Pass the current cargo to run-make tests

A couple tests were using `BOOTSTRAP_CARGO` with `-Zbuild-std`, but that
stage0 cargo might not always be in sync with in-tree changes. In
particular, those tests started failing on the beta branch because the
older cargo couldn't find the library `Cargo.lock`, and then couldn't
build the latest version of `compiler_builtins` that had nightly changes.

Author: cuviper

Diff for: src/bootstrap/src/core/build_steps/test.rs

@@ -1733,6 +1733,11 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
 
         let is_rustdoc = suite.ends_with("rustdoc-ui") || suite.ends_with("rustdoc-js");
 
+        if mode == "run-make" {
+            let cargo = builder.ensure(tool::Cargo { compiler, target: compiler.host });
+            cmd.arg("--cargo-path").arg(cargo);
+        }
+
         // Avoid depending on rustdoc when we don't need it.
         if mode == "rustdoc"
             || mode == "run-make"

Diff for: src/tools/compiletest/src/common.rs

@@ -183,6 +183,9 @@ pub struct Config {
     /// The rustc executable.
     pub rustc_path: PathBuf,
 
+    /// The cargo executable.
+    pub cargo_path: Option<PathBuf>,
+
     /// The rustdoc executable.
     pub rustdoc_path: Option<PathBuf>,
 

Diff for: src/tools/compiletest/src/lib.rs

@@ -47,6 +47,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
     opts.reqopt("", "compile-lib-path", "path to host shared libraries", "PATH")
         .reqopt("", "run-lib-path", "path to target shared libraries", "PATH")
         .reqopt("", "rustc-path", "path to rustc to use for compiling", "PATH")
+        .optopt("", "cargo-path", "path to cargo to use for compiling", "PATH")
         .optopt("", "rustdoc-path", "path to rustdoc to use for compiling", "PATH")
         .optopt("", "coverage-dump-path", "path to coverage-dump to use in tests", "PATH")
         .reqopt("", "python", "path to python to use for doc tests", "PATH")
@@ -260,6 +261,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         compile_lib_path: make_absolute(opt_path(matches, "compile-lib-path")),
         run_lib_path: make_absolute(opt_path(matches, "run-lib-path")),
         rustc_path: opt_path(matches, "rustc-path"),
+        cargo_path: matches.opt_str("cargo-path").map(PathBuf::from),
         rustdoc_path: matches.opt_str("rustdoc-path").map(PathBuf::from),
         coverage_dump_path: matches.opt_str("coverage-dump-path").map(PathBuf::from),
         python: matches.opt_str("python").unwrap(),
@@ -364,6 +366,7 @@ pub fn log_config(config: &Config) {
     logv(c, format!("compile_lib_path: {:?}", config.compile_lib_path));
     logv(c, format!("run_lib_path: {:?}", config.run_lib_path));
     logv(c, format!("rustc_path: {:?}", config.rustc_path.display()));
+    logv(c, format!("cargo_path: {:?}", config.cargo_path));
     logv(c, format!("rustdoc_path: {:?}", config.rustdoc_path));
     logv(c, format!("src_base: {:?}", config.src_base.display()));
     logv(c, format!("build_base: {:?}", config.build_base.display()));

Diff for: src/tools/compiletest/src/runtest/run_make.rs

@@ -61,6 +61,10 @@ impl TestCx<'_> {
             .env_remove("MFLAGS")
             .env_remove("CARGO_MAKEFLAGS");
 
+        if let Some(ref cargo) = self.config.cargo_path {
+            cmd.env("CARGO", cwd.join(cargo));
+        }
+
         if let Some(ref rustdoc) = self.config.rustdoc_path {
             cmd.env("RUSTDOC", cwd.join(rustdoc));
         }
@@ -409,6 +413,10 @@ impl TestCx<'_> {
             // through a specific CI runner).
             .env("LLVM_COMPONENTS", &self.config.llvm_components);
 
+        if let Some(ref cargo) = self.config.cargo_path {
+            cmd.env("CARGO", source_root.join(cargo));
+        }
+
         if let Some(ref rustdoc) = self.config.rustdoc_path {
             cmd.env("RUSTDOC", source_root.join(rustdoc));
         }

Diff for: tests/run-make/compiler-builtins/rmake.rs

@@ -33,8 +33,8 @@ fn main() {
 
     let path = env_var("PATH");
     let rustc = env_var("RUSTC");
-    let bootstrap_cargo = env_var("BOOTSTRAP_CARGO");
-    let mut cmd = cmd(bootstrap_cargo);
+    let cargo = env_var("CARGO");
+    let mut cmd = cmd(cargo);
     cmd.args(&[
         "build",
         "--manifest-path",

Diff for: tests/run-make/thumb-none-cortex-m/rmake.rs

@@ -36,10 +36,10 @@ fn main() {
 
     let path = env_var("PATH");
     let rustc = env_var("RUSTC");
-    let bootstrap_cargo = env_var("BOOTSTRAP_CARGO");
-    // FIXME: extract bootstrap cargo invocations to a proper command
+    let cargo = env_var("CARGO");
+    // FIXME: extract cargo invocations to a proper command
     // https://github.com/rust-lang/rust/issues/128734
-    let mut cmd = cmd(bootstrap_cargo);
+    let mut cmd = cmd(cargo);
     cmd.args(&[
         "build",
         "--manifest-path",