fallow_graph/graph/
public_exports.rs

1//! Exports-aware public-export-key computation (the hard 80% of 6.A).
2//!
3//! Given the set of *public-API entry points* (the `package.json` `exports`-mapped
4//! modules plus the no-`exports` source-index fallback; computed in core's
5//! `public_api_package_entry_points`, which already encodes rule R4), this
6//! resolves the set of export symbols reachable through that public surface and
7//! returns one stable `"<rel_path>::<name>"` key per public export.
8//!
9//! An export `(file, name)` is PUBLIC when its DECLARING module is part of the
10//! public surface, which is:
11//! - a public-API entry point module itself (its own exports, INCLUDING the
12//!   synthetic re-export stubs the graph materializes on a barrel for every
13//!   `export { x } from './impl'` and `export * from './impl'` it forwards), OR
14//! - a module in the `export *` closure rooted at public-API entries (a target
15//!   whose names are flattened straight into the public surface by `export *`).
16//!
17//! Keying on the surface AS EXPOSED (the entry's own name, e.g. `index.js::pub`),
18//! not the origin's internal name (`src/impl.ts::pub`), is what makes the delta
19//! exports-aware and avoids double-counting one symbol on both the barrel and
20//! the origin. A symbol re-exported only through an INTERNAL barrel that is not
21//! in `exports` never lands on a public entry or a star-target, so it produces
22//! ZERO public-API delta (the Aisha repro); one re-exported through the
23//! `exports`-mapped entry lands on that entry once (exactly one). This mirrors
24//! the exports-aware reachability the `unprovided-inject` and
25//! `unrendered-component` detectors use, kept in the graph crate so the review
26//! brief (cli) can call it directly off the retained graph.
27
28use std::path::{Path, PathBuf};
29
30use fallow_types::discover::FileId;
31use rustc_hash::FxHashSet;
32
33use super::ModuleGraph;
34
35impl ModuleGraph {
36    /// Compute the set of public-export keys reachable through the given
37    /// `public_api_entry_points` (an exports-aware set; see module docs).
38    ///
39    /// Keys are `"<root-relative forward-slashed path>::<export name>"`.
40    /// Type-only exports are skipped: a type erased at build carries no runtime
41    /// contract, so it never widens the public *value* surface that 6.A tracks.
42    #[must_use]
43    pub fn public_export_keys(
44        &self,
45        public_api_entry_points: &FxHashSet<FileId>,
46        root: &Path,
47    ) -> FxHashSet<String> {
48        let star_targets = self.public_star_re_export_targets(public_api_entry_points);
49        let mut keys: FxHashSet<String> = FxHashSet::default();
50
51        for module in &self.modules {
52            // The public surface is the exports DECLARED ON a public entry (its
53            // own + the synthetic re-export stubs the graph put there) plus the
54            // exports of any `export *` target reached from a public entry. The
55            // origin module of a NAMED re-export is internal, so its own copy of
56            // the symbol is intentionally NOT keyed (avoids double-counting and
57            // keeps an internal-barrel-only symbol out of the surface).
58            let module_is_public = public_api_entry_points.contains(&module.file_id)
59                || star_targets.contains(&module.file_id);
60            if !module_is_public {
61                continue;
62            }
63            let rel = relativize(&module.path, root);
64            for export in &module.exports {
65                if export.is_type_only {
66                    continue;
67                }
68                keys.insert(format!("{rel}::{}", export.name));
69            }
70        }
71        keys
72    }
73
74    /// The `export *` closure rooted at the public-API entry points: every module
75    /// reachable through a chain of `export * from './x'` edges starting from a
76    /// public entry. Such modules' exports are part of the public surface even
77    /// though the entry never names them.
78    fn public_star_re_export_targets(
79        &self,
80        public_api_entry_points: &FxHashSet<FileId>,
81    ) -> FxHashSet<FileId> {
82        let mut targets: FxHashSet<FileId> = public_api_entry_points
83            .iter()
84            .filter_map(|id| self.modules.get(id.0 as usize))
85            .flat_map(|module| {
86                module
87                    .re_exports
88                    .iter()
89                    .filter(|re| re.exported_name == "*")
90                    .map(|re| re.source_file)
91            })
92            .collect();
93
94        let mut stack: Vec<FileId> = targets.iter().copied().collect();
95        while let Some(id) = stack.pop() {
96            let Some(module) = self.modules.get(id.0 as usize) else {
97                continue;
98            };
99            for re in module
100                .re_exports
101                .iter()
102                .filter(|re| re.exported_name == "*")
103            {
104                if targets.insert(re.source_file) {
105                    stack.push(re.source_file);
106                }
107            }
108        }
109        targets
110    }
111}
112
113/// Strip `root` and forward-slash-normalize a module path (mirrors
114/// `impact_closure::relativize` for cross-platform key parity).
