alef 0.84.2

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

use super::{gen_tagged_enum_binding_to_core, gen_tagged_enum_core_to_binding};
use crate::core::ir::{EnumDef, EnumVariant};

fn unit_variant(name: &str, cfg: Option<&str>) -> EnumVariant {
    EnumVariant {
        name: name.to_string(),
        cfg: cfg.map(str::to_string),
        ..Default::default()
    }
}

fn tagged_enum(rust_path: &str, variants: Vec<EnumVariant>) -> EnumDef {
    EnumDef {
        name: "VisitorResult".to_string(),
        rust_path: rust_path.to_string(),
        variants,
        serde_tag: Some("type".to_string()),
        ..Default::default()
    }
}

/// The regression this task fixes: `gen_tagged_enum_binding_to_core` and
/// `gen_tagged_enum_core_to_binding` already read `EnumVariant::cfg` and emitted a `#[cfg(...)]`
/// guard, but never checked whether the enum's `rust_path` was owned by the host crate before
/// doing so. A host-owned cfg-gated variant must keep its arm, gated, in both directions.
#[test]
fn host_owned_cfg_variant_keeps_its_arm_and_gate_in_both_directions() {
    let en = tagged_enum(
        "mylib::VisitorResult",
        vec![
            unit_variant("Continue", None),
            unit_variant("Thumbnail", Some(r#"feature = "thumbnails""#)),
        ],
    );

    let binding_to_core = gen_tagged_enum_binding_to_core(&en, "mylib", "Wasm");
    assert!(
        binding_to_core.contains("Self::Thumbnail"),
        "the host-owned variant's arm must still be emitted, got:\n{binding_to_core}"
    );
    assert_eq!(
        binding_to_core.matches("#[cfg(feature = \"thumbnails\")]").count(),
        1,
        "the host-owned variant's arm must carry its #[cfg] guard exactly once, got:\n{binding_to_core}"
    );

    let core_to_binding = gen_tagged_enum_core_to_binding(&en, "mylib", "Wasm");
    assert!(
        core_to_binding.contains("mylib::VisitorResult::Thumbnail"),
        "the host-owned variant's arm must still be emitted, got:\n{core_to_binding}"
    );
    assert_eq!(
        core_to_binding.matches("#[cfg(feature = \"thumbnails\")]").count(),
        1,
        "the host-owned variant's arm must carry its #[cfg] guard exactly once, got:\n{core_to_binding}"
    );
}

/// A variant merged in from a foreign `[[crates.source_crates]]` crate carries that crate's own
/// cfg gate. Before this fix, both functions re-emitted it verbatim regardless of ownership,
/// naming a feature this WASM crate never declares -- an `unexpected cfg condition value`
/// warning. The arm must be dropped entirely instead.
#[test]
fn foreign_owned_cfg_variant_arm_is_dropped_not_gated_in_both_directions() {
    let en = tagged_enum(
        "dep_crate::VisitorResult",
        vec![
            unit_variant("Continue", None),
            unit_variant("Testkit", Some(r#"feature = "testkit""#)),
        ],
    );

    let binding_to_core = gen_tagged_enum_binding_to_core(&en, "mylib", "Wasm");
    assert!(
        !binding_to_core.contains("#[cfg(feature = \"testkit\")]"),
        "no invalid #[cfg] naming an undeclared feature may be emitted, got:\n{binding_to_core}"
    );
    assert!(
        !binding_to_core.contains("Self::Testkit"),
        "a foreign-crate cfg-gated variant must not be referenced, got:\n{binding_to_core}"
    );

    let core_to_binding = gen_tagged_enum_core_to_binding(&en, "mylib", "Wasm");
    assert!(
        !core_to_binding.contains("#[cfg(feature = \"testkit\")]"),
        "no invalid #[cfg] naming an undeclared feature may be emitted, got:\n{core_to_binding}"
    );
    assert!(
        !core_to_binding.contains("::Testkit"),
        "a foreign-crate cfg-gated variant must not be referenced, got:\n{core_to_binding}"
    );
}

/// Negative control: an ungated enum emits no `#[cfg(...)]` at all.
#[test]
fn ungated_enum_emits_no_cfg_in_either_direction() {
    let en = tagged_enum(
        "mylib::VisitorResult",
        vec![unit_variant("Continue", None), unit_variant("Skip", None)],
    );

    let binding_to_core = gen_tagged_enum_binding_to_core(&en, "mylib", "Wasm");
    assert!(
        !binding_to_core.contains("#[cfg("),
        "ungated enum must not emit #[cfg(...)], got:\n{binding_to_core}"
    );

    let core_to_binding = gen_tagged_enum_core_to_binding(&en, "mylib", "Wasm");
    assert!(
        !core_to_binding.contains("#[cfg("),
        "ungated enum must not emit #[cfg(...)], got:\n{core_to_binding}"
    );
}

/// A cfg-gated first variant must not be chosen as the unconditional `_ =>` default in
/// `gen_tagged_enum_binding_to_core` -- the fallback must skip to the next ungated variant.
#[test]
fn default_variant_skips_a_cfg_gated_first_variant() {
    let en = tagged_enum(
        "mylib::VisitorResult",
        vec![
            unit_variant("Thumbnail", Some(r#"feature = "thumbnails""#)),
            unit_variant("Continue", None),
        ],
    );

    let binding_to_core = gen_tagged_enum_binding_to_core(&en, "mylib", "Wasm");
    assert!(
        binding_to_core.contains("_ => Self::Continue,"),
        "the unconditional default must fall back to the ungated variant, got:\n{binding_to_core}"
    );
}