alef 0.84.1

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

//! Regression coverage for the generated wasm crate's `[features] default = [...]` switching a
//! core-crate feature back on that its own core dependency line had just switched off.
//!
//! `gen_cargo_toml` writes two things that must agree about the same core crate:
//!
//! 1. the dependency line, `default-features = false, features = [...]` whenever
//!    `features_for_language(Language::Wasm)` is non-empty, and
//! 2. the `[features]` table, whose `default = [...]` row is the intersection of the
//!    cfg-referenced feature names with `codegen::cfg::enabled_features_for_language`.
//!
//! `enabled_features_for_language` unions in the core crate's own declared `default = [...]` when
//! `core_default_features_active` says the dependency edge keeps them -- and that predicate used
//! to answer `true` for every language but R, wasm included. So a core crate declaring
//! `default = ["native-http"]` produced `default = ["native-http", ...]` in the wasm manifest,
//! whose forwarding row `native-http = ["<core>/native-http"]` re-enabled the exact feature the
//! dependency line had turned off. In a downstream consumer that feature pulls in reqwest and
//! tokio's native I/O stack, and the wasm32 build died on `This wasm target is unsupported by
//! mio. If using Tokio, disable the net feature.` ~keep
//!
//! Split into its own file so `tests.rs` (984 lines) stays under the `file-modularization` cap.

use super::cargo::gen_cargo_toml;
use crate::core::config::{Language, NewAlefConfig, ResolvedCrateConfig};
use crate::core::ir::{ApiSurface, TypeDef};

/// The shape that broke, reduced to its two features: a native-only one the core crate turns on by
/// default (pulling tokio's `net`, hence mio), and the wasm-only replacement the binding asks for.
const CORE_FEATURES_BODY: &str = r#"default = ["native-http"]
native-http = ["dep:tokio", "tokio/net"]
wasm-http = ["dep:gloo-timers"]
"#;

fn write_core_manifest(dir: &std::path::Path) {
    let core_dir = dir.join("crates").join("test-lib");
    std::fs::create_dir_all(&core_dir).expect("create core crate dir");
    std::fs::write(
        core_dir.join("Cargo.toml"),
        format!("[package]\nname = \"test-lib\"\n\n[features]\n{CORE_FEATURES_BODY}"),
    )
    .expect("write core Cargo.toml");
}

/// `wasm_table` is the body of `[crates.wasm]` -- empty for "configure no features at all".
fn config_with_core_manifest(dir: &std::path::Path, wasm_table: &str) -> ResolvedCrateConfig {
    write_core_manifest(dir);
    let toml_src = format!(
        r#"
[workspace]
languages = ["wasm"]
[[crates]]
name = "test-lib"
sources = ["crates/test-lib/src/lib.rs"]
workspace_root = "{root}"
[crates.wasm]
{wasm_table}
"#,
        // TOML strings treat `\` as an escape, so a Windows temp path must be forward-slashed
        // before it is interpolated; Cargo and alef both accept `/` separators on every host. ~keep
        root = dir.display().to_string().replace('\\', "/"),
    );
    let cfg: NewAlefConfig = toml::from_str(&toml_src).expect("valid alef config");
    cfg.resolve().expect("resolve").remove(0)
}

/// One type gated on both feature names, so `collect_cfg_features` discovers `native-http` and
/// `wasm-http` and the manifest grows a forwarding row for each.
fn api_gated_on_both_features() -> ApiSurface {
    ApiSurface {
        crate_name: "test-lib".to_string(),
        version: "0.1.0".to_string(),
        types: vec![TypeDef {
            name: "Client".to_string(),
            rust_path: "test_lib::Client".to_string(),
            cfg: Some(r#"any(feature = "native-http", feature = "wasm-http")"#.to_string()),
            ..Default::default()
        }],
        ..Default::default()
    }
}

fn features_block(cargo_toml: &str) -> String {
    let start = cargo_toml
        .find("[features]\n")
        .unwrap_or_else(|| panic!("no [features] table in:\n{cargo_toml}"));
    let body = &cargo_toml[start..];
    let end = body
        .find("\n\n")
        .unwrap_or_else(|| panic!("unterminated [features] table in:\n{cargo_toml}"));
    body[..end].to_string()
}

fn dependency_line(cargo_toml: &str, name: &str) -> String {
    let prefix = format!("{name} = ");
    cargo_toml
        .lines()
        .find(|line| line.starts_with(&prefix))
        .unwrap_or_else(|| panic!("no `{name}` dependency line in:\n{cargo_toml}"))
        .to_string()
}

