Stdlib module compiler/frontend/diagnostics.vit

Overview

`compiler/frontend/diagnostics.vit` is a compiler-facing or orchestrator module inside the `compiler` family. It should be read as one focused slice of the broader family responsibility: Compiler-owned stdlib surfaces that support self-hosted compiler and driver integration.

Purpose

This file should be chosen because of responsibility, not because its name “sounds close enough”. Inside the compiler family, it carries one focused part of the contract and keeps that responsibility separate from neighboring concerns.

• A self-hosted compiler flow can reuse structured helpers without pretending they are general stdlib entry points.
• A driver surface can depend on this family while still keeping its public contract documented elsewhere.

Taxonomy

Think of this page as a generated encyclopedia entry rather than a hand-written tutorial. The goal is to show what kind of module this is, how dense it is, and what reading strategy makes sense before depending on it.

• Medium procedure surface: this file groups several related operations behind one namespace.
• Owns domain vocabulary: the module declares data shapes in addition to executable helpers, so its types are part of the contract.
• Minimal top-level dependencies: the module reads as mostly self-contained from its opening declarations.
• Explicit export surface: the file ends with visible export declarations instead of relying only on implicit namespace discovery.

Implementation profile

This profile is inferred directly from the source text. It does not replace reading the file, but it tells you quickly whether the module is mostly declarative, loop-heavy, branch-heavy, or organized around many small exits.

Top-level API inventory

Imported surfaces

This file does not advertise a top-level `use` surface in its opening declarations. That often means it is either self-contained or an aggregation layer.

Position in family

This file is module 19 of 27 in the compiler family when ordered by path. By procedure count it ranks 6, and by line count it ranks 1. Those ranks are useful as rough signals of breadth, not as quality judgments.

Declaration map

The declaration map turns raw source into a scan-friendly catalog. It is useful when the file is large enough that a reader wants to orient by kinds of surfaces first.

The table is exhaustive for top-level declarations of the selected kinds. This file declares 14 matching surfaces.

Representative signatures

These signatures are shown in source order so the page keeps the feel of a reference manual, not just a keyword cloud.

• pick DiagnosticLevel { (line 3)
• form DiagnosticSpan { (line 12)
• form Diagnostic { (line 20)
• form DiagnosticBag { (line 30)
• proc span_at(line: int, column: int) -> DiagnosticSpan { (line 39)
• proc new_bag() -> DiagnosticBag { (line 49)
• proc add(bag: DiagnosticBag, level: DiagnosticLevel, code: string, message: string, line: int, column: int) -> DiagnosticBag { (line 60)
• proc add_error(bag: DiagnosticBag, code: string, message: string, line: int, column: int) -> DiagnosticBag { (line 88)
• proc add_warning(bag: DiagnosticBag, code: string, message: string, line: int, column: int) -> DiagnosticBag { (line 92)
• proc add_note(bag: DiagnosticBag, code: string, message: string, line: int, column: int) -> DiagnosticBag { (line 96)
• proc attach_note(bag: DiagnosticBag, note: string) -> DiagnosticBag { (line 100)
• proc attach_help(bag: DiagnosticBag, help: string) -> DiagnosticBag { (line 110)
• proc has_errors(bag: DiagnosticBag) -> bool { (line 120)

How to use this module

Start by reading the file as an ownership boundary. Ask three questions: what enters this module, what stable types or procedures it exports, and what adjacent module should stay outside of it.

1. Read space and top-level imports first so the ownership boundary of compiler/frontend/diagnostics.vit is explicit.
2. Read declared forms and picks before algorithms so the data vocabulary is stable in your head.
3. Traverse procedures in source order; the early helpers usually explain the naming and numeric conventions used later.
4. Only after that compare neighbor modules, because the right boundary choice matters more than memorizing one helper name.

