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// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use anyhow::{anyhow, Result};
/// Converts a cargo platform-specific dependency target into GN imperative control flow.
///
/// `Cargo.toml` files can define [platform-specific dependencies] in two ways:
/// - Using `#[cfg]` syntax to match classes of targets.
/// ```text
/// [target.'cfg(unix)'.dependencies]
/// foo = "0.1"
/// ```
///
/// - Listing the full target the dependencies would apply to.
/// ```text
/// [target.aarch64-apple-darwin.dependencies]
/// bar = "0.1"
/// ```
///
/// This function is a wrapper around [`cfg_to_gn_conditional`] that converts full targets
/// into `#[cfg]` syntax.
///
/// [platform-specific dependencies]: https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#platform-specific-dependencies
pub fn target_to_gn_conditional(target: &str) -> Result<String> {
if target.starts_with("cfg") {
// This is #[cfg] syntax already.
cfg_to_gn_conditional(target)
} else if target.contains('-') {
// Handle this as a target triple. We only need to support targets in crates we
// depend on, so we use a simple exact match list that can be updated as needed.
let (target_arch, target_os) = match target {
"aarch64-apple-darwin" => ("aarch64", "macos"),
"riscv32i-unknown-none-elf" => ("riscv32i", "unknown"),
"riscv32imc-unknown-none-elf" => ("riscv32imc", "unknown"),
"thumbv6m-none-eabi" => ("thumbv6m", "unknown"),
// Return an error for unknown targets, to notify the dev that they should
// update this list.
_ => {
return Err(anyhow!(
"Unknown target: {}. Please add this to 'tools/cargo-gnaw/src/cfg.rs'.",
target
))
}
};
cfg_to_gn_conditional(&format!(
"cfg(all(target_arch = \"{}\", target_os = \"{}\"))",
target_arch, target_os
))
} else {
Err(anyhow!("Unknown platform-specific dependency target syntax: {}", target))
}
}
/// Convert a cargo cfg conditional into GN imperative control flow
// TODO This should consume some information in the Cargo.toml file
// to establish conventions for the carge -> GN build. This is hardcoded
// to support Fuchsia at the moment.
//
// wow. an interview question in real life.
pub fn cfg_to_gn_conditional(cfg: &str) -> Result<String> {
#[allow(clippy::if_same_then_else)]
if cfg.starts_with("cfg") {
Ok(cfg_to_gn_conditional(&cfg[4..cfg.len() - 1])?)
} else if cfg.starts_with("not") {
let section = &cfg[4..];
let mut paren_count = 1;
for (idx, c) in section.chars().enumerate() {
if c == ')' {
paren_count -= 1;
if paren_count == 0 {
return Ok(format!("!({})", cfg_to_gn_conditional(&section[..idx])?));
}
} else if c == '(' {
paren_count += 1;
}
}
Err(anyhow!("bad not statement"))
} else if cfg == "any()" {
Ok(String::from("true"))
} else if cfg.starts_with("any") {
let section = &cfg[4..cfg.len()];
let mut accum = vec![];
let mut paren_count = 1;
let mut start_idx = 0;
for (idx, c) in section.chars().enumerate() {
if c == ')' {
paren_count -= 1;
if paren_count == 0 {
accum.push(cfg_to_gn_conditional(&section[start_idx..idx])?);
}
} else if c == '(' {
paren_count += 1;
} else if c == ',' && paren_count <= 1 {
accum.push(cfg_to_gn_conditional(&section[start_idx..idx])?);
start_idx = idx + 2; // skip ", "
}
}
Ok(format!("({})", accum.join(" || ")))
} else if cfg.starts_with("all") {
let section = &cfg[4..cfg.len()];
let mut accum = vec![];
let mut paren_count = 1;
let mut start_idx = 0;
for (idx, c) in section.chars().enumerate() {
if c == ')' {
paren_count -= 1;
if paren_count == 0 {
accum.push(cfg_to_gn_conditional(&section[start_idx..idx])?);
}
} else if c == '(' {
paren_count += 1;
} else if c == ',' && paren_count <= 1 {
accum.push(cfg_to_gn_conditional(&section[start_idx..idx])?);
start_idx = idx + 2; // skip ", "
}
}
Ok(format!("({})", accum.join(" && ")))
} else if cfg == "target_os = \"fuchsia\"" {
Ok(String::from("current_os == \"fuchsia\""))
} else if cfg == "target_os = \"macos\"" {
Ok(String::from("current_os == \"mac\""))
} else if cfg == "target_os = \"linux\"" {
Ok(String::from("current_os == \"linux\""))
} else if cfg == "target_os = \"unknown\"" {
Ok(String::from("current_os == \"unknown\""))
} else if cfg == "unix" {
