Rollup merge of #130161 - onur-ozkan:fmt-changed-files, r=Kobzol,RalfJung

refactor merge base logic and fix `x fmt`

When remote upstream is not configured, using [get_git_modified_files](https://github.com/rust-lang/rust/blob/38e3a5771cefc9362976a605549f8b04d5707311/src/tools/build_helper/src/git.rs#L114) to find modified files fails because [get_rust_lang_rust_remote](https://github.com/rust-lang/rust/blob/38e3a5771cefc9362976a605549f8b04d5707311/src/tools/build_helper/src/git.rs#L46-L48) can not resolve "rust-lang/rust" from the git output. The changes in this PR makes bootstrap to find the latest bors commit, treating it as the "closest upstream commit" so that the change tracker logic can use it to find the diffs.

In addition, [skips formatting](https://github.com/rust-lang/rust/commit/e3924544832668a6e239153a90d3be2077fbdce4) if there are no modified files.

Fixes #130147

13 files changed, 79 insertions, 58 deletions

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 102c9fd2554..bb07d478f71 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -15,6 +15,7 @@ use std::path::{Path, PathBuf};
 use std::process::Stdio;
 use std::{env, fs, str};
 
+use build_helper::git::get_closest_merge_commit;
 use serde_derive::Deserialize;
 
 use crate::core::build_steps::tool::SourceType;
@@ -26,8 +27,7 @@ use crate::core::builder::{
 use crate::core::config::{DebuginfoLevel, LlvmLibunwind, RustcLto, TargetSelection};
 use crate::utils::exec::command;
 use crate::utils::helpers::{
-    self, exe, get_clang_cl_resource_dir, get_closest_merge_base_commit, is_debug_info, is_dylib,
-    symlink_dir, t, up_to_date,
+    self, exe, get_clang_cl_resource_dir, is_debug_info, is_dylib, symlink_dir, t, up_to_date,
 };
 use crate::{CLang, Compiler, DependencyType, GitRepo, Mode, LLVM_TOOLS};
 
@@ -127,13 +127,9 @@ impl Step for Std {
         // the `rust.download-rustc=true` option.
         let force_recompile =
             if builder.rust_info().is_managed_git_subrepository() && builder.download_rustc() {
-                let closest_merge_commit = get_closest_merge_base_commit(
-                    Some(&builder.src),
-                    &builder.config.git_config(),
-                    &builder.config.stage0_metadata.config.git_merge_commit_email,
-                    &[],
-                )
-                .unwrap();
+                let closest_merge_commit =
+                    get_closest_merge_commit(Some(&builder.src), &builder.config.git_config(), &[])
+                        .unwrap();
 
                 // Check if `library` has changes (returns false otherwise)
                 !t!(helpers::git(Some(&builder.src))
diff --git a/src/bootstrap/src/core/build_steps/format.rs b/src/bootstrap/src/core/build_steps/format.rs
index 91fbc57429a..bbd81fb570b 100644
--- a/src/bootstrap/src/core/build_steps/format.rs
+++ b/src/bootstrap/src/core/build_steps/format.rs
@@ -200,6 +200,11 @@ pub fn format(build: &Builder<'_>, check: bool, all: bool, paths: &[PathBuf]) {
                 adjective = Some("modified");
                 match get_modified_rs_files(build) {
                     Ok(Some(files)) => {
+                        if files.is_empty() {
+                            println!("fmt info: No modified files detected for formatting.");
+                            return;
+                        }
+
                         for file in files {
                             override_builder.add(&format!("/{file}")).expect(&file);
                         }
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
index 442638d3203..94b03b1b138 100644
--- a/src/bootstrap/src/core/build_steps/llvm.rs
+++ b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -16,6 +16,7 @@ use std::sync::OnceLock;
 use std::{env, io};
 
 use build_helper::ci::CiEnv;
+use build_helper::git::get_closest_merge_commit;
 
