alef 0.83.1

Opinionated polyglot binding generator for Rust libraries
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219

//! Regression coverage for the extraction gap that blocked regenerating a consumer repo whose
//! source looked like:
//!
//! ```rust,ignore
//! #[derive(Debug, Clone, Default, Serialize, Deserialize)]
//! pub struct OcrElement {
//!     pub geometry: OcrBoundingGeometry,   // named type, required
//!     pub confidence: OcrConfidence,       // named type, required
//!     #[serde(default = "default_page_number")]
//!     pub page_number: u32,
//! }
//!
//! fn default_page_number() -> u32 { 1 }
//! ```
//!
//! `helpers::fields::extract_field` recorded `page_number`'s default as
//! `DefaultValue::FunctionCall("default_page_number")` unconditionally. Generation then tried to
//! recover the real value through `rust_default_via_source_deserialize` — deserializing an
//! empty-field JSON stub through `OcrElement`'s own `Deserialize` impl — which requires a JSON
//! placeholder for every other required sibling field; `json_placeholder_literal` has no
//! placeholder for a `TypeRef::Named` field, so the two required named-type siblings
//! (`geometry`, `confidence`) made that recovery impossible, and generation failed closed with
//! "cannot preserve 1 serde default function(s)". The real value was readable all along, one
//! level up: `default_page_number`'s own body is the literal `1`.
use super::*;
use crate::codegen::config_gen::validate_rust_default_functions;
use crate::core::ir::DefaultValue;

/// The exact reported shape, reduced to the minimum that reproduces the failure: two required
/// named-type sibling fields (so `rust_default_via_source_deserialize` cannot build a probe) plus
/// one `#[serde(default = "path")]` field naming a private, free, literal-returning function.
const OCR_ELEMENT_SOURCE: &str = r#"
    #[derive(Debug, Clone, Default, Serialize, Deserialize)]
    pub struct OcrElement {
        pub geometry: OcrBoundingGeometry,
        pub confidence: OcrConfidence,
        #[serde(default = "default_page_number")]
        pub page_number: u32,
    }

    #[derive(Debug, Clone, Default, Serialize, Deserialize)]
    pub struct OcrBoundingGeometry {
        pub x: f64,
    }

    #[derive(Debug, Clone, Default, Serialize, Deserialize)]
    pub struct OcrConfidence {
        pub value: f64,
    }

    fn default_page_number() -> u32 {
        1
    }
"#;

#[test]
fn private_free_function_default_folds_to_its_literal_value() {
    let surface = extract_from_source(OCR_ELEMENT_SOURCE);
    let element = surface
        .types
        .iter()
        .find(|typ| typ.name == "OcrElement")
        .expect("OcrElement must be extracted");
    let page_number = element
        .fields
        .iter()
        .find(|field| field.name == "page_number")
        .expect("page_number field must be extracted");

    assert_eq!(
        page_number.typed_default,
        Some(DefaultValue::IntLiteral(1)),
        "default_page_number()'s body is the literal `1`; alef must read it instead of leaving \
         an unresolvable FunctionCall"
    );
}

/// The end-to-end proof: `validate_rust_default_functions` is exactly the check that made
/// generation fail with "cannot preserve 1 serde default function(s)". Once the field's default
/// is folded to a literal, that check has nothing left to refuse.
#[test]
fn ocr_element_shape_passes_rust_default_function_validation() {
    let surface = extract_from_source(OCR_ELEMENT_SOURCE);
    validate_rust_default_functions(&surface).expect(
        "a foldable #[serde(default = \"path\")] default must not require the source-deserialize \
         recovery at all, so two required named-type siblings must not block it",
    );
}

/// Control: a path-qualified associated function (`Settings::default_retry_limit`) must fold
/// exactly like a bare free function — the task's second required shape.
#[test]
fn path_qualified_associated_function_default_folds_to_its_literal_value() {
    let source = r#"
        pub struct Settings;

        impl Settings {
            fn default_retry_limit() -> u32 {
                3
            }
        }