// all our platforms are unix
Ok(String::from("true"))
} else if cfg == "feature = \"std\"" {
// need to detect std usage
Ok(String::from("true"))
} else if cfg == "target_arch = \"aarch64\"" {
Ok(String::from("current_cpu == \"arm64\""))
} else if cfg == "target_arch = \"x86_64\"" {
Ok(String::from("current_cpu == \"x64\""))
} else if cfg == "target_arch = \"wasm32\"" {
Ok(String::from("current_cpu == \"wasm32\""))
} else if cfg == "target_arch = \"riscv32i\"" {
Ok(String::from("current_cpu == \"riscv32\""))
} else if cfg == "target_arch = \"riscv32imc\"" {
Ok(String::from("current_cpu == \"riscv32\""))
} else if cfg == "target_arch = \"thumbv6m\"" {
Ok(String::from("current_cpu == \"arm\""))
} else if cfg == "windows" || cfg == "target_family = \"windows\"" {
// don't support host builds on windows right now
Ok(String::from("false"))
// Everything below is random cfgs that we don't know anything about
} else if cfg.starts_with("target_os") {
Ok(String::from("false"))
} else if cfg.starts_with("target_arch") {
Ok(String::from("false"))
} else if cfg.starts_with("target_env") {
Ok(String::from("false"))
} else if cfg.starts_with("target_feature") {
Ok(String::from("false"))
} else if cfg.starts_with("target_vendor") {
Ok(String::from("false"))
} else if cfg.starts_with("tokio_taskdump") {
Ok(String::from("false"))
} else if cfg.starts_with("tokio_unstable") {
Ok(String::from("false"))
} else if cfg.starts_with("tracing_unstable") {
Ok(String::from("false"))
} else if cfg.starts_with("docsrs") {
Ok(String::from("false"))
} else {
// TODO(https://fxbug.dev/42061225) better handling needed for these cases.
Err(anyhow!("Unknown cfg option used: {}", cfg))
}
}
#[test]
fn basic_fuchsia() {
let cfg_str = r#"cfg(target_os = "fuchsia")"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(output, "current_os == \"fuchsia\"");
}
#[test]
fn conditonal_empty_any() {
let cfg_str = r#"cfg(any())"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(output, "true");
}
#[test]
fn conditonal_any() {
let cfg_str = r#"cfg(any(target_os = "fuchsia", target_os = "macos"))"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(output, "(current_os == \"fuchsia\" || current_os == \"mac\")");
}
#[test]
fn conditonal_all() {
let cfg_str = r#"cfg(all(target_os = "fuchsia", target_os = "macos"))"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(output, "(current_os == \"fuchsia\" && current_os == \"mac\")");
}
#[test]
fn conditonal_all_not() {
let cfg_str = r#"cfg(all(target_os = "fuchsia", not(target_os = "macos")))"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(output, "(current_os == \"fuchsia\" && !(current_os == \"mac\"))");
}
#[test]
fn conditonal_fail() {
let cfg_str = r#"cfg(everything(target_os = "fuchsia"))"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap_err();
assert_eq!(output.to_string(), r#"Unknown cfg option used: everything(target_os = "fuchsia")"#);
}
#[test]
fn nested_cfgs() {
let cfg_str =
r#"cfg(all(any(target_arch = "x86_64", target_arch = "aarch64"), target_os = "hermit"))"#;
let output = cfg_to_gn_conditional(cfg_str).unwrap();
assert_eq!(
output.to_string(),
r#"((current_cpu == "x64" || current_cpu == "arm64") && false)"#
);
}
#[test]
fn target_cfg() {
let target_str = r#"cfg(target_os = "fuchsia")"#;
let output = target_to_gn_conditional(target_str).unwrap();
assert_eq!(output, "current_os == \"fuchsia\"");
}
#[test]
fn target_full() {
let target_str = r#"aarch64-apple-darwin"#;
let output = target_to_gn_conditional(target_str).unwrap();
assert_eq!(output, "(current_cpu == \"arm64\" && current_os == \"mac\")");
}
#[test]
fn target_unknown_full() {
// We use a placeholder target "guaranteed" to never be used anywhere.
let target_str = r#"foo-bar-baz"#;
let err = target_to_gn_conditional(target_str).unwrap_err();
assert_eq!(
err.to_string(),
"Unknown target: foo-bar-baz. Please add this to 'tools/cargo-gnaw/src/cfg.rs'.",
);
}
#[test]
fn target_unknown_syntax() {
// No leading "cfg", no hyphens.
let target_str = r#"fizzbuzz"#;
let err = target_to_gn_conditional(target_str).unwrap_err();
assert_eq!(err.to_string(), "Unknown platform-specific dependency target syntax: fizzbuzz");
}