Rollup merge of #113780 - dtolnay:printkindpath, r=b-naber

Support `--print KIND=PATH` command line syntax

As is already done for `--emit KIND=PATH` and `-L KIND=PATH`.

In the discussion of #110785, it was pointed out that `--print KIND=PATH` is nicer than trying to apply the single global `-o` path to `--print`'s output, because in general there can be multiple print requests within a single rustc invocation, and anyway `-o` would already be used for a different meaning in the case of `link-args` and `native-static-libs`.

I am interested in using `--print cfg=PATH` in Buck2. Currently Buck2 works around the lack of support for `--print KIND=PATH` by [indirecting through a Python wrapper script](d43cf3a51a/prelude/rust/tools/get_rustc_cfg.py) to redirect rustc's stdout into the location dictated by the build system.

From skimming Cargo's usages of `--print`, it definitely seems like it would benefit from `--print KIND=PATH` too. Currently it is working around the lack of this by inserting `--crate-name=___ --print=crate-name` so that it can look for a line containing `___` as a delimiter between the 2 other `--print` informations it actually cares about. This is commented as a "HACK" and "abuse". 31eda6f7c3/src/cargo/core/compiler/build_context/target_info.rs (L242) (FYI `@weihanglo` as you dealt with this recently in https://github.com/rust-lang/cargo/pull/11633.)

Mentioning reviewers active in #110785: `@fee1-dead` `@jyn514` `@bjorn3`

compiler/rustc_driver_impl/src/lib.rs

@@ -37,9 +37,7 @@ use rustc_interface::{interface, Queries};
 use rustc_lint::LintStore;
 use rustc_metadata::locator;
 use rustc_session::config::{nightly_options, CG_OPTIONS, Z_OPTIONS};
-use rustc_session::config::{
-    ErrorOutputType, Input, OutFileName, OutputType, PrintRequest, TrimmedDefPaths,
-};
+use rustc_session::config::{ErrorOutputType, Input, OutFileName, OutputType, TrimmedDefPaths};
 use rustc_session::cstore::MetadataLoader;
 use rustc_session::getopts::{self, Matches};
 use rustc_session::lint::{Lint, LintId};
@@ -53,6 +51,7 @@ use std::cmp::max;
 use std::collections::BTreeMap;
 use std::env;
 use std::ffi::OsString;
+use std::fmt::Write as _;
 use std::fs;
 use std::io::{self, IsTerminal, Read, Write};
 use std::panic::{self, catch_unwind};
@@ -72,6 +71,11 @@ macro do_not_use_print($($t:tt)*) {
     )
 }
 
+#[allow(unused_macros)]
+macro do_not_use_safe_print($($t:tt)*) {
+    std::compile_error!("Don't use `safe_print` or `safe_println` here, use `println_info` instead")
+}
+
 // This import blocks the use of panicking `print` and `println` in all the code
 // below. Please use `safe_print` and `safe_println` to avoid ICE when
 // encountering an I/O error during print.
@@ -720,10 +724,17 @@ fn print_crate_info(
     sess: &Session,
     parse_attrs: bool,
 ) -> Compilation {
-    use rustc_session::config::PrintRequest::*;
+    use rustc_session::config::PrintKind::*;
+
+    // This import prevents the following code from using the printing macros
+    // used by the rest of the module. Within this function, we only write to
+    // the output specified by `sess.io.output_file`.
+    #[allow(unused_imports)]
+    use {do_not_use_safe_print as safe_print, do_not_use_safe_print as safe_println};
+
     // NativeStaticLibs and LinkArgs are special - printed during linking
     // (empty iterator returns true)
-    if sess.opts.prints.iter().all(|&p| p == NativeStaticLibs || p == LinkArgs) {
+    if sess.opts.prints.iter().all(|p| p.kind == NativeStaticLibs || p.kind == LinkArgs) {
         return Compilation::Continue;
     }
 
