Add concrete examples for several config paths

Author: Zalathar

src/tools/compiletest/src/common.rs

@@ -248,13 +248,19 @@ pub struct Config {
 
     /// Path to libraries needed to run the *staged* `rustc`-under-test on the **host** platform.
     ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage1/bin/lib`
+    ///
     /// FIXME: maybe rename this to reflect (1) which target platform (host, not target), and (2)
     /// which `rustc` (the `rustc`-under-test, not the stage 0 `rustc` unless forced).
     pub compile_lib_path: Utf8PathBuf,
 
     /// Path to libraries needed to run the compiled executable for the **target** platform. This
     /// corresponds to the **target** sysroot libraries, including the **target** standard library.
     ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/i686-unknown-linux-gnu/lib`
+    ///
     /// FIXME: maybe rename this to reflect (1) which target platform (target, not host), and (2)
     /// what "run libraries" are against.
     ///
@@ -266,6 +272,9 @@ pub struct Config {
     /// Path to the *staged*  `rustc`-under-test. Unless forced, this `rustc` is *staged*, and must
     /// not be confused with [`Self::stage0_rustc_path`].
     ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage1/bin/rustc`
+    ///
     /// FIXME: maybe rename this to reflect that this is the `rustc`-under-test.
     pub rustc_path: Utf8PathBuf,
 
@@ -274,11 +283,17 @@ pub struct Config {
     /// *not* used to compile the test recipes), and so must be staged as there may be differences
     /// between e.g. beta `cargo` vs in-tree `cargo`.
     ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage1-tools-bin/cargo`
+    ///
     /// FIXME: maybe rename this to reflect that this is a *staged* host cargo.
     pub cargo_path: Option<Utf8PathBuf>,
 
     /// Path to the stage 0 `rustc` used to build `run-make` recipes. This must not be confused with
     /// [`Self::rustc_path`].
+    ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage0/bin/rustc`
     pub stage0_rustc_path: Option<Utf8PathBuf>,
 
     /// Path to the stage 1 or higher `rustc` used to obtain target information via
@@ -312,6 +327,9 @@ pub struct Config {
     pub llvm_filecheck: Option<Utf8PathBuf>,
 
     /// Path to a host LLVM bintools directory.
+    ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/llvm/bin`
     pub llvm_bin_dir: Option<Utf8PathBuf>,
 
     /// The path to the **target** `clang` executable to run `clang`-based tests with. If `None`,
@@ -321,28 +339,39 @@ pub struct Config {
     /// Path to the directory containing the sources. This corresponds to the root folder of a
     /// `rust-lang/rust` checkout.
     ///
+    /// For example:
+    /// - `/home/ferris/rust`
+    ///
     /// FIXME: this name is confusing, because this is actually `$checkout_root`, **not** the
     /// `$checkout_root/src/` folder.
     pub src_root: Utf8PathBuf,
 
-    /// Path to the directory containing the test suites sources. This corresponds to the
-    /// `$src_root/tests/` folder.
+    /// Absolute path to the test suite directory.
     ///
-    /// Must be an immediate subdirectory of [`Self::src_root`].
-    ///
-    /// FIXME: this name is also confusing, maybe just call it `tests_root`.
+    /// For example:
+    /// - `/home/ferris/rust/tests/ui`
+    /// - `/home/ferris/rust/tests/coverage`
     pub src_test_suite_root: Utf8PathBuf,
 
-    /// Path to the build directory (e.g. `build/`).
+    /// Path to the top-level build directory used by bootstrap.
+    ///
+    /// For example:
+    /// - `/home/ferris/rust/build`
     pub build_root: Utf8PathBuf,
 
-    /// Path to the test suite specific build directory (e.g. `build/host/test/ui/`).
+    /// Path to the build directory used by the current test suite.
     ///
-    /// Must be a subdirectory of [`Self::build_root`].
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/test/ui`
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/test/coverage`
     pub build_test_suite_root: Utf8PathBuf,
 
     /// Path to the directory containing the sysroot of the `rustc`-under-test.
     ///
+    /// For example:
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage1`
+    /// - `/home/ferris/rust/build/x86_64-unknown-linux-gnu/stage2`
+    ///
     /// When stage 0 is forced, this will correspond to the sysroot *of* that specified stage 0
     /// `rustc`.
     ///