Auto merge of rust-lang#119286 - jyn514:linker-output, r=bjorn3

show linker output even if the linker succeeds

- show stderr by default
- show stdout if `--verbose` is passed
- remove both from RUSTC_LOG
- hide the linker cli args unless `--verbose` is passed

fixes rust-lang#83436. fixes rust-lang#38206. fixes rust-lang#109979. helps with rust-lang#46998. cc https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/uplift.20some.20-Zverbose.20calls.20and.20rename.20to.E2.80.A6.20compiler-team.23706/near/408986134

this is based on rust-lang#119129 for convenience so i didn't have to duplicate the changes around saving `--verbose` in rust-lang@cb6d033#diff-7a49efa20548d6806dbe1c66dd4dc445fda18fcbbf1709520cadecc4841aae12

r? `@bjorn3`

compiler/rustc_codegen_ssa/messages.ftl

@@ -172,6 +172,8 @@ codegen_ssa_linker_file_stem = couldn't extract file stem from specified linker
 codegen_ssa_linker_not_found = linker `{$linker_path}` not found
     .note = {$error}
 
+codegen_ssa_linker_output = {$inner}
+
 codegen_ssa_linker_unsupported_modifier = `as-needed` modifier not supported for current linker
 
 codegen_ssa_linking_failed = linking with `{$linker_path}` failed: {$exit_status}

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -18,6 +18,7 @@ use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_errors::{DiagCtxtHandle, ErrorGuaranteed, FatalError};
 use rustc_fs_util::{fix_windows_verbatim_for_gcc, try_canonicalize};
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
+use rustc_macros::Diagnostic;
 use rustc_metadata::fs::{copy_to_stdout, emit_wrapper_file, METADATA_FILENAME};
 use rustc_metadata::{find_native_static_library, walk_native_lib_search_dirs};
 use rustc_middle::bug;
@@ -750,6 +751,14 @@ fn link_dwarf_object(sess: &Session, cg_results: &CodegenResults, executable_out
     }
 }
 
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_linker_output)]
+/// Translating this is kind of useless. We don't pass translation flags to the linker, so we'd just
+/// end up with inconsistent languages within the same diagnostic.
+struct LinkerOutput {
+    inner: String,
+}
+
 /// Create a dynamic library or executable.
 ///
 /// This will invoke the system linker/cc to create the resulting file. This links to all upstream
@@ -976,12 +985,12 @@ fn link_natively(
                 let mut output = prog.stderr.clone();
                 output.extend_from_slice(&prog.stdout);
                 let escaped_output = escape_linker_output(&output, flavor);
-                // FIXME: Add UI tests for this error.
                 let err = errors::LinkingFailed {
                     linker_path: &linker_path,
                     exit_status: prog.status,
                     command: &cmd,
                     escaped_output,
+                    verbose: sess.opts.verbose,
                 };
                 sess.dcx().emit_err(err);
                 // If MSVC's `link.exe` was expected but the return code
@@ -1022,8 +1031,22 @@ fn link_natively(
 
                 sess.dcx().abort_if_errors();
             }
-            info!("linker stderr:\n{}", escape_string(&prog.stderr));
-            info!("linker stdout:\n{}", escape_string(&prog.stdout));
+
+            if !prog.stderr.is_empty() {
+                // We already print `warning:` at the start of the diagnostic. Remove it from the linker output if present.
+                let stderr = escape_string(&prog.stderr);
+                debug!("original stderr: {stderr}");
+                let stderr = stderr
+                    .strip_prefix("warning: ")
+                    .unwrap_or(&stderr)
+                    .replace(": warning: ", ": ");
+                sess.dcx().emit_warn(LinkerOutput { inner: format!("linker stderr: {stderr}") });
+            }
+            if !prog.stdout.is_empty() && sess.opts.verbose {
+                sess.dcx().emit_warn(LinkerOutput {
+                    inner: format!("linker stdout: {}", escape_string(&prog.stdout)),
+                });
+            }
         }
         Err(e) => {
             let linker_not_found = e.kind() == io::ErrorKind::NotFound;

compiler/rustc_codegen_ssa/src/errors.rs

@@ -348,6 +348,7 @@ pub struct LinkingFailed<'a> {
     pub exit_status: ExitStatus,
     pub command: &'a Command,
     pub escaped_output: String,
+    pub verbose: bool,
 }
 
 impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
@@ -358,7 +359,13 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
 
         let contains_undefined_ref = self.escaped_output.contains("undefined reference to");
 
-        diag.note(format!("{:?}", self.command)).note(self.escaped_output);
+        if self.verbose {
+            diag.note(format!("{:?}", self.command));
+        } else {
+            diag.note("use `--verbose` to show all linker arguments");
+        }
+
+        diag.note(self.escaped_output);
 
         // Trying to match an error from OS linkers
         // which by now we have no way to translate.