        #[derive(Debug, Clone, Default, Serialize, Deserialize)]
        pub struct Policy {
            #[serde(default = "Settings::default_retry_limit")]
            pub retry_limit: u32,
        }
    "#;

    let surface = extract_from_source(source);
    let policy = surface.types.iter().find(|typ| typ.name == "Policy").unwrap();
    let retry_limit = policy.fields.iter().find(|field| field.name == "retry_limit").unwrap();

    assert_eq!(retry_limit.typed_default, Some(DefaultValue::IntLiteral(3)));
}

/// Control: a genuinely unfoldable `#[serde(default = "path")]` function (one whose value alef
/// cannot prove statically) must keep failing generation exactly as before, when it also has a
/// required named-type sibling that blocks the `rust_default_via_source_deserialize` recovery —
/// the same blocker that made the original `OcrElement` case fail. Folding must never become a
/// way to silence `validate_rust_default_functions` for a value alef cannot actually prove.
#[test]
fn genuinely_unfoldable_function_default_still_fails_validation() {
    let source = r#"
        #[derive(Debug, Clone, Default, Serialize, Deserialize)]
        pub struct Cache {
            pub warmup: WarmupPolicy,
            #[serde(default = "computed_default")]
            pub warm_entries: u32,
        }

        #[derive(Debug, Clone, Default, Serialize, Deserialize)]
        pub struct WarmupPolicy {
            pub eager: bool,
        }

        fn computed_default() -> u32 {
            let base = read_warm_entry_count_from_disk();
            base
        }
    "#;

    let surface = extract_from_source(source);
    let cache = surface.types.iter().find(|typ| typ.name == "Cache").unwrap();
    let warm_entries = cache.fields.iter().find(|field| field.name == "warm_entries").unwrap();

    assert_eq!(
        warm_entries.typed_default,
        Some(DefaultValue::FunctionCall("computed_default".to_string())),
        "a multi-statement, non-foldable body must stay FunctionCall, not be guessed at"
    );

    let error = validate_rust_default_functions(&surface).expect_err(
        "a genuinely unfoldable serde default function, blocked from the source-deserialize \
         recovery by a required named-type sibling, must still fail generation rather than \
         silently ship a guessed value",
    );
    assert!(
        error.to_string().contains("computed_default"),
        "the failure must still name the unreadable function: {error}"
    );
}

/// Resolution must commit to the function the path actually names. `Settings::default_retry`
/// names the associated function; if that body cannot be folded, the answer is "not readable",
/// not "read whatever free function happens to share the last segment". A same-module free
/// `default_retry` is a different function with a different value, and silently substituting it
/// is the read-the-wrong-artifact failure this pass must not commit — the value would look
/// exactly as authoritative as one alef genuinely read.
#[test]
fn an_unfoldable_associated_function_never_falls_back_to_a_same_named_free_function() {
    let source = r#"
        #[derive(Debug, Clone, Default, Serialize, Deserialize)]
        pub struct Settings {
            pub name: Label,
            #[serde(default = "Settings::default_retry")]
            pub retry: u32,
        }

        #[derive(Debug, Clone, Default, Serialize, Deserialize)]
        pub struct Label {
            pub text: String,
        }

        impl Settings {
            pub fn default_retry() -> u32 {
                let base = read_retry_from_env();
                base
            }
        }

        fn default_retry() -> u32 {
            99
        }
    "#;

    let surface = extract_from_source(source);
    let settings = surface.types.iter().find(|typ| typ.name == "Settings").unwrap();
    let retry = settings.fields.iter().find(|field| field.name == "retry").unwrap();

    // Not `IntLiteral(99)`: that is the free function's value, and reading it here would be the
    // whole defect. The fold declines, and `postprocess::resolve_public_default_functions` then
    // upgrades the still-unfolded path to `PublicFunctionCall` because the associated function is
    // `pub` — a real, callable answer for the Rust-emitting backends, and honestly "not folded"
    // for every other one.
    assert_eq!(
        retry.typed_default,
        Some(DefaultValue::PublicFunctionCall(
            "test_crate::Settings::default_retry".to_string()
        )),
        "the path names the associated function; when its body is unfoldable the value stays \
         unread, and the unrelated free `default_retry` (99) must never stand in for it"
    );
    assert_ne!(
        retry.typed_default,
        Some(DefaultValue::IntLiteral(99)),
        "the same-named free function's value must never be substituted for the associated one"
    );
}