@@ -739,17 +750,23 @@ fn print_crate_info(
     } else {
         None
     };
+
     for req in &sess.opts.prints {
-        match *req {
+        let mut crate_info = String::new();
+        macro println_info($($arg:tt)*) {
+            crate_info.write_fmt(format_args!("{}\n", format_args!($($arg)*))).unwrap()
+        }
+
+        match req.kind {
             TargetList => {
                 let mut targets = rustc_target::spec::TARGETS.to_vec();
                 targets.sort_unstable();
-                safe_println!("{}", targets.join("\n"));
+                println_info!("{}", targets.join("\n"));
             }
-            Sysroot => safe_println!("{}", sess.sysroot.display()),
-            TargetLibdir => safe_println!("{}", sess.target_tlib_path.dir.display()),
+            Sysroot => println_info!("{}", sess.sysroot.display()),
+            TargetLibdir => println_info!("{}", sess.target_tlib_path.dir.display()),
             TargetSpec => {
-                safe_println!("{}", serde_json::to_string_pretty(&sess.target.to_json()).unwrap());
+                println_info!("{}", serde_json::to_string_pretty(&sess.target.to_json()).unwrap());
             }
             AllTargetSpecs => {
                 let mut targets = BTreeMap::new();
@@ -758,26 +775,30 @@ fn print_crate_info(
                     let target = Target::expect_builtin(&triple);
                     targets.insert(name, target.to_json());
                 }
-                safe_println!("{}", serde_json::to_string_pretty(&targets).unwrap());
+                println_info!("{}", serde_json::to_string_pretty(&targets).unwrap());
             }
-            FileNames | CrateName => {
+            FileNames => {
                 let Some(attrs) = attrs.as_ref() else {
                     // no crate attributes, print out an error and exit
                     return Compilation::Continue;
                 };
                 let t_outputs = rustc_interface::util::build_output_filenames(attrs, sess);
                 let id = rustc_session::output::find_crate_name(sess, attrs);
-                if *req == PrintRequest::CrateName {
-                    safe_println!("{id}");
-                    continue;
-                }
                 let crate_types = collect_crate_types(sess, attrs);
                 for &style in &crate_types {
                     let fname =
                         rustc_session::output::filename_for_input(sess, style, id, &t_outputs);
-                    safe_println!("{}", fname.as_path().file_name().unwrap().to_string_lossy());
+                    println_info!("{}", fname.as_path().file_name().unwrap().to_string_lossy());
                 }
             }
+            CrateName => {
+                let Some(attrs) = attrs.as_ref() else {
+                    // no crate attributes, print out an error and exit
+                    return Compilation::Continue;
+                };
+                let id = rustc_session::output::find_crate_name(sess, attrs);
+                println_info!("{id}");
+            }
             Cfg => {
                 let mut cfgs = sess
                     .parse_sess
@@ -809,13 +830,13 @@ fn print_crate_info(
 
                 cfgs.sort();
                 for cfg in cfgs {
-                    safe_println!("{cfg}");
+                    println_info!("{cfg}");
                 }
             }
             CallingConventions => {
                 let mut calling_conventions = rustc_target::spec::abi::all_names();
                 calling_conventions.sort_unstable();
-                safe_println!("{}", calling_conventions.join("\n"));
+                println_info!("{}", calling_conventions.join("\n"));
             }
             RelocationModels
             | CodeModels
@@ -823,7 +844,7 @@ fn print_crate_info(
             | TargetCPUs
             | StackProtectorStrategies
             | TargetFeatures => {
-                codegen_backend.print(*req, sess);
+                codegen_backend.print(req, &mut crate_info, sess);
             }
             // Any output here interferes with Cargo's parsing of other printed output
             NativeStaticLibs => {}
@@ -833,7 +854,7 @@ fn print_crate_info(
 
                 for split in &[Off, Packed, Unpacked] {
                     if sess.target.options.supported_split_debuginfo.contains(split) {
-                        safe_println!("{split}");
+                        println_info!("{split}");
                     }
                 }
             }
@@ -841,7 +862,7 @@ fn print_crate_info(
                 use rustc_target::spec::current_apple_deployment_target;
 
                 if sess.target.is_like_osx {
-                    safe_println!(
+                    println_info!(
                         "deployment_target={}",
                         current_apple_deployment_target(&sess.target)
                             .expect("unknown Apple target OS")
@@ -852,6 +873,8 @@ fn print_crate_info(
                 }
             }
         }
+
+        req.out.overwrite(&crate_info, sess);
     }
     Compilation::Stop
 }

compiler/rustc_driver_impl/src/pretty.rs

@@ -1,6 +1,5 @@
 //! The various pretty-printing routines.
 
-use crate::session_diagnostics::UnprettyDumpFail;
 use rustc_ast as ast;
 use rustc_ast_pretty::pprust;
 use rustc_errors::ErrorGuaranteed;
@@ -358,17 +357,7 @@ fn get_source(sess: &Session) -> (String, FileName) {
 }
 
 fn write_or_print(out: &str, sess: &Session) {
-    match &sess.io.output_file {
-        None | Some(OutFileName::Stdout) => print!("{out}"),
-        Some(OutFileName::Real(p)) => {
-            if let Err(e) = std::fs::write(p, out) {
-                sess.emit_fatal(UnprettyDumpFail {
-                    path: p.display().to_string(),
-                    err: e.to_string(),
-                });
-            }
-        }
-    }
+    sess.io.output_file.as_ref().unwrap_or(&OutFileName::Stdout).overwrite(out, sess);
 }
 
 pub fn print_after_parsing(sess: &Session, krate: &ast::Crate, ppm: PpMode) {

compiler/rustc_driver_impl/src/session_diagnostics.rs

@@ -32,13 +32,6 @@ pub(crate) struct RLinkRustcVersionMismatch<'a> {
 #[diag(driver_impl_rlink_no_a_file)]
 pub(crate) struct RlinkNotAFile;
 
-#[derive(Diagnostic)]
-#[diag(driver_impl_unpretty_dump_fail)]
-pub(crate) struct UnprettyDumpFail {
-    pub path: String,
-    pub err: String,
-}
-
 #[derive(Diagnostic)]
 #[diag(driver_impl_ice)]
 pub(crate) struct Ice;