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -253,7 +253,10 @@ impl DiagnosticDeriveVariantBuilder {
         let mut field_binding = binding_info.binding.clone();
         field_binding.set_span(field.ty.span());
 
-        let ident = field.ident.as_ref().unwrap();
+        let Some(ident) = field.ident.as_ref() else {
+            span_err(field.span().unwrap(), "tuple structs are not supported").emit();
+            return TokenStream::new();
+        };
         let ident = format_ident!("{}", ident); // strip `r#` prefix, if present
 
         quote! {

compiler/rustc_macros/src/diagnostics/error.rs

@@ -56,7 +56,7 @@ fn path_to_string(path: &syn::Path) -> String {
 /// Returns an error diagnostic on span `span` with msg `msg`.
 #[must_use]
 pub(crate) fn span_err<T: Into<String>>(span: impl MultiSpan, msg: T) -> Diagnostic {
-    Diagnostic::spanned(span, Level::Error, msg)
+    Diagnostic::spanned(span, Level::Error, format!("derive(Diagnostic): {}", msg.into()))
 }
 
 /// Emit a diagnostic on span `$span` with msg `$msg` (optionally performing additional decoration

compiler/rustc_macros/src/diagnostics/utils.rs

@@ -243,7 +243,7 @@ impl<T> SetOnce<T> for SpannedOption<T> {
                 *self = Some((value, span));
             }
             Some((_, prev_span)) => {
-                span_err(span, "specified multiple times")
+                span_err(span, "attribute specified multiple times")
                     .span_note(*prev_span, "previously specified here")
                     .emit();
             }

src/etc/cat-and-grep.sh

@@ -33,7 +33,6 @@ while getopts ':vieh' OPTION; do
     case "$OPTION" in
         v)
             INVERT=1
-            ERROR_MSG='should not be found'
             ;;
         i)
             GREPFLAGS="i$GREPFLAGS"

src/tools/compiletest/src/runtest.rs

@@ -1778,6 +1778,10 @@ impl<'test> TestCx<'test> {
         self.config.target.contains("vxworks") && !self.is_vxworks_pure_static()
     }
 
+    fn has_aux_dir(&self) -> bool {
+        !self.props.aux_builds.is_empty() || !self.props.aux_crates.is_empty()
+    }
+
     fn aux_output_dir(&self) -> PathBuf {
         let aux_dir = self.aux_output_dir_name();
 
@@ -2324,7 +2328,11 @@ impl<'test> TestCx<'test> {
         }
 
         if let LinkToAux::Yes = link_to_aux {
-            rustc.arg("-L").arg(self.aux_output_dir_name());
+            // if we pass an `-L` argument to a directory that doesn't exist,
+            // macOS ld emits warnings which disrupt the .stderr files
+            if self.has_aux_dir() {
+                rustc.arg("-L").arg(self.aux_output_dir_name());
+            }
         }
 
         rustc.args(&self.props.compile_flags);

src/tools/run-make-support/src/external_deps/rustc.rs

@@ -319,6 +319,12 @@ impl Rustc {
         self
     }
 
+    /// Pass the `--verbose` flag.
+    pub fn verbose(&mut self) -> &mut Self {
+        self.cmd.arg("--verbose");
+        self
+    }
+
     /// `EXTRARSCXXFLAGS`
     pub fn extra_rs_cxx_flags(&mut self) -> &mut Self {
         // Adapted from tools.mk (trimmed):

tests/run-make/link-args-order/rmake.rs

@@ -15,15 +15,17 @@ fn main() {
         .link_args("b c")
         .link_args("d e")
         .link_arg("f")
+        .arg("--print=link-args")
         .run_fail()
-        .assert_stderr_contains(r#""a" "b" "c" "d" "e" "f""#);
+        .assert_stdout_contains(r#""a" "b" "c" "d" "e" "f""#);
     rustc()
         .input("empty.rs")
         .linker_flavor(linker)
         .arg("-Zpre-link-arg=a")
         .arg("-Zpre-link-args=b c")
         .arg("-Zpre-link-args=d e")
         .arg("-Zpre-link-arg=f")
+        .arg("--print=link-args")
         .run_fail()
-        .assert_stderr_contains(r#""a" "b" "c" "d" "e" "f""#);
+        .assert_stdout_contains(r#""a" "b" "c" "d" "e" "f""#);
 }

tests/run-make/link-dedup/rmake.rs

@@ -14,13 +14,13 @@ fn main() {
     rustc().input("depb.rs").run();
     rustc().input("depc.rs").run();
 
-    let output = rustc().input("empty.rs").cfg("bar").run_fail();
-    output.assert_stderr_contains(needle_from_libs(&["testa", "testb", "testa"]));
+    let output = rustc().input("empty.rs").cfg("bar").arg("--print=link-args").run_fail();
+    output.assert_stdout_contains(needle_from_libs(&["testa", "testb", "testa"]));
 
