Auto merge of #8236 - ehuss:no-panic-output, r=alexcrichton

Ignore broken console output in some situations.

If stdout or stderr is closed while Cargo is running, Cargo would panic in some situations (usually with EPIPE). For example, `cargo install --list | grep -q cargo-fuzz`, where `grep` will close stdout once it gets a match. This changes it so that Cargo will ignore output errors in most situations. Failure to output a regular build message still results in an error, which follows the behavior of some tools like `make`.

All output, including stdout, now goes through `Shell`.

Closes #5234

src/bin/cargo/cli.rs

@@ -1,5 +1,5 @@
 use cargo::core::features;
-use cargo::{self, CliResult, Config};
+use cargo::{self, drop_print, drop_println, CliResult, Config};
 use clap::{AppSettings, Arg, ArgMatches};
 
 use super::commands;
@@ -25,7 +25,8 @@ pub fn main(config: &mut Config) -> CliResult {
     };
 
     if args.value_of("unstable-features") == Some("help") {
-        println!(
+        drop_println!(
+            config,
             "
 Available unstable (nightly-only) flags:
 
@@ -40,15 +41,17 @@ Available unstable (nightly-only) flags:
 Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
         );
         if !features::nightly_features_allowed() {
-            println!(
+            drop_println!(
+                config,
                 "\nUnstable flags are only available on the nightly channel \
                  of Cargo, but this is the `{}` channel.\n\
                  {}",
                 features::channel(),
                 features::SEE_CHANNELS
             );
         }
-        println!(
+        drop_println!(
+            config,
             "\nSee https://doc.rust-lang.org/nightly/cargo/reference/unstable.html \
              for more information about these flags."
         );
@@ -58,7 +61,7 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
     let is_verbose = args.occurrences_of("verbose") > 0;
     if args.is_present("version") {
         let version = get_version_string(is_verbose);
-        print!("{}", version);
+        drop_print!(config, "{}", version);
         return Ok(());
     }
 
@@ -69,19 +72,19 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
     }
 
     if args.is_present("list") {
-        println!("Installed Commands:");
+        drop_println!(config, "Installed Commands:");
         for command in list_commands(config) {
             match command {
                 CommandInfo::BuiltIn { name, about } => {
                     let summary = about.unwrap_or_default();
                     let summary = summary.lines().next().unwrap_or(&summary); // display only the first line
-                    println!("    {:<20} {}", name, summary)
+                    drop_println!(config, "    {:<20} {}", name, summary);
                 }
                 CommandInfo::External { name, path } => {
                     if is_verbose {
-                        println!("    {:<20} {}", name, path.display())
+                        drop_println!(config, "    {:<20} {}", name, path.display());
                     } else {
-                        println!("    {}", name)
+                        drop_println!(config, "    {}", name);
                     }
                 }
             }

src/bin/cargo/commands/locate_project.rs

@@ -1,6 +1,4 @@
 use crate::command_prelude::*;
-
-use cargo::print_json;
 use serde::Serialize;
 
 pub fn cli() -> App {
@@ -30,6 +28,6 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
 
     let location = ProjectLocation { root };
 
-    print_json(&location);
+    config.shell().print_json(&location);
     Ok(())
 }

src/bin/cargo/commands/metadata.rs

@@ -1,7 +1,5 @@
 use crate::command_prelude::*;
-
 use cargo::ops::{self, OutputMetadataOptions};
-use cargo::print_json;
 
 pub fn cli() -> App {
     subcommand("metadata")
@@ -54,6 +52,6 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     };
 
     let result = ops::output_metadata(&ws, &options)?;
-    print_json(&result);
+    config.shell().print_json(&result);
     Ok(())
 }

src/bin/cargo/commands/pkgid.rs

@@ -37,6 +37,6 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let ws = args.workspace(config)?;
     let spec = args.value_of("spec").or_else(|| args.value_of("package"));
     let spec = ops::pkgid(&ws, spec)?;
-    println!("{}", spec);
+    cargo::drop_println!(config, "{}", spec);
     Ok(())
 }

src/bin/cargo/commands/read_manifest.rs

@@ -1,7 +1,5 @@
 use crate::command_prelude::*;
 
-use cargo::print_json;
-
 pub fn cli() -> App {
     subcommand("read-manifest")
         .about(
@@ -17,6 +15,6 @@ Deprecated, use `cargo metadata --no-deps` instead.\
 
 pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let ws = args.workspace(config)?;
-    print_json(&ws.current()?);
+    config.shell().print_json(&ws.current()?);
     Ok(())
 }

src/bin/cargo/commands/tree.rs

@@ -102,7 +102,7 @@ pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     if args.is_present("version") {
         let verbose = args.occurrences_of("verbose") > 0;
         let version = cli::get_version_string(verbose);
-        print!("{}", version);
+        cargo::drop_print!(config, "{}", version);
         return Ok(());
     }
     let prefix = if args.is_present("no-indent") {

src/bin/cargo/commands/verify_project.rs

@@ -3,8 +3,6 @@ use crate::command_prelude::*;
 use std::collections::HashMap;
 use std::process;
 
-use cargo::print_json;
-
 pub fn cli() -> App {
     subcommand("verify-project")
         .about("Check correctness of crate manifest")
@@ -13,19 +11,15 @@ pub fn cli() -> App {
 }
 
 pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
-    fn fail(reason: &str, value: &str) -> ! {
+    if let Err(e) = args.workspace(config) {
         let mut h = HashMap::new();
-        h.insert(reason.to_string(), value.to_string());
-        print_json(&h);
+        h.insert("invalid".to_string(), e.to_string());
+        config.shell().print_json(&h);
         process::exit(1)
     }
 
