From d49d136b3a0e9749e4aa517b7aa6490752444cf7 Mon Sep 17 00:00:00 2001
From: Yacin Tmimi <yacintmimi@gmail.com>
Date: Tue, 19 Mar 2024 12:58:23 -0400
Subject: [PATCH] conditionally ignore fatal diagnostic in the SilentEmitter

This change is primarily meant to allow rustfmt to ignore all
diagnostics when using the `SilentEmitter`. Back in PR 121301 the
`SilentEmitter` was shared between rustc and rustfmt. This changed
rustfmt's behavior from ignoring all diagnostic to emitting fatal
diagnostics.

These changes allow rustfmt to maintain it's previous behaviour when
using the SilentEmitter, while allowing rustc code to still emit fatal
diagnostics.
---
 compiler/rustc_errors/src/emitter.rs      | 3 ++-
 compiler/rustc_errors/src/lib.rs          | 8 +++++++-
 compiler/rustc_interface/src/interface.rs | 2 ++
 compiler/rustc_session/src/parse.rs       | 7 ++++++-
 src/tools/rustfmt/src/parse/session.rs    | 3 ++-
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 4f033e3fefa0f..f5d275fc45227 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -541,6 +541,7 @@ pub struct SilentEmitter {
     pub fallback_bundle: LazyFallbackBundle,
     pub fatal_dcx: DiagCtxt,
     pub fatal_note: Option<String>,
+    pub emit_fatal_diagnostic: bool,
 }
 
 impl Translate for SilentEmitter {
@@ -561,7 +562,7 @@ impl Emitter for SilentEmitter {
     }
 
     fn emit_diagnostic(&mut self, mut diag: DiagInner) {
-        if diag.level == Level::Fatal {
+        if self.emit_fatal_diagnostic && diag.level == Level::Fatal {
             if let Some(fatal_note) = &self.fatal_note {
                 diag.sub(Level::Note, fatal_note.clone(), MultiSpan::new());
             }
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 723f13dbe8d31..ff5e1948db880 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -613,12 +613,18 @@ impl DiagCtxt {
         Self { inner: Lock::new(DiagCtxtInner::new(emitter)) }
     }
 
-    pub fn make_silent(&mut self, fallback_bundle: LazyFallbackBundle, fatal_note: Option<String>) {
+    pub fn make_silent(
+        &mut self,
+        fallback_bundle: LazyFallbackBundle,
+        fatal_note: Option<String>,
+        emit_fatal_diagnostic: bool,
+    ) {
         self.wrap_emitter(|old_dcx| {
             Box::new(emitter::SilentEmitter {
                 fallback_bundle,
                 fatal_dcx: DiagCtxt { inner: Lock::new(old_dcx) },
                 fatal_note,
+                emit_fatal_diagnostic,
             })
         });
     }
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 1a82e6c6910ae..edf52fe8c347d 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -48,6 +48,7 @@ pub(crate) fn parse_cfg(dcx: &DiagCtxt, cfgs: Vec<String>) -> Cfg {
             let psess = ParseSess::with_silent_emitter(
                 vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
                 format!("this error occurred on the command line: `--cfg={s}`"),
+                true,
             );
             let filename = FileName::cfg_spec_source_code(&s);
 
@@ -111,6 +112,7 @@ pub(crate) fn parse_check_cfg(dcx: &DiagCtxt, specs: Vec<String>) -> CheckCfg {
         let psess = ParseSess::with_silent_emitter(
             vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
             format!("this error occurred on the command line: `--check-cfg={s}`"),
+            true,
         );
         let filename = FileName::cfg_spec_source_code(&s);
 
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 5434bbe0b98a2..f6053f43fbd19 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -269,7 +269,11 @@ impl ParseSess {
         }
     }
 
-    pub fn with_silent_emitter(locale_resources: Vec<&'static str>, fatal_note: String) -> Self {
+    pub fn with_silent_emitter(
+        locale_resources: Vec<&'static str>,
+        fatal_note: String,
+        emit_fatal_diagnostic: bool,
+    ) -> Self {
         let fallback_bundle = fallback_fluent_bundle(locale_resources, false);
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let emitter = Box::new(HumanEmitter::new(
@@ -281,6 +285,7 @@ impl ParseSess {
             fallback_bundle,
             fatal_dcx,
             fatal_note: Some(fatal_note),
+            emit_fatal_diagnostic,
         }))
         .disable_warnings();
         ParseSess::with_dcx(dcx, sm)
diff --git a/src/tools/rustfmt/src/parse/session.rs b/src/tools/rustfmt/src/parse/session.rs
index cb46e65999df6..1a39d212386bd 100644
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@@ -121,6 +121,7 @@ fn default_dcx(
             fallback_bundle,
             fatal_dcx: DiagCtxt::new(emitter),
             fatal_note: None,
+            emit_fatal_diagnostic: false,
         })
     } else {
         emitter
@@ -209,7 +210,7 @@ impl ParseSess {
             rustc_driver::DEFAULT_LOCALE_RESOURCES.to_vec(),
             false,
         );
-        self.raw_psess.dcx.make_silent(fallback_bundle, None);
+        self.raw_psess.dcx.make_silent(fallback_bundle, None, false);
     }
 
     pub(crate) fn span_to_filename(&self, span: Span) -> FileName {