[beta-1.68] Backport fixes of split-debuginfo detection

Cargo.toml

@@ -44,7 +44,9 @@ jobserver = "0.1.24"
 lazycell = "1.2.0"
 libc = "0.2"
 log = "0.4.6"
-libgit2-sys = "0.14.1"
+# Temporarily pin libgit2-sys due to some issues with SSH not working on
+# Windows.
+libgit2-sys = "=0.14.1"
 memchr = "2.1.3"
 opener = "0.5"
 os_info = "3.5.0"
@@ -68,7 +70,7 @@ toml_edit =  { version = "0.15.0", features = ["serde", "easy", "perf"] }
 unicode-xid = "0.2.0"
 url = "2.2.2"
 walkdir = "2.2"
-clap = "4.1.1"
+clap = "4.1.3"
 unicode-width = "0.1.5"
 openssl = { version = '0.10.11', optional = true }
 im-rc = "15.0.0"

src/cargo/core/compiler/build_context/target_info.rs

@@ -12,6 +12,7 @@ use crate::core::compiler::{
 };
 use crate::core::{Dependency, Package, Target, TargetKind, Workspace};
 use crate::util::config::{Config, StringList, TargetConfig};
+use crate::util::interning::InternedString;
 use crate::util::{CargoResult, Rustc};
 use anyhow::Context as _;
 use cargo_platform::{Cfg, CfgExpr};
@@ -43,6 +44,8 @@ pub struct TargetInfo {
     crate_types: RefCell<HashMap<CrateType, Option<(String, String)>>>,
     /// `cfg` information extracted from `rustc --print=cfg`.
     cfg: Vec<Cfg>,
+    /// Supported values for `-Csplit-debuginfo=` flag, queried from rustc
+    support_split_debuginfo: Vec<String>,
     /// Path to the sysroot.
     pub sysroot: PathBuf,
     /// Path to the "lib" or "bin" directory that rustc uses for its dynamic
@@ -55,8 +58,6 @@ pub struct TargetInfo {
     pub rustflags: Vec<String>,
     /// Extra flags to pass to `rustdoc`, see [`extra_args`].
     pub rustdocflags: Vec<String>,
-    /// Whether or not rustc supports the `-Csplit-debuginfo` flag.
-    pub supports_split_debuginfo: bool,
 }
 
 /// Kind of each file generated by a Unit, part of `FileType`.
@@ -170,7 +171,8 @@ impl TargetInfo {
             // Query rustc for several kinds of info from each line of output:
             // 0) file-names (to determine output file prefix/suffix for given crate type)
             // 1) sysroot
-            // 2) cfg
+            // 2) split-debuginfo
+            // 3) cfg
             //
             // Search `--print` to see what we query so far.
             let mut process = rustc.workspace_process();
@@ -199,15 +201,9 @@ impl TargetInfo {
                 process.arg("--crate-type").arg(crate_type.as_str());
             }
 
-            // An extra `rustc` call to determine `-Csplit-debuginfo=packed` support.
-            let supports_split_debuginfo = rustc
-                .cached_output(
-                    process.clone().arg("-Csplit-debuginfo=packed"),
-                    extra_fingerprint,
-                )
-                .is_ok();
-
             process.arg("--print=sysroot");
+            process.arg("--print=split-debuginfo");
+            process.arg("--print=crate-name"); // `___` as a delimiter.
             process.arg("--print=cfg");
 
             let (output, error) = rustc
@@ -223,13 +219,8 @@ impl TargetInfo {
                 map.insert(crate_type.clone(), out);
             }
 
-            let line = match lines.next() {
-                Some(line) => line,
-                None => anyhow::bail!(
-                    "output of --print=sysroot missing when learning about \
-                 target-specific information from rustc\n{}",
-                    output_err_info(&process, &output, &error)
-                ),
+            let Some(line) = lines.next() else {
+                return error_missing_print_output("sysroot", &process, &output, &error);
             };
             let sysroot = PathBuf::from(line);
             let sysroot_host_libdir = if cfg!(windows) {
@@ -246,6 +237,26 @@ impl TargetInfo {
             });
             sysroot_target_libdir.push("lib");
 
+            let support_split_debuginfo = {
+                // HACK: abuse `--print=crate-name` to use `___` as a delimiter.
+                let mut res = Vec::new();
+                loop {
+                    match lines.next() {
+                        Some(line) if line == "___" => break,
+                        Some(line) => res.push(line.into()),
+                        None => {
+                            return error_missing_print_output(
+                                "split-debuginfo",
+                                &process,
+                                &output,
+                                &error,
+                            )
+                        }
+                    }
+                }
+                res
+            };
+
             let cfg = lines
                 .map(|line| Ok(Cfg::from_str(line)?))
                 .filter(TargetInfo::not_user_specific_cfg)
@@ -303,7 +314,7 @@ impl TargetInfo {
                     Flags::Rustdoc,
                 )?,
                 cfg,
-                supports_split_debuginfo,
+                support_split_debuginfo,
             });
         }
     }
@@ -543,6 +554,13 @@ impl TargetInfo {
         }
         Ok((result, unsupported))
     }
+
+    /// Checks if the debuginfo-split value is supported by this target
+    pub fn supports_debuginfo_split(&self, split: InternedString) -> bool {
+        self.support_split_debuginfo
+            .iter()
+            .any(|sup| sup.as_str() == split.as_str())
+    }
 }
 