-    if let Err(e) = args.workspace(config) {
-        fail("invalid", &e.to_string())
-    }
-
     let mut h = HashMap::new();
     h.insert("success".to_string(), "true".to_string());
-    print_json(&h);
+    config.shell().print_json(&h);
     Ok(())
 }

src/bin/cargo/commands/version.rs

@@ -1,16 +1,15 @@
-use crate::command_prelude::*;
-
 use crate::cli;
+use crate::command_prelude::*;
 
 pub fn cli() -> App {
     subcommand("version")
         .about("Show version information")
         .arg(opt("quiet", "No output printed to stdout").short("q"))
 }
 
-pub fn exec(_config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
+pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let verbose = args.occurrences_of("verbose") > 0;
     let version = cli::get_version_string(verbose);
-    print!("{}", version);
+    cargo::drop_print!(config, "{}", version);
     Ok(())
 }

src/cargo/core/compiler/build_plan.rs

@@ -14,7 +14,7 @@ use serde::Serialize;
 use super::context::OutputFile;
 use super::{CompileKind, CompileMode, Context, Unit};
 use crate::core::TargetKind;
-use crate::util::{internal, CargoResult, ProcessBuilder};
+use crate::util::{internal, CargoResult, Config, ProcessBuilder};
 
 #[derive(Debug, Serialize)]
 struct Invocation {
@@ -146,9 +146,9 @@ impl BuildPlan {
         self.plan.inputs = inputs;
     }
 
-    pub fn output_plan(self) {
+    pub fn output_plan(self, config: &Config) {
         let encoded = serde_json::to_string(&self.plan).unwrap();
-        println!("{}", encoded);
+        crate::drop_println!(config, "{}", encoded);
     }
 }
 

src/cargo/core/compiler/context/mod.rs

@@ -157,7 +157,7 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
 
         if build_plan {
             plan.set_inputs(self.build_plan_inputs()?);
-            plan.output_plan();
+            plan.output_plan(self.bcx.config);
         }
 
         // Collect the result of the build into `self.compilation`.

src/cargo/core/compiler/job_queue.rs

@@ -500,7 +500,7 @@ impl<'cfg> DrainState<'cfg> {
                 plan.update(&module_name, &cmd, &filenames)?;
             }
             Message::Stdout(out) => {
-                cx.bcx.config.shell().stdout_println(out);
+                writeln!(cx.bcx.config.shell().out(), "{}", out)?;
             }
             Message::Stderr(err) => {
                 let mut shell = cx.bcx.config.shell();
@@ -700,7 +700,7 @@ impl<'cfg> DrainState<'cfg> {
                 success: error.is_none(),
             }
             .to_json_string();
-            cx.bcx.config.shell().stdout_println(msg);
+            writeln!(cx.bcx.config.shell().out(), "{}", msg)?;
         }
 
         if let Some(e) = error {

src/cargo/core/compiler/mod.rs

@@ -146,7 +146,7 @@ fn compile<'cfg>(
                     &unit.target,
                     cx.files().message_cache_path(unit),
                     cx.bcx.build_config.message_format,
-                    cx.bcx.config.shell().supports_color(),
+                    cx.bcx.config.shell().err_supports_color(),
                 )
             } else {
                 Work::noop()
@@ -1109,7 +1109,7 @@ struct OutputOptions {
 impl OutputOptions {
     fn new(cx: &Context<'_, '_>, unit: &Unit) -> OutputOptions {
         let look_for_metadata_directive = cx.rmeta_required(unit);
-        let color = cx.bcx.config.shell().supports_color();
+        let color = cx.bcx.config.shell().err_supports_color();
         let path = cx.files().message_cache_path(unit);
         // Remove old cache, ignore ENOENT, which is the common case.
         drop(fs::remove_file(&path));

src/cargo/core/compiler/timings.rs

@@ -245,7 +245,7 @@ impl<'cfg> Timings<'cfg> {
                 rmeta_time: unit_time.rmeta_time,
             }
             .to_json_string();
-            self.config.shell().stdout_println(msg);
+            crate::drop_println!(self.config, "{}", msg);
         }
         self.unit_times.push(unit_time);
     }

src/cargo/core/compiler/unit_graph.rs

@@ -113,6 +113,6 @@ pub fn emit_serialized_unit_graph(root_units: &[Unit], unit_graph: &UnitGraph) -
     let stdout = std::io::stdout();
     let mut lock = stdout.lock();
     serde_json::to_writer(&mut lock, &s)?;
-    writeln!(lock)?;
+    drop(writeln!(lock));
     Ok(())
 }

src/cargo/core/manifest.rs

@@ -500,7 +500,7 @@ impl Manifest {
     pub fn print_teapot(&self, config: &Config) {
         if let Some(teapot) = self.im_a_teapot {
             if config.cli_unstable().print_im_a_teapot {
-                println!("im-a-teapot = {}", teapot);
+                crate::drop_println!(config, "im-a-teapot = {}", teapot);
             }
         }
     }

src/cargo/core/resolver/features.rs

@@ -573,9 +573,13 @@ impl<'a, 'cfg> FeatureResolver<'a, 'cfg> {
         for ((pkg_id, dep_kind), features) in &self.activated_features {
             let r_features = self.resolve.features(*pkg_id);
             if !r_features.iter().eq(features.iter()) {
-                eprintln!(
+                crate::drop_eprintln!(
+                    self.ws.config(),
                     "{}/{:?} features mismatch\nresolve: {:?}\nnew: {:?}\n",
-                    pkg_id, dep_kind, r_features, features
+                    pkg_id,
+                    dep_kind,
+                    r_features,
+                    features
                 );
                 found = true;
             }