 use crate::core::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::core::config::{Config, TargetSelection};
@@ -153,10 +154,9 @@ pub fn prebuilt_llvm_config(builder: &Builder<'_>, target: TargetSelection) -> L
 /// This retrieves the LLVM sha we *want* to use, according to git history.
 pub(crate) fn detect_llvm_sha(config: &Config, is_git: bool) -> String {
     let llvm_sha = if is_git {
-        helpers::get_closest_merge_base_commit(
+        get_closest_merge_commit(
             Some(&config.src),
             &config.git_config(),
-            &config.stage0_metadata.config.git_merge_commit_email,
             &[
                 config.src.join("src/llvm-project"),
                 config.src.join("src/bootstrap/download-ci-llvm-stamp"),
diff --git a/src/bootstrap/src/core/build_steps/suggest.rs b/src/bootstrap/src/core/build_steps/suggest.rs
index 8aaffab514d..ba9b1b2fc33 100644
--- a/src/bootstrap/src/core/build_steps/suggest.rs
+++ b/src/bootstrap/src/core/build_steps/suggest.rs
@@ -17,6 +17,7 @@ pub fn suggest(builder: &Builder<'_>, run: bool) {
         .tool_cmd(Tool::SuggestTests)
         .env("SUGGEST_TESTS_GIT_REPOSITORY", git_config.git_repository)
         .env("SUGGEST_TESTS_NIGHTLY_BRANCH", git_config.nightly_branch)
+        .env("SUGGEST_TESTS_MERGE_COMMIT_EMAIL", git_config.git_merge_commit_email)
         .run_capture_stdout(builder)
         .stdout();
 
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 83f65615c8d..a7e9352bb1c 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -2098,6 +2098,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         let git_config = builder.config.git_config();
         cmd.arg("--git-repository").arg(git_config.git_repository);
         cmd.arg("--nightly-branch").arg(git_config.nightly_branch);
+        cmd.arg("--git-merge-commit-email").arg(git_config.git_merge_commit_email);
         cmd.force_coloring_in_ci();
 
         #[cfg(feature = "build-metrics")]
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index 3c2d791c209..a437f829ba5 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -1,6 +1,8 @@
 use std::path::PathBuf;
 use std::{env, fs};
 
+use build_helper::git::get_closest_merge_commit;
+
 use crate::core::build_steps::compile;
 use crate::core::build_steps::toolstate::ToolState;
 use crate::core::builder;
@@ -8,7 +10,7 @@ use crate::core::builder::{Builder, Cargo as CargoCommand, RunConfig, ShouldRun,
 use crate::core::config::TargetSelection;
 use crate::utils::channel::GitInfo;
 use crate::utils::exec::{command, BootstrapCommand};
-use crate::utils::helpers::{add_dylib_path, exe, get_closest_merge_base_commit, git, t};
+use crate::utils::helpers::{add_dylib_path, exe, git, t};
 use crate::{gha, Compiler, Kind, Mode};
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
@@ -576,10 +578,9 @@ impl Step for Rustdoc {
             && target_compiler.stage > 0
             && builder.rust_info().is_managed_git_subrepository()
         {
-            let commit = get_closest_merge_base_commit(
+            let commit = get_closest_merge_commit(
                 Some(&builder.config.src),
                 &builder.config.git_config(),
-                &builder.config.stage0_metadata.config.git_merge_commit_email,
                 &[],
             )
             .unwrap();
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index f509712730d..9271e809853 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -14,7 +14,7 @@ use std::sync::OnceLock;
 use std::{cmp, env, fs};
 
 use build_helper::exit;
-use build_helper::git::{output_result, GitConfig};
+use build_helper::git::{get_closest_merge_commit, output_result, GitConfig};
 use serde::{Deserialize, Deserializer};
 use serde_derive::Deserialize;
 
@@ -24,7 +24,7 @@ pub use crate::core::config::flags::Subcommand;
 use crate::core::config::flags::{Color, Flags, Warnings};
 use crate::utils::cache::{Interned, INTERNER};
 use crate::utils::channel::{self, GitInfo};
-use crate::utils::helpers::{self, exe, get_closest_merge_base_commit, output, t};
+use crate::utils::helpers::{self, exe, output, t};
 
 macro_rules! check_ci_llvm {
     ($name:expr) => {
@@ -2512,6 +2512,7 @@ impl Config {
         GitConfig {
             git_repository: &self.stage0_metadata.config.git_repository,
             nightly_branch: &self.stage0_metadata.config.nightly_branch,
+            git_merge_commit_email: &self.stage0_metadata.config.git_merge_commit_email,
         }
     }
 
