Rollup merge of rust-lang#148317 - Zalathar:cli-paths-mod, r=Kobzol

bootstrap: Extract parts of `bootstrap::core::builder` into a `cli_paths` module

One of the things that makes bootstrap's CLI path handling hard to work with is the fact that it's in the middle of a ~2000 line file full of all sorts of other things. And the primary code sequence is in an unhelpfully-named `StepDescription::run` function.

This PR therefore pulls some key chunks of code out into a `cli_paths` submodule.

This should be a purely non-functional change.

Author: Zalathar

src/bootstrap/src/core/builder/cli_paths.rs

@@ -0,0 +1,245 @@
+//! Various pieces of code for dealing with "paths" passed to bootstrap on the
+//! command-line, extracted from `core/builder/mod.rs` because that file is
+//! large and hard to navigate.
+
+use std::fmt::{self, Debug};
+use std::path::PathBuf;
+
+use crate::core::builder::{Builder, Kind, PathSet, ShouldRun, StepDescription};
+
+pub(crate) const PATH_REMAP: &[(&str, &[&str])] = &[
+    // bootstrap.toml uses `rust-analyzer-proc-macro-srv`, but the
+    // actual path is `proc-macro-srv-cli`
+    ("rust-analyzer-proc-macro-srv", &["src/tools/rust-analyzer/crates/proc-macro-srv-cli"]),
+    // Make `x test tests` function the same as `x t tests/*`
+    (
+        "tests",
+        &[
+            // tidy-alphabetical-start
+            "tests/assembly-llvm",
+            "tests/codegen-llvm",
+            "tests/codegen-units",
+            "tests/coverage",
+            "tests/coverage-run-rustdoc",
+            "tests/crashes",
+            "tests/debuginfo",
+            "tests/incremental",
+            "tests/mir-opt",
+            "tests/pretty",
+            "tests/run-make",
+            "tests/run-make-cargo",
+            "tests/rustdoc",
+            "tests/rustdoc-gui",
+            "tests/rustdoc-js",
+            "tests/rustdoc-js-std",
+            "tests/rustdoc-json",
+            "tests/rustdoc-ui",
+            "tests/ui",
+            "tests/ui-fulldeps",
+            // tidy-alphabetical-end
+        ],
+    ),
+];
+
+pub(crate) fn remap_paths(paths: &mut Vec<PathBuf>) {
+    let mut remove = vec![];
+    let mut add = vec![];
+    for (i, path) in paths.iter().enumerate().filter_map(|(i, path)| path.to_str().map(|s| (i, s)))
+    {
+        for &(search, replace) in PATH_REMAP {
+            // Remove leading and trailing slashes so `tests/` and `tests` are equivalent
+            if path.trim_matches(std::path::is_separator) == search {
+                remove.push(i);
+                add.extend(replace.iter().map(PathBuf::from));
+                break;
+            }
+        }
+    }
+    remove.sort();
+    remove.dedup();
+    for idx in remove.into_iter().rev() {
+        paths.remove(idx);
+    }
+    paths.append(&mut add);
+}
+
+#[derive(Clone, PartialEq)]
+pub(crate) struct CLIStepPath {
+    pub(crate) path: PathBuf,
+    pub(crate) will_be_executed: bool,
+}
+
+#[cfg(test)]
+impl CLIStepPath {
+    pub(crate) fn will_be_executed(mut self, will_be_executed: bool) -> Self {
+        self.will_be_executed = will_be_executed;
+        self
+    }
+}
+
+impl Debug for CLIStepPath {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.path.display())
+    }
+}
+
+impl From<PathBuf> for CLIStepPath {
+    fn from(path: PathBuf) -> Self {
+        Self { path, will_be_executed: false }
+    }
+}
+
+/// Combines a `StepDescription` with its corresponding `ShouldRun`.
+struct StepExtra<'a> {
+    desc: &'a StepDescription,
+    should_run: ShouldRun<'a>,
+}
+
+struct StepToRun<'a> {
+    sort_index: usize,
+    desc: &'a StepDescription,
+    pathsets: Vec<PathSet>,
+}
+
+pub(crate) fn match_paths_to_steps_and_run(
+    builder: &Builder<'_>,
+    step_descs: &[StepDescription],
+    paths: &[PathBuf],
+) {
+    // Obtain `ShouldRun` information for each step, so that we know which
+    // paths to match it against.
+    let steps = step_descs
+        .iter()
+        .map(|desc| StepExtra {
+            desc,
+            should_run: (desc.should_run)(ShouldRun::new(builder, desc.kind)),
+        })
+        .collect::<Vec<_>>();
+
+    // FIXME(Zalathar): This particular check isn't related to path-to-step
+    // matching, and should probably be hoisted to somewhere much earlier.
+    if builder.download_rustc() && (builder.kind == Kind::Dist || builder.kind == Kind::Install) {
+        eprintln!(
+            "ERROR: '{}' subcommand is incompatible with `rust.download-rustc`.",
+            builder.kind.as_str()
+        );
+        crate::exit!(1);
+    }
+
+    // sanity checks on rules