115fn relativize(path: &Path, root: &Path) -> String {
116    let rel: PathBuf = path.strip_prefix(root).unwrap_or(path).to_path_buf();
117    rel.to_string_lossy().replace('\\', "/")
118}
119
120#[cfg(test)]
121mod tests {
122    use super::*;
123    use crate::resolve::{ResolveResult, ResolvedImport, ResolvedModule, ResolvedReExport};
124    use fallow_types::discover::{DiscoveredFile, EntryPoint, EntryPointSource};
125    use fallow_types::extract::{
126        ExportInfo, ExportName, ImportInfo, ImportedName, ReExportInfo, VisibilityTag,
127    };
128    use std::path::PathBuf;
129
130    fn file(id: u32, path: &str) -> DiscoveredFile {
131        DiscoveredFile {
132            id: FileId(id),
133            path: PathBuf::from(path),
134            size_bytes: 10,
135        }
136    }
137
138    fn named_export(name: &str) -> ExportInfo {
139        ExportInfo {
140            name: ExportName::Named(name.to_string()),
141            local_name: Some(name.to_string()),
142            is_type_only: false,
143            visibility: VisibilityTag::None,
144            expected_unused_reason: None,
145            span: oxc_span::Span::new(0, 20),
146            members: vec![],
147            is_side_effect_used: false,
148            super_class: None,
149        }
150    }
151
152    fn re_export(imported: &str, exported: &str, target: FileId) -> ResolvedReExport {
153        ResolvedReExport {
154            info: ReExportInfo {
155                source: "./impl".to_string(),
156                imported_name: imported.to_string(),
157                exported_name: exported.to_string(),
158                is_type_only: false,
159                span: oxc_span::Span::new(0, 10),
160            },
161            target: ResolveResult::InternalModule(target),
162        }
163    }
164
165    fn named_import(name: &str, target: FileId) -> ResolvedImport {
166        ResolvedImport {
167            info: ImportInfo {
168                source: "./x".to_string(),
169                imported_name: ImportedName::Named(name.to_string()),
170                local_name: name.to_string(),
171                is_type_only: false,
172                from_style: false,
173                span: oxc_span::Span::new(0, 10),
174                source_span: oxc_span::Span::default(),
175            },
176            target: ResolveResult::InternalModule(target),
177        }
178    }
179
180    /// index (0, the exports entry) re-exports `pub` from impl (1, NOT public);
181    /// internal-barrel (2) re-exports `priv` from impl. consumer (3) imports both.
182    fn build_graph() -> (ModuleGraph, FxHashSet<FileId>) {
183        let files = vec![
184            file(0, "/p/index.js"),
185            file(1, "/p/src/impl.ts"),
186            file(2, "/p/src/internal.ts"),
187            file(3, "/p/src/consumer.ts"),
188        ];
189        let entry_points = vec![EntryPoint {
190            path: PathBuf::from("/p/index.js"),
191            source: EntryPointSource::PackageJsonExports,
192        }];
193        let resolved = vec![
194            ResolvedModule {
195                file_id: FileId(0),
196                path: PathBuf::from("/p/index.js"),
197                re_exports: vec![re_export("pub", "pub", FileId(1))],
198                ..Default::default()
199            },
200            ResolvedModule {
201                file_id: FileId(1),
202                path: PathBuf::from("/p/src/impl.ts"),
203                exports: vec![named_export("pub"), named_export("priv")],
204                ..Default::default()
205            },
206            ResolvedModule {
207                file_id: FileId(2),
208                path: PathBuf::from("/p/src/internal.ts"),
209                re_exports: vec![re_export("priv", "priv", FileId(1))],
210                ..Default::default()
211            },
212            ResolvedModule {
213                file_id: FileId(3),
214                path: PathBuf::from("/p/src/consumer.ts"),
215                resolved_imports: vec![
216                    named_import("pub", FileId(0)),
217                    named_import("priv", FileId(2)),
218                ],
219                ..Default::default()
220            },
221        ];
222        let graph = ModuleGraph::build(&resolved, &entry_points, &files);
223        // The exports-mapped entry set: only index.js (PackageJsonExports).
224        let public_entries: FxHashSet<FileId> = std::iter::once(FileId(0)).collect();
225        (graph, public_entries)
226    }
227
228    #[test]
229    fn export_reexported_through_exports_path_is_public() {
230        let (graph, public_entries) = build_graph();
231        let keys = graph.public_export_keys(&public_entries, Path::new("/p"));
232        // `pub` is re-exported through the exports-mapped index.js, so it appears
233        // on the public surface keyed at the entry (the exposed name), not the
234        // internal origin.
235        assert!(
236            keys.contains("index.js::pub"),
237            "exports-reachable symbol must be public: {keys:?}"
238        );
239    }
240
241    #[test]
242    fn export_reexported_only_through_internal_barrel_is_not_public() {
243        let (graph, public_entries) = build_graph();
244        let keys = graph.public_export_keys(&public_entries, Path::new("/p"));
245        // `priv` reaches a consumer ONLY through the internal (non-exports)
246        // barrel, so it is on no public-surface key (neither the entry nor a
247        // star-target).
