Extend the build directive syntax with cargo::metadata=

Signed-off-by: hi-rustin <[email protected]>

Author: 0xPoe

src/cargo/core/compiler/custom_build.rs

@@ -52,7 +52,8 @@ use std::sync::{Arc, Mutex};
 /// build script has finished running. Read [the doc] for more.
 ///
 /// [the doc]: https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#cargo-warning
-const CARGO_WARNING: &str = "cargo:warning=";
+const OLD_CARGO_WARNING_SYNTAX: &str = "cargo:warning=";
+const NEW_CARGO_WARNING_SYNTAX: &str = "cargo::warning=";
 
 /// Contains the parsed output of a custom build script.
 #[derive(Clone, Debug, Hash, Default)]
@@ -435,7 +436,10 @@ fn build_work(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Job> {
         let output = cmd
             .exec_with_streaming(
                 &mut |stdout| {
-                    if let Some(warning) = stdout.strip_prefix(CARGO_WARNING) {
+                    if let Some(warning) = stdout
+                        .strip_prefix(OLD_CARGO_WARNING_SYNTAX)
+                        .or(stdout.strip_prefix(NEW_CARGO_WARNING_SYNTAX))
+                    {
                         warnings_in_case_of_panic.push(warning.to_owned());
                     }
                     if extra_verbose {
@@ -643,28 +647,93 @@ impl BuildOutput {
                 Ok(line) => line.trim(),
                 Err(..) => continue,
             };
-            let mut iter = line.splitn(2, ':');
+            let mut new_syntax = true;
+            let mut iter = line.splitn(2, "::");
             if iter.next() != Some("cargo") {
-                // skip this line since it doesn't start with "cargo:"
-                continue;
+                // For backwards compatibility, we also accept lines that start with "cargo:".
+                new_syntax = false;
+                iter = line.splitn(2, ":");
+                if iter.next() != Some("cargo") {
+                    // skip this line since it doesn't start with "cargo:" or "cargo::".
+                    continue;
+                }
             }
             let data = match iter.next() {
                 Some(val) => val,
                 None => continue,
             };
 
-            // getting the `key=value` part of the line
-            let mut iter = data.splitn(2, '=');
-            let key = iter.next();
-            let value = iter.next();
-            let (key, value) = match (key, value) {
-                (Some(a), Some(b)) => (a, b.trim_end()),
-                // Line started with `cargo:` but didn't match `key=value`.
-                _ => bail!("invalid output in {}: `{}`\n\
-                    Expected a line with `cargo:key=value` with an `=` character, \
-                    but none was found.\n\
-                    See https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script \
-                    for more information about build script outputs.", whence, line),
+            // Old syntax:
+            //    cargo:rustc-flags=VALUE
+            //    cargo:KEY=VALUE (for other unreserved keys)
+            // New syntax:
+            //    cargo::rustc-flags=VALUE
+            //    cargo::metadata=KEY=VALUE (for other unreserved keys)
+            const RESERVED_KEYS: &[&str] = &[
+                "rustc-flags",
+                "rustc-link-lib",
+                "rustc-link-search",
+                "rustc-link-arg-cdylib",
+                "rustc-link-arg-bins",
+                "rustc-link-arg-bin",
+                "rustc-link-arg-tests",
+                "rustc-link-arg-benches",
+                "rustc-link-arg-examples",
+                "rustc-link-arg",
+                "rustc-cfg",
+                "rustc-check-cfg",
+                "rustc-env",
+                "warning",
+                "rerun-if-changed",
+                "rerun-if-env-changed",
+            ];
+            const DOCS_LINK_SUGGESTION: &str = "See https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script \
+                for more information about build script outputs.";
+            let mut iter = data.splitn(3, '=');
+            let part1 = iter.next();
+            let part2 = iter.next();
+            let part3 = iter.next();
+            let (key, value) = match (part1, part2, part3) {
+                // For instance, `cargo::metadata=foo=bar`.
+                (Some("metadata"), Some(a), Some(b)) => {
+                    // `cargo::metadata=` should only be used with the new syntax.
+                    if !new_syntax {
+                        bail!("invalid output in {}: `{}`\n\
+                            Expected a line with `cargo::KEY=VALUE`, but found `cargo:metadata=KEY=VALUE`.\n\
+                            {}", whence, line, DOCS_LINK_SUGGESTION
+                        )
+                    }
+                    // Reserved keys should not be used with the `cargo::metadata` syntax.
+                    if new_syntax && RESERVED_KEYS.contains(&a) {
+                        bail!("invalid output in {}: `{}`\n\
+                            The reserved key `{}` cannot be used in a `cargo::metadata` line. Please use `cargo::{}=VAlUE` instead.\n\
+                            {}", whence, line, a, a, DOCS_LINK_SUGGESTION
+                        )
+                    }
+                    (a, b.trim_end().to_owned())
+                }
+                // For instance, `cargo::warning=foo` or `cargo:warning=foo`.
+                (Some(a), Some(b), None) => {
+                    // Only reserved keys should be used with the `cargo::` syntax.
+                    // Otherwise, it should be `cargo::metadata=KEY=VALUE`.
+                    if new_syntax && !RESERVED_KEYS.contains(&a) {
+                        bail!("invalid output in {}: `{}`\n\
+                            Expected a line with `cargo::metadata=KEY=VALUE` but it did not have the `metadata=` part.\n\
+                            {}", whence, line, DOCS_LINK_SUGGESTION
+                        )
+                    }
+                    (a, b.trim_end().to_owned())
+                }
+                // For instance, `cargo:rustc-link-search=[KIND=]PATH` or `cargo::rustc-link-search=[KIND=]PATH`.
+                (Some(a), Some(b), Some(c)) => (a, format!("{}={}", b, c).trim_end().to_owned()),
+                // Line started with `cargo:` or `cargo::` but didn't match any of the above.
+                _ => bail!(
+                    "invalid output in {}: `{}`\n\
+                    {}",
+                    whence,
+                    line,
+                    DOCS_LINK_SUGGESTION
+                ),
             };
 
             // This will rewrite paths if the target directory has been moved.