 /// Takes rustc output (using specialized command line args), and calculates the file prefix and
@@ -578,17 +596,27 @@ fn parse_crate_type(
     };
     let mut parts = line.trim().split("___");
     let prefix = parts.next().unwrap();
-    let suffix = match parts.next() {
-        Some(part) => part,
-        None => anyhow::bail!(
-            "output of --print=file-names has changed in the compiler, cannot parse\n{}",
-            output_err_info(cmd, output, error)
-        ),
+    let Some(suffix) = parts.next() else {
+        return error_missing_print_output("file-names", cmd, output, error);
     };
 
     Ok(Some((prefix.to_string(), suffix.to_string())))
 }
 
+/// Helper for creating an error message for missing output from a certain `--print` request.
+fn error_missing_print_output<T>(
+    request: &str,
+    cmd: &ProcessBuilder,
+    stdout: &str,
+    stderr: &str,
+) -> CargoResult<T> {
+    let err_info = output_err_info(cmd, stdout, stderr);
+    anyhow::bail!(
+        "output of --print={request} missing when learning about \
+     target-specific information from rustc\n{err_info}",
+    )
+}
+
 /// Helper for creating an error message when parsing rustc output fails.
 fn output_err_info(cmd: &ProcessBuilder, stdout: &str, stderr: &str) -> String {
     let mut result = format!("command was: {}\n", cmd);

src/cargo/core/compiler/mod.rs

@@ -980,10 +980,17 @@ fn build_base_args(
     cmd.args(&lto_args(cx, unit));
 
     // This is generally just an optimization on build time so if we don't pass
-    // it then it's ok. As of the time of this writing it's a very new flag, so
-    // we need to dynamically check if it's available.
-    if cx.bcx.target_data.info(unit.kind).supports_split_debuginfo {
-        if let Some(split) = split_debuginfo {
+    // it then it's ok. The values for the flag (off, packed, unpacked) may be supported
+    // or not depending on the platform, so availability is checked per-value.
+    // For example, at the time of writing this code, on Windows the only stable valid
+    // value for split-debuginfo is "packed", while on Linux "unpacked" is also stable.
+    if let Some(split) = split_debuginfo {
+        if cx
+            .bcx
+            .target_data
+            .info(unit.kind)
+            .supports_debuginfo_split(split)
+        {
             cmd.arg("-C").arg(format!("split-debuginfo={}", split));
         }
     }

tests/testsuite/cargo_add/invalid_arg/stderr.log

@@ -1,6 +1,6 @@
 error: unexpected argument '--flag' found
 
-  note: to pass '--flag' as a value, use '-- --flag'
+  note: argument '--tag' exists
 
 Usage: cargo add [OPTIONS] <DEP>[@<VERSION>] ...
        cargo add [OPTIONS] --path <PATH> ...

tests/testsuite/cfg.rs

@@ -356,6 +356,22 @@ fn bad_cfg_discovery() {
                     return;
                 }
                 println!("{}", sysroot);
+
+                if mode == "no-split-debuginfo" {
+                    return;
+                }
+                loop {
+                    let line = lines.next().unwrap();
+                    if line == "___" {
+                        println!("\n{line}");
+                        break;
+                    } else {
+                        // As the number split-debuginfo options varies,
+                        // concat them into one line.
+                        print!("{line},");
+                    }
+                };
+
                 if mode != "bad-cfg" {
                     panic!("unexpected");
                 }
@@ -412,6 +428,28 @@ command was: `[..]compiler[..]--crate-type [..]`
 [..]___[..]
 [..]___[..]
 
+",
+        )
+        .run();
+
+    p.cargo("build")
+        .env("RUSTC", &funky_rustc)
+        .env("FUNKY_MODE", "no-split-debuginfo")
+        .with_status(101)
+        .with_stderr(
+            "\
+[ERROR] output of --print=split-debuginfo missing when learning about target-specific information from rustc
+command was: `[..]compiler[..]--crate-type [..]`
+
+--- stdout
+[..]___[..]
+[..]___[..]
+[..]___[..]
+[..]___[..]
+[..]___[..]
+[..]___[..]
+[..]
+
 ",
         )
         .run();
@@ -430,6 +468,8 @@ command was: `[..]compiler[..]--crate-type [..]`
 [..]___[..]
 [..]___[..]
 [..]
+[..],[..]
+___
 123
 
 

tests/testsuite/ssh.rs

@@ -386,6 +386,10 @@ Caused by:
 }
 
 #[cargo_test(public_network_test)]
+// For unknown reasons, this test occasionally fails on Windows with a
+// LIBSSH2_ERROR_KEY_EXCHANGE_FAILURE error:
+//     failed to start SSH session: Unable to exchange encryption keys; class=Ssh (23)
+#[cfg_attr(windows, ignore = "test is flaky on windows")]
 fn invalid_github_key() {
     // A key for github.com in known_hosts should override the built-in key.
     // This uses a bogus key which should result in an error.
@@ -417,6 +421,10 @@ fn invalid_github_key() {
 }
 
 #[cargo_test(public_network_test)]
+// For unknown reasons, this test occasionally fails on Windows with a
+// LIBSSH2_ERROR_KEY_EXCHANGE_FAILURE error:
+//     failed to start SSH session: Unable to exchange encryption keys; class=Ssh (23)
+#[cfg_attr(windows, ignore = "test is flaky on windows")]
 fn bundled_github_works() {
     // The bundled key for github.com works.
     //