-    let output = rustc().input("empty.rs").run_fail();
-    output.assert_stderr_contains(needle_from_libs(&["testa"]));
-    output.assert_stderr_not_contains(needle_from_libs(&["testb"]));
-    output.assert_stderr_not_contains(needle_from_libs(&["testa", "testa", "testa"]));
+    let output = rustc().input("empty.rs").arg("--print=link-args").run_fail();
+    output.assert_stdout_contains(needle_from_libs(&["testa"]));
+    output.assert_stdout_not_contains(needle_from_libs(&["testb"]));
+    output.assert_stdout_not_contains(needle_from_libs(&["testa", "testa", "testa"]));
     // Adjacent identical native libraries are no longer deduplicated if
     // they come from different crates (https://github.com/rust-lang/rust/pull/103311)
     // so the following will fail:

tests/run-make/linker-warning/fake-linker.rs

@@ -0,0 +1,13 @@
+fn main() {
+    for arg in std::env::args() {
+        match &*arg {
+            "run_make_info" => println!("foo"),
+            "run_make_warn" => eprintln!("warning: bar"),
+            "run_make_error" => {
+                eprintln!("error: baz");
+                std::process::exit(1);
+            }
+            _ => (),
+        }
+    }
+}

tests/run-make/linker-warning/fake-linker.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+code=0
+while ! [ $# = 0 ]; do
+    case "$1" in
+        run_make_info) echo "foo"
+            ;;
+        run_make_warn) echo "warning: bar" >&2
+            ;;
+        run_make_error) echo "error: baz" >&2; code=1
+            ;;
+        *) ;;   # rustc passes lots of args we don't care about
+    esac
+    shift
+done
+
+exit $code

tests/run-make/linker-warning/main.rs

@@ -0,0 +1 @@
+fn main() {}

tests/run-make/linker-warning/rmake.rs

@@ -0,0 +1,45 @@
+use std::path::Path;
+
+use run_make_support::rfs::remove_file;
+use run_make_support::{rustc, Rustc};
+
+fn run_rustc() -> Rustc {
+    let mut rustc = rustc();
+    rustc.arg("main.rs").output("main").linker("./fake-linker");
+    rustc
+}
+
+fn main() {
+    // first, compile our linker
+    rustc().arg("fake-linker.rs").output("fake-linker").run();
+
+    // Run rustc with our fake linker, and make sure it shows warnings
+    let warnings = run_rustc().link_arg("run_make_warn").run();
+    warnings.assert_stderr_contains("warning: linker stderr: bar");
+
+    // Make sure it shows stdout, but only when --verbose is passed
+    run_rustc()
+        .link_arg("run_make_info")
+        .verbose()
+        .run()
+        .assert_stderr_contains("warning: linker stdout: foo");
+    run_rustc()
+        .link_arg("run_make_info")
+        .run()
+        .assert_stderr_not_contains("warning: linker stdout: foo");
+
+    // Make sure we short-circuit this new path if the linker exits with an error
+    // (so the diagnostic is less verbose)
+    run_rustc().link_arg("run_make_error").run_fail().assert_stderr_contains("note: error: baz");
+
+    // Make sure we don't show the linker args unless `--verbose` is passed
+    run_rustc()
+        .link_arg("run_make_error")
+        .verbose()
+        .run_fail()
+        .assert_stderr_contains_regex("fake-linker.*run_make_error");
+    run_rustc()
+        .link_arg("run_make_error")
+        .run_fail()
+        .assert_stderr_not_contains_regex("fake-linker.*run_make_error");
+}

tests/run-make/rust-lld/rmake.rs

@@ -14,10 +14,10 @@ fn main() {
     // Opt-in to lld and the self-contained linker, to link with rust-lld. We'll check that by
     // asking the linker to display its version number with a link-arg.
     let output = rustc()
-        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
         .arg("-Zlinker-features=+lld")
         .arg("-Clink-self-contained=+linker")
         .arg("-Zunstable-options")
+        .arg("--verbose")
         .link_arg(linker_version_flag)
         .input("main.rs")
         .run();
@@ -29,8 +29,8 @@ fn main() {
 
     // It should not be used when we explicitly opt-out of lld.
     let output = rustc()
-        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
         .link_arg(linker_version_flag)
+        .arg("--verbose")
         .arg("-Zlinker-features=-lld")
         .input("main.rs")
         .run();
@@ -43,8 +43,8 @@ fn main() {
     // While we're here, also check that the last linker feature flag "wins" when passed multiple
     // times to rustc.
     let output = rustc()
-        .env("RUSTC_LOG", "rustc_codegen_ssa::back::link=info")
         .link_arg(linker_version_flag)
+        .arg("--verbose")
         .arg("-Clink-self-contained=+linker")
         .arg("-Zunstable-options")
         .arg("-Zlinker-features=-lld")
@@ -60,6 +60,7 @@ fn main() {
 }
 
 fn find_lld_version_in_logs(stderr: String) -> bool {
-    let lld_version_re = Regex::new(r"^LLD [0-9]+\.[0-9]+\.[0-9]+").unwrap();
+    let lld_version_re =
+        Regex::new(r"^warning: linker stdout: LLD [0-9]+\.[0-9]+\.[0-9]+").unwrap();
     stderr.lines().any(|line| lld_version_re.is_match(line.trim()))
 }