User example

This example is generated from the actual stdlib module surface. Its job is not to be the smallest snippet possible; its job is to show a realistic consumer-shaped file that exercises the module and mirrors the language keywords the module itself relies on.

space demo/compiler_frontend_diagnostics
form UserReport {
  label: string,
  ready: bool
}
pick UserOutcome {
  case Ready(message: string)
  case Empty(reason: string)
}
proc run_example() -> UserOutcome {
  let result = span_at(1, 1)
  let ready: bool = has_errors(DiagnosticBag())
  let stable: bool = ready and true
  let fallback: bool = ready or false
  let retries: int = 0
  set retries = retries + 1
  if ready {
    give UserOutcome.Empty("module not ready")
  } else {
    give UserOutcome.Ready("ok")
  }
}
export run_example

Keyword coverage

This table makes the “all keywords of the module” requirement auditable. It compares the detected Vitte keywords in the source file with the generated consumer example above.

The generated snippet exercises every detected Vitte keyword used by this module.

Source shape

space vitte/compiler/frontend/diagnostics
pick DiagnosticLevel {
  Info,
  Error,
  Warning,
  Note,
  Help,
  Fatal
}
form DiagnosticSpan {

The excerpt is not meant to replace the file. It exists to make the module recognizable at first glance, the same way a Wikipedia infobox helps the reader orient before reading the whole article.

Source landmarks

Large files are easier to retain when they have visible landmarks. When the source contains explicit section banners, they are surfaced here; otherwise the first major declarations are used as anchors.

• Line 1: space vitte/compiler/frontend/diagnostics
• Line 3: pick DiagnosticLevel {
• Line 12: form DiagnosticSpan {
• Line 20: form Diagnostic {
• Line 30: form DiagnosticBag {
• Line 39: proc span_at(line: int, column: int) -> DiagnosticSpan {
• Line 49: proc new_bag() -> DiagnosticBag {
• Line 60: proc add(bag: DiagnosticBag, level: DiagnosticLevel, code: string, message: string, line: int, column: int) -> DiagnosticBag {

Source organization

When a file carries its own internal chaptering, those chapters usually reveal the intended reading order better than a flat symbol list. This section reconstructs that organization from the source itself.

Complete API catalog

This catalog is the exhaustive file-level index for the module. It is intentionally closer to a generated encyclopedia appendix than to a tutorial summary.

Data surfaces

Procedures

Exports

Integration boundaries

Within compiler, this file should remain focused. If a future helper changes the host boundary, scheduling boundary, or data-shape boundary, it probably belongs in a neighbor module instead of being added here by convenience.

• Family responsibility: Compiler-owned stdlib surfaces that support self-hosted compiler and driver integration.
• Family architecture role: This family is not general-purpose business code. It exists to support compiler-owned flows where the compiler and stdlib need a shared contract.

Composition guidance

Choose this module when

• Choose compiler/frontend/diagnostics.vit when the main question is owned by this module rather than by transport, storage, orchestration, or user-interface code.
• A self-hosted compiler flow can reuse structured helpers without pretending they are general stdlib entry points.
• A driver surface can depend on this family while still keeping its public contract documented elsewhere.

Pause before extending it when

• Avoid extending this file when the new helper mostly changes the boundary to host I/O, runtime coordination, or foreign integration instead of staying inside compiler.
• Check nearby modules such as compiler/backends/ast/target_decl.vit, compiler/backends/ast/target_expr.vit, compiler/backends/ast/target_stmt.vit before adding convenience wrappers here.

Relationship table

This table keeps the page closer to a real encyclopedia entry: a module is easier to understand when compared with its nearest alternatives in the same family.

Neighbor modules

• compiler/backends/ast/target_decl.vit
• compiler/backends/ast/target_expr.vit
• compiler/backends/ast/target_stmt.vit
• compiler/backends/ast/target_type.vit
• compiler/backends/backend.vit
• compiler/backends/context/backend_context.vit
• compiler/backends/emit/emit.vit
• compiler/backends/lower/lower_mir.vit