analysis) {
let fb_pat = field_binding_pattern(n: fb)
if match_pattern_is_irrefutable(pattern: fb_pat) { [] }
else {
match fb_pat {
VariantPattern { name: inner_n, parent_enum: inner_parent, field_bindings: _ } =>
let shape = variant_pattern_shape_for(name: inner_n, parent_enum: inner_parent, scrut_type: "", emit_info: emit_info)
[concat("matches!(", emit_ident(name: fb_name, target: Rust), ".as_ref(), ", shape, ")")]
_ => []
}
}
} else { [] }
)
parts |> join(separator: " && ")
}
_ => ""
}
}

fn rc_pattern_preludes(pattern: MatchPattern, rc_analysis: RcPatternAnalysis, shared_types: Set<String>, source_indices: Map<String, NewlineIndex>, emit_info: EmitGraphInfo) -> String {
match pattern {
VariantPattern { name: n, parent_enum: parent_enum, field_bindings: fbs } =>
Expand Down Expand Up @@ -8773,17 +8818,15 @@ fn emit_typed_match_arm(arm: Node, registry: Map<String, ItemInfo>, scope: Infer
emit_pattern(pattern: arm_pat, path_prefix: [], shared_types: shared_types, scrut_type: scrut_type, source_indices: si, emit_info: emit_info)
}
let field_guards = collect_pattern_string_guards(pattern: arm_pat, path_prefix: [], source_indices: si)
let rc_variant_guards = if rc_analysis.needs_rc_pattern {
collect_pattern_rc_variant_guards(pattern: arm_pat, rc_analysis: rc_analysis, shared_types: shared_types, source_indices: si, emit_info: emit_info)
} else { "" }
let arm_guard_str = match arm_g {
Present { value: g } => emit_typed_expr(texpr: g, registry: registry, scope: scope, depth: depth, shared_types: shared_types, emit_info: emit_info, fuel: 1024)
Absent => ""
}
let guard_str = if field_guards != "" && arm_guard_str != "" {
concat(" if ", field_guards, " && ", arm_guard_str)
} else if field_guards != "" {
concat(" if ", field_guards)
} else if arm_guard_str != "" {
concat(" if ", arm_guard_str)
} else { "" }
let guard_parts = [field_guards, rc_variant_guards, arm_guard_str] |> filter(g => g != "")
let guard_str = if guard_parts |> count == 0 { "" } else { concat(" if ", guard_parts |> join(separator: " && ")) }
let body_str = match arm_b.expr_data {
ExprVar { binding_kind: body_binding_kind } =>
let body_name = expr_var_name_at(texpr: arm_b, source_indices: si)
Expand Down Expand Up @@ -9676,17 +9719,15 @@ fn emit_typed_tco_match_arm(arm: Node, fn_name: String, params: List<Node>, regi
emit_pattern(pattern: arm_pat, path_prefix: [], shared_types: shared_types, scrut_type: scrut_type, source_indices: si, emit_info: emit_info)
}
let field_guards = collect_pattern_string_guards(pattern: arm_pat, path_prefix: [], source_indices: si)
let rc_variant_guards = if rc_analysis.needs_rc_pattern {
collect_pattern_rc_variant_guards(pattern: arm_pat, rc_analysis: rc_analysis, shared_types: shared_types, source_indices: si, emit_info: emit_info)
} else { "" }
let arm_guard_str = match arm_g {
Present { value: g } => emit_typed_expr(texpr: g, registry: registry, scope: scope, depth: depth, shared_types: shared_types, emit_info: emit_info, fuel: 1024)
Absent => ""
}
let guard_str = if field_guards != "" && arm_guard_str != "" {
concat(" if ", field_guards, " && ", arm_guard_str)
} else if field_guards != "" {
concat(" if ", field_guards)
} else if arm_guard_str != "" {
concat(" if ", arm_guard_str)
} else { "" }
let guard_parts = [field_guards, rc_variant_guards, arm_guard_str] |> filter(g => g != "")
let guard_str = if guard_parts |> count == 0 { "" } else { concat(" if ", guard_parts |> join(separator: " && ")) }
let body_str = emit_typed_tco_expr(texpr: arm_b, fn_name: fn_name, params: params, registry: registry, scope: scope, depth: depth, shared_types: shared_types, emit_info: emit_info)
if rc_analysis.needs_rc_pattern {
let prelude = rc_pattern_preludes(pattern: arm_pat, rc_analysis: rc_analysis, shared_types: shared_types, source_indices: si, emit_info: emit_info)
Expand Down
Loading