From b78b15665b622cc37b25e9bd971537296403b83d Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Tue, 26 May 2020 20:07:59 +0100
Subject: Improve inline asm error diagnostics

---
 src/librustc_codegen_ssa/back/write.rs | 39 ++++++++++++++++++++++++++++------
 src/librustc_codegen_ssa/mir/block.rs  | 12 +++++++++--
 src/librustc_codegen_ssa/traits/asm.rs |  2 +-
 3 files changed, 44 insertions(+), 9 deletions(-)

(limited to 'src/librustc_codegen_ssa')

diff --git a/src/librustc_codegen_ssa/back/write.rs b/src/librustc_codegen_ssa/back/write.rs
index 9e03c283cfb..cb5c95c11fa 100644
--- a/src/librustc_codegen_ssa/back/write.rs
+++ b/src/librustc_codegen_ssa/back/write.rs
@@ -31,9 +31,9 @@ use rustc_session::cgu_reuse_tracker::CguReuseTracker;
 use rustc_session::config::{self, CrateType, Lto, OutputFilenames, OutputType};
 use rustc_session::config::{Passes, Sanitizer, SwitchWithOptPath};
 use rustc_session::Session;
-use rustc_span::hygiene::ExpnId;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{sym, Symbol};
+use rustc_span::{BytePos, FileName, InnerSpan, Pos, Span};
 use rustc_target::spec::{MergeFunctions, PanicStrategy};
 
 use std::any::Any;
@@ -1551,7 +1551,7 @@ fn spawn_work<B: ExtraBackendMethods>(cgcx: CodegenContext<B>, work: WorkItem<B>
 
 enum SharedEmitterMessage {
     Diagnostic(Diagnostic),
-    InlineAsmError(u32, String),
+    InlineAsmError(u32, String, Option<(String, Vec<InnerSpan>)>),
     AbortIfErrors,
     Fatal(String),
 }
@@ -1572,8 +1572,13 @@ impl SharedEmitter {
         (SharedEmitter { sender }, SharedEmitterMain { receiver })
     }
 
-    pub fn inline_asm_error(&self, cookie: u32, msg: String) {
-        drop(self.sender.send(SharedEmitterMessage::InlineAsmError(cookie, msg)));
+    pub fn inline_asm_error(
+        &self,
+        cookie: u32,
+        msg: String,
+        source: Option<(String, Vec<InnerSpan>)>,
+    ) {
+        drop(self.sender.send(SharedEmitterMessage::InlineAsmError(cookie, msg, source)));
     }
 
     pub fn fatal(&self, msg: &str) {
@@ -1626,8 +1631,30 @@ impl SharedEmitterMain {
                     }
                     handler.emit_diagnostic(&d);
                 }
-                Ok(SharedEmitterMessage::InlineAsmError(cookie, msg)) => {
-                    sess.span_err(ExpnId::from_u32(cookie).expn_data().call_site, &msg)
+                Ok(SharedEmitterMessage::InlineAsmError(cookie, msg, source)) => {
+                    let msg = msg.strip_prefix("error: ").unwrap_or(&msg);
+
+                    // If the cookie is 0 then we don't have span information.
+                    let mut err = if cookie == 0 {
+                        sess.struct_err(&msg)
+                    } else {
+                        let pos = BytePos::from_u32(cookie);
+                        let span = Span::with_root_ctxt(pos, pos);
+                        sess.struct_span_err(span, &msg)
+                    };
+
+                    // Point to the generated assembly if it is available.
+                    if let Some((buffer, spans)) = source {
+                        let source = sess
+                            .source_map()
+                            .new_source_file(FileName::inline_asm_source_code(&buffer), buffer);
+                        let source_span = Span::with_root_ctxt(source.start_pos, source.end_pos);
+                        let spans: Vec<_> =
+                            spans.iter().map(|sp| source_span.from_inner(*sp)).collect();
+                        err.span_note(spans, "instantiated into assembly here");
+                    }
+
+                    err.emit();
                 }
                 Ok(SharedEmitterMessage::AbortIfErrors) => {
                     sess.abort_if_errors();
diff --git a/src/librustc_codegen_ssa/mir/block.rs b/src/librustc_codegen_ssa/mir/block.rs
index b487ed8dea8..e0c6fb451fc 100644
--- a/src/librustc_codegen_ssa/mir/block.rs
+++ b/src/librustc_codegen_ssa/mir/block.rs
@@ -831,6 +831,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         template: &[ast::InlineAsmTemplatePiece],
         operands: &[mir::InlineAsmOperand<'tcx>],
         options: ast::InlineAsmOptions,
+        line_spans: &[Span],
         destination: Option<mir::BasicBlock>,
     ) {
         let span = terminator.source_info.span;
@@ -931,7 +932,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             })
             .collect();
 
-        bx.codegen_inline_asm(template, &operands, options, span);
+        bx.codegen_inline_asm(template, &operands, options, line_spans);
 
         if let Some(target) = destination {
             helper.funclet_br(self, &mut bx, target);
@@ -1034,7 +1035,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 bug!("borrowck false edges in codegen")
             }
 
-            mir::TerminatorKind::InlineAsm { template, ref operands, options, destination } => {
+            mir::TerminatorKind::InlineAsm {
+                template,
+                ref operands,
+                options,
+                line_spans,
+                destination,
+            } => {
                 self.codegen_asm_terminator(
                     helper,
                     bx,
@@ -1042,6 +1049,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     template,
                     operands,
                     options,
+                    line_spans,
                     destination,
                 );
             }
diff --git a/src/librustc_codegen_ssa/traits/asm.rs b/src/librustc_codegen_ssa/traits/asm.rs
index 0abfdfde780..b6b57744f95 100644
--- a/src/librustc_codegen_ssa/traits/asm.rs
+++ b/src/librustc_codegen_ssa/traits/asm.rs
@@ -52,7 +52,7 @@ pub trait AsmBuilderMethods<'tcx>: BackendTypes {
         template: &[InlineAsmTemplatePiece],
         operands: &[InlineAsmOperandRef<'tcx, Self>],
         options: InlineAsmOptions,
-        span: Span,
+        line_spans: &[Span],
     );
 }
 
-- 
cgit 1.4.1-3-g733a5