From 3f413d2abb5cf5f72002bc7da5709bf6c4dab444 Mon Sep 17 00:00:00 2001
From: David Wood <david.wood@huawei.com>
Date: Fri, 6 May 2022 03:44:41 +0100
Subject: [PATCH] sess: add `create_{err,warning}`

Currently, the only API for creating errors from a diagnostic derive
will emit it immediately. This makes it difficult to add subdiagnostics
to diagnostics from the derive, so add `create_{err,warning}` functions
that return the diagnostic without emitting it.

Signed-off-by: David Wood <david.wood@huawei.com>
---
 compiler/rustc_session/src/parse.rs   | 18 ++++++++++++++++--
 compiler/rustc_session/src/session.rs | 12 ++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index e933fe1cb241..6fb87e15a330 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -289,12 +289,26 @@ impl ParseSess {
         self.proc_macro_quoted_spans.lock().clone()
     }
 
+    pub fn create_err<'a>(
+        &'a self,
+        err: impl SessionDiagnostic<'a>,
+    ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
+        err.into_diagnostic(self)
+    }
+
     pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
-        err.into_diagnostic(self).emit()
+        self.create_err(err).emit()
+    }
+
+    pub fn create_warning<'a>(
+        &'a self,
+        warning: impl SessionDiagnostic<'a, ()>,
+    ) -> DiagnosticBuilder<'a, ()> {
+        warning.into_diagnostic(self)
     }
 
     pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
-        warning.into_diagnostic(self).emit()
+        self.create_warning(warning).emit()
     }
 
     pub fn struct_err(
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index e8279f6fed24..b2c23cda6aae 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -413,9 +413,21 @@ impl Session {
     pub fn err(&self, msg: impl Into<DiagnosticMessage>) -> ErrorGuaranteed {
         self.diagnostic().err(msg)
     }
+    pub fn create_err<'a>(
+        &'a self,
+        err: impl SessionDiagnostic<'a>,
+    ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
+        self.parse_sess.create_err(err)
+    }
     pub fn emit_err<'a>(&'a self, err: impl SessionDiagnostic<'a>) -> ErrorGuaranteed {
         self.parse_sess.emit_err(err)
     }
+    pub fn create_warning<'a>(
+        &'a self,
+        err: impl SessionDiagnostic<'a, ()>,
+    ) -> DiagnosticBuilder<'a, ()> {
+        self.parse_sess.create_warning(err)
+    }
     pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
         self.parse_sess.emit_warning(warning)
     }