@@ -2688,13 +2689,7 @@ impl Config {
 
         // Look for a version to compare to based on the current commit.
         // Only commits merged by bors will have CI artifacts.
-        let commit = get_closest_merge_base_commit(
-            Some(&self.src),
-            &self.git_config(),
-            &self.stage0_metadata.config.git_merge_commit_email,
-            &[],
-        )
-        .unwrap();
+        let commit = get_closest_merge_commit(Some(&self.src), &self.git_config(), &[]).unwrap();
         if commit.is_empty() {
             println!("ERROR: could not find commit hash for downloading rustc");
             println!("HELP: maybe your repository history is too shallow?");
@@ -2786,13 +2781,7 @@ impl Config {
     ) -> Option<String> {
         // Look for a version to compare to based on the current commit.
         // Only commits merged by bors will have CI artifacts.
-        let commit = get_closest_merge_base_commit(
-            Some(&self.src),
-            &self.git_config(),
-            &self.stage0_metadata.config.git_merge_commit_email,
-            &[],
-        )
-        .unwrap();
+        let commit = get_closest_merge_commit(Some(&self.src), &self.git_config(), &[]).unwrap();
         if commit.is_empty() {
             println!("error: could not find commit hash for downloading components from CI");
             println!("help: maybe your repository history is too shallow?");
diff --git a/src/bootstrap/src/utils/helpers.rs b/src/bootstrap/src/utils/helpers.rs
index a856c99ff55..beb3c5fb098 100644
--- a/src/bootstrap/src/utils/helpers.rs
+++ b/src/bootstrap/src/utils/helpers.rs
@@ -10,7 +10,6 @@ use std::sync::OnceLock;
 use std::time::{Instant, SystemTime, UNIX_EPOCH};
 use std::{env, fs, io, str};
 
-use build_helper::git::{get_git_merge_base, output_result, GitConfig};
 use build_helper::util::fail;
 
 use crate::core::builder::Builder;
@@ -523,28 +522,6 @@ pub fn git(source_dir: Option<&Path>) -> BootstrapCommand {
     git
 }
 
-/// Returns the closest commit available from upstream for the given `author` and `target_paths`.
-///
-/// If it fails to find the commit from upstream using `git merge-base`, fallbacks to HEAD.
-pub fn get_closest_merge_base_commit(
-    source_dir: Option<&Path>,
-    config: &GitConfig<'_>,
-    author: &str,
-    target_paths: &[PathBuf],
-) -> Result<String, String> {
-    let mut git = git(source_dir);
-
-    let merge_base = get_git_merge_base(config, source_dir).unwrap_or_else(|_| "HEAD".into());
-
-    git.args(["rev-list", &format!("--author={author}"), "-n1", "--first-parent", &merge_base]);
-
-    if !target_paths.is_empty() {
-        git.arg("--").args(target_paths);
-    }
-
-    Ok(output_result(git.as_command_mut())?.trim().to_owned())
-}
-
 /// Sets the file times for a given file at `path`.
 pub fn set_file_times<P: AsRef<Path>>(path: P, times: fs::FileTimes) -> io::Result<()> {
     // Windows requires file to be writable to modify file times. But on Linux CI the file does not
diff --git a/src/tools/build_helper/src/git.rs b/src/tools/build_helper/src/git.rs
index cc48a8964a3..15d863caf0c 100644
--- a/src/tools/build_helper/src/git.rs
+++ b/src/tools/build_helper/src/git.rs
@@ -1,9 +1,10 @@
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 
 pub struct GitConfig<'a> {
     pub git_repository: &'a str,
     pub nightly_branch: &'a str,
+    pub git_merge_commit_email: &'a str,
 }
 
 /// Runs a command and returns the output
@@ -95,7 +96,11 @@ pub fn updated_master_branch(
     Err("Cannot find any suitable upstream master branch".to_owned())
 }
 
-pub fn get_git_merge_base(
+/// Finds the nearest merge commit by comparing the local `HEAD` with the upstream branch's state.
+/// To work correctly, the upstream remote must be properly configured using `git remote add <name> <url>`.
+/// In most cases `get_closest_merge_commit` is the function you are looking for as it doesn't require remote
+/// to be configured.
+fn git_upstream_merge_base(
     config: &GitConfig<'_>,
     git_dir: Option<&Path>,
 ) -> Result<String, String> {
@@ -107,6 +112,38 @@ pub fn get_git_merge_base(
     Ok(output_result(git.arg("merge-base").arg(&updated_master).arg("HEAD"))?.trim().to_owned())
 }
 
