run-make: arm command wrappers with drop bombs

Cargo.lock

@@ -3452,7 +3452,7 @@ dependencies = [
 
 [[package]]
 name = "run_make_support"
-version = "0.0.0"
+version = "0.1.0"
 dependencies = [
  "gimli 0.28.1",
  "object 0.34.0",

src/tools/run-make-support/CHANGELOG.md

@@ -0,0 +1,67 @@
+# Changelog
+
+All notable changes to the `run_make_support` library should be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/) and the support
+library should adhere to [Semantic Versioning](https://semver.org/spec/v2.0.0.html) even if it's
+not intended for public consumption (it's moreso to help internally, to help test writers track
+changes to the support library).
+
+This support library will probably never reach 1.0. Please bump the minor version in `Cargo.toml` if
+you make any breaking changes or other significant changes, or bump the patch version for bug fixes.
+
+## [0.1.0] - 2024-06-09
+
+### Changed
+
+- Use *drop bombs* to enforce that commands are executed; a command invocation will panic if it is
+  constructed but never executed. Execution methods `Command::{run, run_fail}` will defuse the drop
+  bomb.
+- Added `Command` helpers that forward to `std::process::Command` counterparts.
+
+### Removed
+
+- The `env_var` method which was incorrectly named and is `env_clear` underneath and is a footgun
+  from `impl_common_helpers`. For example, removing `TMPDIR` on Unix and `TMP`/`TEMP` breaks
+  `std::env::temp_dir` and wrecks anything using that, such as rustc's codgen.
+- Removed `Deref`/`DerefMut` for `run_make_support::Command` -> `std::process::Command` because it
+  causes a method chain like `htmldocck().arg().run()` to fail, because `arg()` resolves to
+  `std::process::Command` which also returns a `&mut std::process::Command`, causing the `run()` to
+  be not found.
+
+## [0.0.0] - 2024-06-09
+
+Consider this version to contain all changes made to the support library before we started to track
+changes in this changelog.
+
+### Added
+
+- Custom command wrappers around `std::process::Command` (`run_make_support::Command`) and custom
+  wrapper around `std::process::Output` (`CompletedProcess`) to make it more convenient to work with
+  commands and their output, and help avoid forgetting to check for exit status.
+    - `Command`: `set_stdin`, `run`, `run_fail`.
+    - `CompletedProcess`: `std{err,out}_utf8`, `status`, `assert_std{err,out}_{equals, contains,
+      not_contains}`, `assert_exit_code`.
+- `impl_common_helpers` macro to avoid repeating adding common convenience methods, including:
+    - Environment manipulation methods: `env`, `env_remove`
+    - Command argument providers: `arg`, `args`
+    - Common invocation inspection (of the command invocation up until `inspect` is called):
+      `inspect`
+    - Execution methods: `run` (for commands expected to succeed execution, exit status `0`) and
+      `run_fail` (for commands expected to fail execution, exit status non-zero).
+- Command wrappers around: `rustc`, `clang`, `cc`, `rustc`, `rustdoc`, `llvm-readobj`.
+- Thin helpers to construct `python` and `htmldocck` commands.
+- `run` and `run_fail` (like `Command::{run, run_fail}`) for running binaries, which sets suitable
+  env vars (like `LD_LIB_PATH` or equivalent, `TARGET_RPATH_ENV`, `PATH` on Windows).
+- Pseudo command `diff` which has similar functionality as the cli util but not the same API.
+- Convenience panic-on-fail helpers `env_var`, `env_var_os`, `cwd` for their `std::env` conterparts.
+- Convenience panic-on-fail helpers for reading respective env vars: `target`, `source_root`.
+- Platform check helpers: `is_windows`, `is_msvc`, `cygpath_windows`, `uname`.
+- fs helpers: `copy_dir_all`.
+- `recursive_diff` helper.
+- Generic `assert_not_contains` helper.
+- Scoped run-with-teardown helper `run_in_tmpdir` which is designed to run commands in a temporary
+  directory that is cleared when closure returns.
+- Helpers for constructing the name of binaries and libraries: `rust_lib_name`, `static_lib_name`,
+  `bin_name`, `dynamic_lib_name`.
+- Re-export libraries: `gimli`, `object`, `regex`, `wasmparsmer`.

src/tools/run-make-support/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "run_make_support"
-version = "0.0.0"
+version = "0.1.0"
 edition = "2021"
 
 [dependencies]

src/tools/run-make-support/src/cc.rs

@@ -7,6 +7,7 @@ use crate::{bin_name, cygpath_windows, env_var, is_msvc, is_windows, uname};
 ///
 /// WARNING: This means that what flags are accepted by the underlying C compiler is
 /// platform- AND compiler-specific. Consult the relevant docs for `gcc`, `clang` and `mvsc`.
+#[track_caller]
 pub fn cc() -> Cc {
     Cc::new()
 }
@@ -25,6 +26,7 @@ impl Cc {
     ///
     /// WARNING: This means that what flags are accepted by the underlying C compile is
     /// platform- AND compiler-specific. Consult the relevant docs for `gcc`, `clang` and `mvsc`.
+    #[track_caller]
     pub fn new() -> Self {
         let compiler = env_var("CC");
 