/// THE LEAK. Reverting `core_default_features_active`'s `Language::Wasm` arm makes this fail with
/// `default = ["native-http", "wasm-http"]` -- the byte-for-byte shape a downstream crate shipped, and the
/// one that dragged mio into a wasm32 build.
#[test]
fn wasm_features_default_excludes_a_core_default_the_dependency_line_disabled() {
    let dir = tempfile::tempdir().expect("tempdir");
    let config = config_with_core_manifest(dir.path(), r#"features = ["wasm-http"]"#);
    let cargo_toml = gen_cargo_toml(&api_gated_on_both_features(), &config);

    assert_eq!(
        features_block(&cargo_toml),
        "[features]\ndefault = [\"wasm-http\"]\n\
         native-http = [\"test-lib/native-http\"]\n\
         wasm-http = [\"test-lib/wasm-http\"]",
        "`native-http` must stay declared-but-off: the core dep line already turned it off, and \
         defaulting it back on re-enables the native tokio stack on wasm32:\n{cargo_toml}"
    );
    toml::from_str::<toml::Value>(&cargo_toml).expect("generated wasm Cargo.toml must be valid TOML");
}

/// The other half of the same contract, pinned separately so a regression tells you WHICH of the
/// two disagreeing emissions moved. This line is already correct today; it is the `[features]`
/// table that contradicted it, so this must not change when the fix is reverted -- which is
/// exactly what makes the pair diagnostic.
#[test]
fn wasm_core_dependency_line_disables_default_features_and_names_only_the_wasm_set() {
    let dir = tempfile::tempdir().expect("tempdir");
    let config = config_with_core_manifest(dir.path(), r#"features = ["wasm-http"]"#);
    let cargo_toml = gen_cargo_toml(&api_gated_on_both_features(), &config);

    let core_path = config.core_crate_dep_path_for_language(&super::wasm_output_layout(&config).root, Language::Wasm);
    assert_eq!(
        dependency_line(&cargo_toml, "test-lib"),
        format!(r#"test-lib = {{ path = "{core_path}", default-features = false, features = ["wasm-http"] }}"#),
        "the core dep edge must suppress defaults and request exactly the configured wasm set:\n{cargo_toml}"
    );
}

/// DO-NOT-OVER-NARROW CONTROL. With no wasm feature list configured, `gen_cargo_toml` emits a
/// plain dependency line with no `default-features = false`, so the core crate's `default` really
/// IS active and the `[features]` table must keep saying so. A "fix" that suppressed core
/// defaults for wasm unconditionally would fail here with `default = ["wasm-http"]` while the
/// dependency line it must agree with still leaves `native-http` on -- the same disagreement,
/// mirrored.
#[test]
fn wasm_features_default_keeps_core_defaults_when_no_wasm_feature_list_is_configured() {
    let dir = tempfile::tempdir().expect("tempdir");
    let config = config_with_core_manifest(dir.path(), "");
    let cargo_toml = gen_cargo_toml(&api_gated_on_both_features(), &config);

    let core_path = config.core_crate_dep_path_for_language(&super::wasm_output_layout(&config).root, Language::Wasm);
    assert_eq!(
        dependency_line(&cargo_toml, "test-lib"),
        format!(r#"test-lib = {{ path = "{core_path}" }}"#),
        "sanity: with nothing configured the dep line must leave the core defaults alone:\n{cargo_toml}"
    );
    assert_eq!(
        features_block(&cargo_toml),
        "[features]\ndefault = [\"native-http\"]\n\
         native-http = [\"test-lib/native-http\"]\n\
         wasm-http = [\"test-lib/wasm-http\"]",
        "a core default that IS active on this dep edge must still be defaulted on:\n{cargo_toml}"
    );
}

// The native halves of this contract live where their emitters do, because `scaffold_python_cargo`
// is not reachable from here: `scaffold::languages::python::scaffold_python_cargo` manifest control
// in `scaffold::languages::python`, and the `enabled_features_for_language` control in
// `codegen::cfg::tests::enabled_features`. ~keep