+/// Searches for the nearest merge commit in the repository that also exists upstream.
+///
+/// If it fails to find the upstream remote, it then looks for the most recent commit made
+/// by the merge bot by matching the author's email address with the merge bot's email.
+pub fn get_closest_merge_commit(
+    git_dir: Option<&Path>,
+    config: &GitConfig<'_>,
+    target_paths: &[PathBuf],
+) -> Result<String, String> {
+    let mut git = Command::new("git");
+
+    if let Some(git_dir) = git_dir {
+        git.current_dir(git_dir);
+    }
+
+    let merge_base = git_upstream_merge_base(config, git_dir).unwrap_or_else(|_| "HEAD".into());
+
+    git.args([
+        "rev-list",
+        &format!("--author={}", config.git_merge_commit_email),
+        "-n1",
+        "--first-parent",
+        &merge_base,
+    ]);
+
+    if !target_paths.is_empty() {
+        git.arg("--").args(target_paths);
+    }
+
+    Ok(output_result(&mut git)?.trim().to_owned())
+}
+
 /// Returns the files that have been modified in the current branch compared to the master branch.
 /// The `extensions` parameter can be used to filter the files by their extension.
 /// Does not include removed files.
@@ -116,7 +153,7 @@ pub fn get_git_modified_files(
     git_dir: Option<&Path>,
     extensions: &[&str],
 ) -> Result<Option<Vec<String>>, String> {
-    let merge_base = get_git_merge_base(config, git_dir)?;
+    let merge_base = get_closest_merge_commit(git_dir, config, &[])?;
 
     let mut git = Command::new("git");
     if let Some(git_dir) = git_dir {
diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 773d795f75a..5c18179b6fe 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -384,6 +384,7 @@ pub struct Config {
     // Needed both to construct build_helper::git::GitConfig
     pub git_repository: String,
     pub nightly_branch: String,
+    pub git_merge_commit_email: String,
 
     /// True if the profiler runtime is enabled for this target.
     /// Used by the "needs-profiler-support" header in test files.
@@ -461,7 +462,11 @@ impl Config {
     }
 
     pub fn git_config(&self) -> GitConfig<'_> {
-        GitConfig { git_repository: &self.git_repository, nightly_branch: &self.nightly_branch }
+        GitConfig {
+            git_repository: &self.git_repository,
+            nightly_branch: &self.nightly_branch,
+            git_merge_commit_email: &self.git_merge_commit_email,
+        }
     }
 }
 
diff --git a/src/tools/compiletest/src/header/tests.rs b/src/tools/compiletest/src/header/tests.rs
index 29e11e77f1c..3a9a7eb9118 100644
--- a/src/tools/compiletest/src/header/tests.rs
+++ b/src/tools/compiletest/src/header/tests.rs
@@ -148,6 +148,7 @@ impl ConfigBuilder {
             self.target.as_deref().unwrap_or("x86_64-unknown-linux-gnu"),
             "--git-repository=",
             "--nightly-branch=",
+            "--git-merge-commit-email=",
         ];
         let mut args: Vec<String> = args.iter().map(ToString::to_string).collect();
 
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index 33687a3dad3..5fe73a0e297 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -163,7 +163,13 @@ pub fn parse_config(args: Vec<String>) -> Config {
         )
         .optopt("", "edition", "default Rust edition", "EDITION")
         .reqopt("", "git-repository", "name of the git repository", "ORG/REPO")
-        .reqopt("", "nightly-branch", "name of the git branch for nightly", "BRANCH");
+        .reqopt("", "nightly-branch", "name of the git branch for nightly", "BRANCH")
+        .reqopt(
+            "",
+            "git-merge-commit-email",
+            "email address used for finding merge commits",
+            "EMAIL",
+        );
 
     let (argv0, args_) = args.split_first().unwrap();
     if args.len() == 1 || args[1] == "-h" || args[1] == "--help" {
@@ -346,6 +352,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
 
         git_repository: matches.opt_str("git-repository").unwrap(),
         nightly_branch: matches.opt_str("nightly-branch").unwrap(),
+        git_merge_commit_email: matches.opt_str("git-merge-commit-email").unwrap(),
 
         profiler_support: matches.opt_present("profiler-support"),
     }
diff --git a/src/tools/suggest-tests/src/main.rs b/src/tools/suggest-tests/src/main.rs
index 8e3625c2449..6f09bddcf60 100644
--- a/src/tools/suggest-tests/src/main.rs
+++ b/src/tools/suggest-tests/src/main.rs
@@ -8,6 +8,7 @@ fn main() -> ExitCode {
         &GitConfig {
             git_repository: &env("SUGGEST_TESTS_GIT_REPOSITORY"),
             nightly_branch: &env("SUGGEST_TESTS_NIGHTLY_BRANCH"),
+            git_merge_commit_email: &env("SUGGEST_TESTS_MERGE_COMMIT_EMAIL"),
         },
         None,
         &Vec::new(),