rustc: improve E0669 span

E0669 refers to a constraint that cannot be coerced into a single LLVM
value, unfortunately right now this uses the Span for the entire inline
assembly statement, which is less than ideal.

This commit preserves the Span from HIR, which lets us emit the error
using the Span for the operand itself in MIR.

Signed-off-by: Levente Kurusa <lkurusa@acm.org>

src/librustc/mir/mod.rs

@@ -1713,7 +1713,7 @@ pub enum StatementKind<'tcx> {
     InlineAsm {
         asm: Box<InlineAsm>,
         outputs: Box<[Place<'tcx>]>,
-        inputs: Box<[Operand<'tcx>]>,
+        inputs: Box<[(Span, Operand<'tcx>)]>,
     },
 
     /// Assert the given places to be valid inhabitants of their type.  These statements are

src/librustc/mir/visit.rs

@@ -383,7 +383,8 @@ fn super_statement(&mut self,
                         for output in & $($mutability)* outputs[..] {
                             self.visit_place(output, PlaceContext::AsmOutput, location);
                         }
-                        for input in & $($mutability)* inputs[..] {
+                        for (span, input) in & $($mutability)* inputs[..] {
+                            self.visit_span(span);
                             self.visit_operand(input, location);
                         }
                     }

src/librustc_codegen_llvm/mir/statement.rs

@@ -84,18 +84,18 @@ pub fn codegen_statement(&mut self,
                 }).collect();
 
                 let input_vals = inputs.iter()
-                    .try_fold(Vec::with_capacity(inputs.len()), |mut acc, input| {
+                    .try_fold(Vec::with_capacity(inputs.len()), |mut acc, (span, input)| {
                         let op = self.codegen_operand(&bx, input);
                         if let OperandValue::Immediate(_) = op.val {
                             acc.push(op.immediate());
                             Ok(acc)
                         } else {
-                            Err(op)
+                            Err(span)
                         }
                 });
 
-                if input_vals.is_err() {
-                   span_err!(bx.sess(), statement.source_info.span, E0669,
+                if let Err(span) = input_vals {
+                    span_err!(bx.sess(), span.to_owned(), E0669,
                              "invalid value for constraint in inline assembly");
                 } else {
                     let input_vals = input_vals.unwrap();

src/librustc_mir/borrow_check/mod.rs

@@ -565,7 +565,7 @@ fn visit_statement_entry(
                         );
                     }
                 }
-                for input in inputs.iter() {
+                for (_, input) in inputs.iter() {
                     self.consume_operand(context, (input, span), flow_state);
                 }
             }

src/librustc_mir/borrow_check/nll/invalidation.rs

@@ -128,7 +128,7 @@ fn visit_statement(&mut self,
                         );
                     }
                 }
-                for input in inputs.iter() {
+                for (_, input) in inputs.iter() {
                     self.consume_operand(context, input);
                 }
             }

src/librustc_mir/build/expr/stmt.rs

@@ -167,8 +167,12 @@ pub fn stmt_expr(&mut self, mut block: BasicBlock, expr: Expr<'tcx>) -> BlockAnd
                     .into_boxed_slice();
                 let inputs = inputs
                     .into_iter()
-                    .map(|input| unpack!(block = this.as_local_operand(block, input)))
-                    .collect::<Vec<_>>()
+                    .map(|input| {
+                        (
+                            input.span(),
+                            unpack!(block = this.as_local_operand(block, input)),
+                        )
+                    }).collect::<Vec<_>>()
                     .into_boxed_slice();
                 this.cfg.push(
                     block,

src/librustc_mir/dataflow/move_paths/builder.rs

@@ -290,7 +290,7 @@ fn gather_statement(&mut self, stmt: &Statement<'tcx>) {
                         self.gather_init(output, InitKind::Deep);
                     }
                 }
-                for input in inputs.iter() {
+                for (_, input) in inputs.iter() {
                     self.gather_operand(input);
                 }
             }

src/test/ui/inline-asm-bad-operand.stderr

@@ -1,32 +1,32 @@
 error[E0669]: invalid value for constraint in inline assembly
-  --> $DIR/inline-asm-bad-operand.rs:28:9
+  --> $DIR/inline-asm-bad-operand.rs:28:24
    |
 LL |         asm!("" :: "r"("")); //~ ERROR E0669
-   |         ^^^^^^^^^^^^^^^^^^^^
+   |                        ^^
 
 error[E0669]: invalid value for constraint in inline assembly
-  --> $DIR/inline-asm-bad-operand.rs:33:9
+  --> $DIR/inline-asm-bad-operand.rs:33:32
    |
 LL |         asm!("ret" : : "{rdi}"(target)); //~ ERROR E0669
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                ^^^^^^
 
 error[E0669]: invalid value for constraint in inline assembly
-  --> $DIR/inline-asm-bad-operand.rs:40:14
+  --> $DIR/inline-asm-bad-operand.rs:40:29
    |
 LL |     unsafe { asm!("" :: "i"(hello)) }; //~ ERROR E0669
-   |              ^^^^^^^^^^^^^^^^^^^^^^
+   |                             ^^^^^
 
 error[E0669]: invalid value for constraint in inline assembly
-  --> $DIR/inline-asm-bad-operand.rs:48:9
+  --> $DIR/inline-asm-bad-operand.rs:48:38
    |
 LL |         asm!("movups $1, %xmm0"::"m"(arr)); //~ ERROR E0669
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                      ^^^
 
 error[E0669]: invalid value for constraint in inline assembly
-  --> $DIR/inline-asm-bad-operand.rs:55:9
+  --> $DIR/inline-asm-bad-operand.rs:55:32
    |
 LL |         asm!("mov sp, $0"::"r"(addr)); //~ ERROR E0669
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                ^^^^
 
 error: aborting due to 5 previous errors