@@ -84,11 +86,6 @@ impl Cc {
         self.cmd.arg(path.as_ref());
         self
     }
-
-    /// Get the [`Output`][::std::process::Output] of the finished process.
-    pub fn command_output(&mut self) -> ::std::process::Output {
-        self.cmd.output().expect("failed to get output of finished process")
-    }
 }
 
 /// `EXTRACFLAGS`

src/tools/run-make-support/src/clang.rs

@@ -4,6 +4,7 @@ use crate::command::Command;
 use crate::{bin_name, env_var};
 
 /// Construct a new `clang` invocation. `clang` is not always available for all targets.
+#[track_caller]
 pub fn clang() -> Clang {
     Clang::new()
 }
@@ -18,6 +19,7 @@ crate::impl_common_helpers!(Clang);
 
 impl Clang {
     /// Construct a new `clang` invocation. `clang` is not always available for all targets.
+    #[track_caller]
     pub fn new() -> Self {
         let clang = env_var("CLANG");
         let cmd = Command::new(clang);

src/tools/run-make-support/src/command.rs

@@ -1,55 +1,124 @@
-use crate::{assert_not_contains, handle_failed_output};
+use std::ffi;
 use std::ffi::OsStr;
 use std::io::Write;
-use std::ops::{Deref, DerefMut};
+use std::panic;
+use std::path::Path;
 use std::process::{Command as StdCommand, ExitStatus, Output, Stdio};
 
-/// This is a custom command wrapper that simplifies working with commands
-/// and makes it easier to ensure that we check the exit status of executed
-/// processes.
+use crate::drop_bomb::DropBomb;
+use crate::{assert_not_contains, handle_failed_output};
+
+/// This is a custom command wrapper that simplifies working with commands and makes it easier to
+/// ensure that we check the exit status of executed processes.
+///
+/// # A [`Command`] must be executed
+///
+/// A [`Command`] is armed by a [`DropBomb`] on construction to enforce that it will be executed. If
+/// a [`Command`] is constructed but never executed, the drop bomb will explode and cause the test
+/// to panic. Execution methods [`run`] and [`run_fail`] will defuse the drop bomb. A test
+/// containing constructed but never executed commands is dangerous because it can give a false
+/// sense of confidence.
+///
+/// [`run`]: Self::run
+/// [`run_fail`]: Self::run_fail
 #[derive(Debug)]
 pub struct Command {
     cmd: StdCommand,
     stdin: Option<Box<[u8]>>,
+    drop_bomb: DropBomb,
 }
 
 impl Command {
-    pub fn new<S: AsRef<OsStr>>(program: S) -> Self {
-        Self { cmd: StdCommand::new(program), stdin: None }
+    #[track_caller]
+    pub fn new<P: AsRef<OsStr>>(program: P) -> Self {
+        let program = program.as_ref();
+        Self { cmd: StdCommand::new(program), stdin: None, drop_bomb: DropBomb::arm(program) }
     }
 
     pub fn set_stdin(&mut self, stdin: Box<[u8]>) {
         self.stdin = Some(stdin);
     }
 
+    /// Specify an environment variable.
+    pub fn env<K, V>(&mut self, key: K, value: V) -> &mut Self
+    where
+        K: AsRef<ffi::OsStr>,
+        V: AsRef<ffi::OsStr>,
+    {
+        self.cmd.env(key, value);
+        self
+    }
+
+    /// Remove an environmental variable.
+    pub fn env_remove<K>(&mut self, key: K) -> &mut Self
+    where
+        K: AsRef<ffi::OsStr>,
+    {
+        self.cmd.env_remove(key);
+        self
+    }
+
+    /// Generic command argument provider. Prefer specific helper methods if possible.
+    /// Note that for some executables, arguments might be platform specific. For C/C++
+    /// compilers, arguments might be platform *and* compiler specific.
+    pub fn arg<S>(&mut self, arg: S) -> &mut Self
+    where
+        S: AsRef<ffi::OsStr>,
+    {
+        self.cmd.arg(arg);
+        self
+    }
+
+    /// Generic command arguments provider. Prefer specific helper methods if possible.
+    /// Note that for some executables, arguments might be platform specific. For C/C++
+    /// compilers, arguments might be platform *and* compiler specific.
+    pub fn args<S>(&mut self, args: &[S]) -> &mut Self
+    where
+        S: AsRef<ffi::OsStr>,
+    {
+        self.cmd.args(args);
+        self
+    }
+
+    /// Inspect what the underlying [`std::process::Command`] is up to the
+    /// current construction.
+    pub fn inspect<I>(&mut self, inspector: I) -> &mut Self
+    where
+        I: FnOnce(&StdCommand),
+    {
+        inspector(&self.cmd);
+        self
+    }
+
+    /// Set the path where the command will be run.
+    pub fn current_dir<P: AsRef<Path>>(&mut self, path: P) -> &mut Self {
+        self.cmd.current_dir(path);
+        self
+    }
+
     /// Run the constructed command and assert that it is successfully run.
     #[track_caller]
     pub fn run(&mut self) -> CompletedProcess {
-        let caller_location = std::panic::Location::caller();
-        let caller_line_number = caller_location.line();
-
         let output = self.command_output();
         if !output.status().success() {
-            handle_failed_output(&self, output, caller_line_number);
+            handle_failed_output(&self, output, panic::Location::caller().line());
         }
         output
     }
 