248        assert!(
249            !keys.iter().any(|k| k.ends_with("::priv")),
250            "internal-barrel-only symbol must NOT be public: {keys:?}"
251        );
252    }
253
254    /// Build the Aisha-repro graph parameterized by which impl symbols exist and
255    /// which is re-exported through the exports-mapped `index.js`. `internal`
256    /// (if present) is re-exported only through the non-exports internal barrel.
257    fn build_aisha_graph(
258        impl_exports: &[&str],
259        exports_reexported: &[&str],
260        internal_reexported: &[&str],
261    ) -> (ModuleGraph, FxHashSet<FileId>) {
262        let files = vec![
263            file(0, "/p/index.js"),
264            file(1, "/p/src/impl.ts"),
265            file(2, "/p/src/internal.ts"),
266        ];
267        let entry_points = vec![EntryPoint {
268            path: PathBuf::from("/p/index.js"),
269            source: EntryPointSource::PackageJsonExports,
270        }];
271        let resolved = vec![
272            ResolvedModule {
273                file_id: FileId(0),
274                path: PathBuf::from("/p/index.js"),
275                re_exports: exports_reexported
276                    .iter()
277                    .map(|n| re_export(n, n, FileId(1)))
278                    .collect(),
279                ..Default::default()
280            },
281            ResolvedModule {
282                file_id: FileId(1),
283                path: PathBuf::from("/p/src/impl.ts"),
284                exports: impl_exports.iter().map(|n| named_export(n)).collect(),
285                ..Default::default()
286            },
287            ResolvedModule {
288                file_id: FileId(2),
289                path: PathBuf::from("/p/src/internal.ts"),
290                re_exports: internal_reexported
291                    .iter()
292                    .map(|n| re_export(n, n, FileId(1)))
293                    .collect(),
294                ..Default::default()
295            },
296        ];
297        let graph = ModuleGraph::build(&resolved, &entry_points, &files);
298        let public_entries: FxHashSet<FileId> = std::iter::once(FileId(0)).collect();
299        (graph, public_entries)
300    }
301
302    #[test]
303    fn done_condition_internal_zero_exports_one() {
304        let root = Path::new("/p");
305        // Base: impl exports `pub`, re-exported through the exports-mapped index.
306        let (base_graph, base_entries) = build_aisha_graph(&["pub"], &["pub"], &[]);
307        let base = base_graph.public_export_keys(&base_entries, root);
308
309        // Head A: add an internal-barrel symbol NOT in exports -> 0 public deltas.
310        let (head_a_graph, head_a_entries) =
311            build_aisha_graph(&["pub", "internalOnly"], &["pub"], &["internalOnly"]);
312        let head_a = head_a_graph.public_export_keys(&head_a_entries, root);
313        let internal_delta: Vec<_> = head_a.difference(&base).collect();
314        assert!(
315            internal_delta.is_empty(),
316            "internal-barrel symbol must yield ZERO public-API delta: {internal_delta:?}"
317        );
318
319        // Head B: add a symbol reachable through the exports path -> exactly 1.
320        let (head_b_graph, head_b_entries) =
321            build_aisha_graph(&["pub", "widget"], &["pub", "widget"], &[]);
322        let head_b = head_b_graph.public_export_keys(&head_b_entries, root);
323        let exports_delta: Vec<_> = head_b.difference(&base).collect();
324        assert_eq!(
325            exports_delta.len(),
326            1,
327            "exports-reachable symbol must yield EXACTLY ONE public-API delta: {exports_delta:?}"
328        );
329        assert_eq!(exports_delta[0], "index.js::widget");
330    }
331
332    #[test]
333    fn type_only_exports_are_skipped() {
334        let files = vec![file(0, "/p/index.ts")];
335        let entry_points = vec![EntryPoint {
336            path: PathBuf::from("/p/index.ts"),
337            source: EntryPointSource::PackageJsonExports,
338        }];
339        let mut type_export = named_export("T");
340        type_export.is_type_only = true;
341        let resolved = vec![ResolvedModule {
342            file_id: FileId(0),
343            path: PathBuf::from("/p/index.ts"),
344            exports: vec![type_export, named_export("v")],
345            ..Default::default()
346        }];
347        let graph = ModuleGraph::build(&resolved, &entry_points, &files);
348        let public_entries: FxHashSet<FileId> = std::iter::once(FileId(0)).collect();
349        let keys = graph.public_export_keys(&public_entries, Path::new("/p"));
350        assert!(keys.contains("index.ts::v"));
351        assert!(!keys.contains("index.ts::T"), "type-only export skipped");
352    }
353}
fallow_graph/graph/public_exports.rs

fallow_graph/graph/
public_exports.rs
