Teach cargo to failfast on recursive/corecursive aliases

Eg.
[alias]
test-1 = test-2
test-2 = test-3
test-3 = test-1

Previously it would stack overflow

It pulls out non controversial bits from from rust-lang#9768

Author: nipunn1313

src/bin/cargo/cli.rs

@@ -1,3 +1,4 @@
+use anyhow::anyhow;
 use cargo::core::{features, CliUnstable};
 use cargo::{self, drop_print, drop_println, CliResult, Config};
 use clap::{AppSettings, Arg, ArgMatches};
@@ -123,7 +124,7 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'",
     // Global args need to be extracted before expanding aliases because the
     // clap code for extracting a subcommand discards global options
     // (appearing before the subcommand).
-    let (expanded_args, global_args) = expand_aliases(config, args)?;
+    let (expanded_args, global_args) = expand_aliases(config, args, vec![])?;
     let (cmd, subcommand_args) = match expanded_args.subcommand() {
         (cmd, Some(args)) => (cmd, args),
         _ => {
@@ -159,6 +160,7 @@ pub fn get_version_string(is_verbose: bool) -> String {
 fn expand_aliases(
     config: &mut Config,
     args: ArgMatches<'static>,
+    mut already_expanded: Vec<String>,
 ) -> Result<(ArgMatches<'static>, GlobalArgs), CliError> {
     if let (cmd, Some(args)) = args.subcommand() {
         match (
@@ -197,7 +199,21 @@ fn expand_aliases(
                 let new_args = cli()
                     .setting(AppSettings::NoBinaryName)
                     .get_matches_from_safe(alias)?;
-                let (expanded_args, _) = expand_aliases(config, new_args)?;
+
+                let (new_cmd, _) = new_args.subcommand();
+                already_expanded.push(cmd.to_string());
+                if already_expanded.contains(&new_cmd.to_string()) {
+                    // Crash if the aliases are corecursive / unresolvable
+                    return Err(anyhow!(
+                        "alias {} has unresolvable recursive definition: {} -> {}",
+                        already_expanded[0],
+                        already_expanded.join(" -> "),
+                        new_cmd,
+                    )
+                    .into());
+                }
+
+                let (expanded_args, _) = expand_aliases(config, new_args, already_expanded)?;
                 return Ok((expanded_args, global_args));
             }
         }

tests/testsuite/cargo_alias_config.rs

@@ -1,5 +1,8 @@
 //! Tests for `[alias]` config command aliases.
 
+use std::env;
+
+use cargo_test_support::tools::echo_subcommand;
 use cargo_test_support::{basic_bin_manifest, project};
 
 #[cargo_test]
@@ -50,7 +53,7 @@ fn alias_config() {
 }
 
 #[cargo_test]
-fn recursive_alias() {
+fn dependent_alias() {
     let p = project()
         .file("Cargo.toml", &basic_bin_manifest("foo"))
         .file("src/main.rs", "fn main() {}")
@@ -73,6 +76,84 @@ fn recursive_alias() {
         .run();
 }
 
+#[cargo_test]
+fn default_args_alias() {
+    let echo = echo_subcommand();
+    let p = project()
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file("src/main.rs", "fn main() {}")
+        .file(
+            ".cargo/config",
+            r#"
+                [alias]
+                echo = "echo --flag1 --flag2"
+                test-1 = "echo"
+                build = "build --verbose"
+            "#,
+        )
+        .build();
+
+    let mut paths: Vec<_> = env::split_paths(&env::var_os("PATH").unwrap_or_default()).collect();
+    paths.push(echo.target_debug_dir());
+    let path = env::join_paths(paths).unwrap();
+
+    p.cargo("echo")
+        .env("PATH", &path)
+        .with_status(101)
+        .with_stderr("error: alias echo has unresolvable recursive definition: echo -> echo")
+        .run();
+
+    p.cargo("test-1")
+        .env("PATH", &path)
+        .with_status(101)
+        .with_stderr(
+            "error: alias test-1 has unresolvable recursive definition: test-1 -> echo -> echo",
+        )
+        .run();
+
+    // Builtins are not expanded by rule
+    p.cargo("build")
+        .with_stderr(
+            "\
+[WARNING] user-defined alias `build` is ignored, because it is shadowed by a built-in command
+[COMPILING] foo v0.5.0 ([..])
+[FINISHED] dev [unoptimized + debuginfo] target(s) in [..]
+",
+        )
+        .run();
+}
+
+#[cargo_test]
+fn corecursive_alias() {
+    let p = project()
+        .file("Cargo.toml", &basic_bin_manifest("foo"))
+        .file("src/main.rs", "fn main() {}")
+        .file(
+            ".cargo/config",
+            r#"
+                [alias]
+                test-1 = "test-2 --flag1"
+                test-2 = "test-3 --flag2"
+                test-3 = "test-1 --flag3"
+            "#,
+        )
+        .build();
+
+    p.cargo("test-1")
+        .with_status(101)
+        .with_stderr(
+            "error: alias test-1 has unresolvable recursive definition: test-1 -> test-2 -> test-3 -> test-1",
+        )
+        .run();
+
+    p.cargo("test-2")
+        .with_status(101)
+        .with_stderr(
+            "error: alias test-2 has unresolvable recursive definition: test-2 -> test-3 -> test-1 -> test-2",
+        )
+        .run();
+}
+
 #[cargo_test]
 fn alias_list_test() {
     let p = project()