     /// Run the constructed command and assert that it does not successfully run.
     #[track_caller]
     pub fn run_fail(&mut self) -> CompletedProcess {
-        let caller_location = std::panic::Location::caller();
-        let caller_line_number = caller_location.line();
-
         let output = self.command_output();
         if output.status().success() {
-            handle_failed_output(&self, output, caller_line_number);
+            handle_failed_output(&self, output, panic::Location::caller().line());
         }
         output
     }
 
     #[track_caller]
-    pub(crate) fn command_output(&mut self) -> CompletedProcess {
+    fn command_output(&mut self) -> CompletedProcess {
+        self.drop_bomb.defuse();
         // let's make sure we piped all the input and outputs
         self.cmd.stdin(Stdio::piped());
         self.cmd.stdout(Stdio::piped());
@@ -71,20 +140,6 @@ impl Command {
     }
 }
 
-impl Deref for Command {
-    type Target = StdCommand;
-
-    fn deref(&self) -> &Self::Target {
-        &self.cmd
-    }
-}
-
-impl DerefMut for Command {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.cmd
-    }
-}
-
 /// Represents the result of an executed process.
 /// The various `assert_` helper methods should preferably be used for
 /// checking the contents of stdout/stderr.

src/tools/run-make-support/src/diff/mod.rs

@@ -2,9 +2,12 @@ use regex::Regex;
 use similar::TextDiff;
 use std::path::Path;
 
+use crate::drop_bomb::DropBomb;
+
 #[cfg(test)]
 mod tests;
 
+#[track_caller]
 pub fn diff() -> Diff {
     Diff::new()
 }
@@ -16,17 +19,20 @@ pub struct Diff {
     actual: Option<String>,
     actual_name: Option<String>,
     normalizers: Vec<(String, String)>,
+    drop_bomb: DropBomb,
 }
 
 impl Diff {
     /// Construct a bare `diff` invocation.
+    #[track_caller]
     pub fn new() -> Self {
         Self {
             expected: None,
             expected_name: None,
             actual: None,
             actual_name: None,
             normalizers: Vec::new(),
+            drop_bomb: DropBomb::arm("diff"),
         }
     }
 
@@ -79,9 +85,9 @@ impl Diff {
         self
     }
 
-    /// Executes the diff process, prints any differences to the standard error.
     #[track_caller]
-    pub fn run(&self) {
+    pub fn run(&mut self) {
+        self.drop_bomb.defuse();
         let expected = self.expected.as_ref().expect("expected text not set");
         let mut actual = self.actual.as_ref().expect("actual text not set").to_string();
         let expected_name = self.expected_name.as_ref().unwrap();

src/tools/run-make-support/src/drop_bomb/mod.rs

@@ -0,0 +1,50 @@
+//! This module implements "drop bombs" intended for use by command wrappers to ensure that the
+//! constructed commands are *eventually* executed. This is exactly like `rustc_errors::Diag` where
+//! we force every `Diag` to be consumed or we emit a bug, but we panic instead.
+//!
+//! This is adapted from <https://docs.rs/drop_bomb/latest/drop_bomb/> and simplified for our
+//! purposes.
+
+use std::ffi::{OsStr, OsString};
+use std::panic;
+
+#[cfg(test)]
+mod tests;
+
+#[derive(Debug)]
+pub(crate) struct DropBomb {
+    command: OsString,
+    defused: bool,
+    armed_line: u32,
+}
+
+impl DropBomb {
+    /// Arm a [`DropBomb`]. If the value is dropped without being [`defused`][Self::defused], then
+    /// it will panic. It is expected that the command wrapper uses `#[track_caller]` to help
+    /// propagate the caller info from rmake.rs.
+    #[track_caller]
+    pub(crate) fn arm<S: AsRef<OsStr>>(command: S) -> DropBomb {
+        DropBomb {
+            command: command.as_ref().into(),
+            defused: false,
+            armed_line: panic::Location::caller().line(),
+        }
+    }
+
+    /// Defuse the [`DropBomb`]. This will prevent the drop bomb from panicking when dropped.
+    pub(crate) fn defuse(&mut self) {
+        self.defused = true;
+    }
+}
+
+impl Drop for DropBomb {
+    fn drop(&mut self) {
+        if !self.defused && !std::thread::panicking() {
+            panic!(
+                "command constructed but not executed at line {}: `{}`",
+                self.armed_line,
+                self.command.to_string_lossy()
+            )
+        }
+    }
+}