+    for StepExtra { desc, should_run } in &steps {
+        assert!(!should_run.paths.is_empty(), "{:?} should have at least one pathset", desc.name);
+    }
+
+    if paths.is_empty() || builder.config.include_default_paths {
+        for StepExtra { desc, should_run } in &steps {
+            if desc.default && should_run.is_really_default() {
+                desc.maybe_run(builder, should_run.paths.iter().cloned().collect());
+            }
+        }
+    }
+
+    // Attempt to resolve paths to be relative to the builder source directory.
+    let mut paths: Vec<PathBuf> = paths
+        .iter()
+        .map(|original_path| {
+            let mut path = original_path.clone();
+
+            // Someone could run `x <cmd> <path>` from a different repository than the source
+            // directory.
+            // In that case, we should not try to resolve the paths relative to the working
+            // directory, but rather relative to the source directory.
+            // So we forcefully "relocate" the path to the source directory here.
+            if !path.is_absolute() {
+                path = builder.src.join(path);
+            }
+
+            // If the path does not exist, it may represent the name of a Step, such as `tidy` in `x test tidy`
+            if !path.exists() {
+                // Use the original path here
+                return original_path.clone();
+            }
+
+            // Make the path absolute, strip the prefix, and convert to a PathBuf.
+            match std::path::absolute(&path) {
+                Ok(p) => p.strip_prefix(&builder.src).unwrap_or(&p).to_path_buf(),
+                Err(e) => {
+                    eprintln!("ERROR: {e:?}");
+                    panic!("Due to the above error, failed to resolve path: {path:?}");
+                }
+            }
+        })
+        .collect();
+
+    remap_paths(&mut paths);
+
+    // Handle all test suite paths.
+    // (This is separate from the loop below to avoid having to handle multiple paths in `is_suite_path` somehow.)
+    paths.retain(|path| {
+        for StepExtra { desc, should_run } in &steps {
+            if let Some(suite) = should_run.is_suite_path(path) {
+                desc.maybe_run(builder, vec![suite.clone()]);
+                return false;
+            }
+        }
+        true
+    });
+
+    if paths.is_empty() {
+        return;
+    }
+
+    let mut paths: Vec<CLIStepPath> = paths.into_iter().map(|p| p.into()).collect();
+    let mut path_lookup: Vec<(CLIStepPath, bool)> =
+        paths.clone().into_iter().map(|p| (p, false)).collect();
+
+    // Before actually running (non-suite) steps, collect them into a list of structs
+    // so that we can then sort the list to preserve CLI order as much as possible.
+    let mut steps_to_run = vec![];
+
+    for StepExtra { desc, should_run } in &steps {
+        let pathsets = should_run.pathset_for_paths_removing_matches(&mut paths, desc.kind);
+
+        // This value is used for sorting the step execution order.
+        // By default, `usize::MAX` is used as the index for steps to assign them the lowest priority.
+        //
+        // If we resolve the step's path from the given CLI input, this value will be updated with
+        // the step's actual index.
+        let mut closest_index = usize::MAX;
+
+        // Find the closest index from the original list of paths given by the CLI input.
+        for (index, (path, is_used)) in path_lookup.iter_mut().enumerate() {
+            if !*is_used && !paths.contains(path) {
+                closest_index = index;
+                *is_used = true;
+                break;
+            }
+        }
+
+        steps_to_run.push(StepToRun { sort_index: closest_index, desc, pathsets });
+    }
+
+    // Sort the steps before running them to respect the CLI order.
+    steps_to_run.sort_by_key(|step| step.sort_index);
+
+    // Handle all PathSets.
+    for StepToRun { sort_index: _, desc, pathsets } in steps_to_run {
+        if !pathsets.is_empty() {
+            desc.maybe_run(builder, pathsets);
+        }
+    }
+
+    paths.retain(|p| !p.will_be_executed);
+
+    if !paths.is_empty() {
+        eprintln!("ERROR: no `{}` rules matched {:?}", builder.kind.as_str(), paths);
+        eprintln!(
+            "HELP: run `x.py {} --help --verbose` to show a list of available paths",
+            builder.kind.as_str()
+        );
+        eprintln!(
+            "NOTE: if you are adding a new Step to bootstrap itself, make sure you register it with `describe!`"
+        );
+        crate::exit!(1);
+    }
+}