alef 0.103.2

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

//! Regression coverage for alef-issue #451: a cfg-gated top-level function removed its feature
//! from the PHP crate's `[features]` table even when a struct field gated on the SAME feature
//! still needed it declared.
//!
//! Mechanism: `php_declared_features` (`scaffold/languages/php.rs`) started every feature name
//! any cfg gate in the surface referenced, then unconditionally removed every name a top-level
//! function's cfg referenced (`php_function_referenced_feature_names`) -- correct in isolation,
//! because PHP never gates a function by cfg (it is always emitted into the facade; see
//! `rust_bindings.rs::generate_bindings`'s doc comment). But when a struct field's cfg named that
//! same feature, the field's gate is copied onto the generated `From` impl
//! (`ConversionConfig::restrict_field_gate`) and narrowed against that same declared set. With the
//! feature stripped, `restrict_cfg_gate_to_declared` found nothing declared for it
//! (`DeclaredCfgGate::Unreachable`) and fell back to re-emitting the original, now-undeclared
//! gate -- `unexpected_cfg_condition_value` under `-D warnings`, and once rustc evaluated the gate
//! false, a struct literal missing the field (E0063), because the binding struct declares the
//! field unconditionally (it is a trait-bridge "never skip" field here, same as the real report).
//!
//! Fixture names are neutral (`alpha`, `Config`, `alpha_reader`) -- the real report used a
//! consumer's actual crate/feature/function names, which must not appear in alef's own fixtures.

use super::PhpBackend;
use crate::core::backend::Backend;
use crate::core::config::{NewAlefConfig, ResolvedCrateConfig};
use crate::core::ir::{ApiSurface, FieldDef, FunctionDef, TypeDef, TypeRef};

const FEATURE: &str = "alpha";

fn php_config_with_feature(feature: &str) -> ResolvedCrateConfig {
    let toml_src = format!(
        "[workspace]\nlanguages = [\"php\"]\n[[crates]]\nname = \"test-lib\"\nsources = [\"src/lib.rs\"]\n\
         [crates.php]\nfeatures = [\"{feature}\"]\n"
    );
    let cfg: NewAlefConfig = toml::from_str(&toml_src).expect("valid config");
    cfg.resolve().expect("resolve config").remove(0)
}

/// A HOST-owned, non-defaultable struct with a field gated on `FEATURE`, plus a top-level
/// function ALSO gated on `FEATURE` -- the exact shape from the report: the field needs `FEATURE`
/// declared for its copied `#[cfg(...)]` gate to compile, while the function's own cfg is a
/// reason `php_function_referenced_feature_names` wants to strip that same name.
fn shared_feature_api() -> ApiSurface {
    ApiSurface {
        crate_name: "test-lib".to_string(),
        version: "0.1.0".to_string(),
        types: vec![TypeDef {
            name: "Config".to_string(),
            rust_path: "test_lib::Config".to_string(),
            fields: vec![
                FieldDef {
                    name: "always_on".to_string(),
                    ty: TypeRef::Primitive(crate::core::ir::PrimitiveType::Bool),
                    ..Default::default()
                },
                FieldDef {
                    name: "alpha_option".to_string(),
                    ty: TypeRef::String,
                    cfg: Some(format!(r#"feature = "{FEATURE}""#)),
                    ..Default::default()
                },
            ],
            ..Default::default()
        }],
        functions: vec![FunctionDef {
            name: "alpha_reader".to_string(),
            rust_path: "test_lib::alpha_reader".to_string(),
            return_type: TypeRef::Primitive(crate::core::ir::PrimitiveType::Bool),
            cfg: Some(format!(r#"feature = "{FEATURE}""#)),
            ..Default::default()
        }],
        ..Default::default()
    }
}

fn cargo_toml_content(files: &[crate::core::backend::GeneratedFile]) -> &str {
    &files
        .iter()
        .find(|f| f.path.to_string_lossy().ends_with("Cargo.toml"))
        .expect("scaffold_php_cargo must emit Cargo.toml")
        .content
}

fn lib_rs_content(files: &[crate::core::backend::GeneratedFile]) -> &str {
    &files
        .iter()
        .find(|f| f.path.to_string_lossy().ends_with("lib.rs"))
        .expect("generate_bindings must emit lib.rs")
        .content
}

/// Isolated unit coverage: `php_declared_features` must keep a name referenced by BOTH a
/// function and a field, and must still drop a name referenced ONLY by a function.
#[test]
fn php_declared_features_keeps_a_name_a_field_still_needs() {
    let api = shared_feature_api();
    let declared = crate::scaffold::languages::php::php_declared_features(&api, &[]);
    assert!(
        declared.contains(FEATURE),
        "a feature name a struct field's cfg references must stay declared even when a \
         top-level function also references it; got {declared:?}"
    );
}

/// Regression guard for the OTHER direction: a feature referenced only by a function (no field,
/// variant, or type anywhere references it) must still be removed from the declared set -- this
/// backend must not regress into declaring every function-referenced feature unconditionally.
#[test]
fn php_declared_features_still_drops_a_function_only_name() {
    let mut api = shared_feature_api();
    api.types.clear();
    let declared = crate::scaffold::languages::php::php_declared_features(&api, &[]);
    assert!(
        !declared.contains(FEATURE),
        "a feature referenced only by a top-level function's cfg (no field/type anywhere \
         references it) must stay out of the declared set; got {declared:?}"
    );
}

/// End-to-end: the invariant the whole mechanism must uphold. If the generated `From` impl
/// carries a `#[cfg(feature = "X")]` gate on a field, "X" must appear in the same crate's
/// generated `[features]` table -- otherwise the gate names an undeclared feature and rustc
/// evaluates it false, dropping the field from the struct literal it is required to fully
/// initialize (E0063), exactly the failure alef-issue #451 reports.
#[test]
fn generated_field_cfg_gate_names_a_feature_declared_in_the_same_crate() {
    let api = shared_feature_api();
    let config = php_config_with_feature(FEATURE);

    let cargo_files =
        crate::scaffold::languages::php::scaffold_php_cargo(&api, &config).expect("scaffold_php_cargo ok");
    let cargo_toml = cargo_toml_content(&cargo_files);

    let bindings = PhpBackend
        .generate_bindings(&api, &config)
        .expect("generate_bindings ok");
    let lib_rs = lib_rs_content(&bindings);

    let expected_gate = format!(r#"#[cfg(feature = "{FEATURE}")]"#);
    assert!(
        lib_rs.contains(&expected_gate),
        "expected the field conversion to still carry its cfg gate:\n{lib_rs}"
    );

    let declared_line = format!(r#"{FEATURE} = ["test-lib/{FEATURE}"]"#);
    assert!(
        cargo_toml.contains(&declared_line),
        "a struct field's cfg gate named `{FEATURE}` in the generated conversion, so the PHP \
         crate's own [features] table must declare it (`{declared_line}`); got:\n{cargo_toml}"
    );

    let default_line = cargo_toml
        .lines()
        .find(|line| line.starts_with("default = ["))
        .expect("default array present");
    assert!(
        default_line.contains(FEATURE),
        "`{FEATURE}` is configured for this binding, so it must also be enabled by default; \
         got: {default_line}"
    );
}