Auto merge of #1283 - RalfJung:backtrace, r=RalfJung

Make backtrace function names and spans match up

This is the Miri side of rust-lang/rust#70590.
Fixes #521

rust-version

@@ -1 +1 @@
-235938d1acdd93d6641a741c81f64e415b786751
+b793f403bdfbcc0ff3e15ed8177a81d79ba4a29b

src/diagnostics.rs

@@ -129,15 +129,12 @@ fn report_msg<'tcx, 'mir>(
         err.help(help);
     }
     // Add backtrace
-    let frames = ecx.generate_stacktrace(None);
-    // We iterate with indices because we need to look at the next frame (the caller).
-    for idx in 0..frames.len() {
-        let frame_info = &frames[idx];
-        let call_site_is_local = frames
-            .get(idx + 1)
-            .map_or(false, |caller_info| caller_info.instance.def_id().is_local());
-        if call_site_is_local {
-            err.span_note(frame_info.call_site, &frame_info.to_string());
+    let frames = ecx.generate_stacktrace();
+    for (idx, frame_info) in frames.iter().enumerate() {
+        let is_local = frame_info.instance.def_id().is_local();
+        // No span for non-local frames and the first frame (which is the error site).
+        if is_local && idx > 0 {
+            err.span_note(frame_info.span, &frame_info.to_string());
         } else {
             err.note(&frame_info.to_string());
         }

src/helpers.rs

@@ -10,7 +10,6 @@ use rustc_middle::ty::{
     List, TyCtxt,
 };
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
-use rustc_span::source_map::DUMMY_SP;
 
 use rand::RngCore;
 
@@ -170,13 +169,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
         // Push frame.
         let mir = &*this.load_mir(f.def, None)?;
-        let span = this
-            .stack()
-            .last()
-            .and_then(Frame::current_source_info)
-            .map(|si| si.span)
-            .unwrap_or(DUMMY_SP);
-        this.push_stack_frame(f, span, mir, dest, stack_pop)?;
+        this.push_stack_frame(f, mir, dest, stack_pop)?;
 
         // Initialize arguments.
         let mut callee_args = this.frame().body.args_iter();
@@ -331,19 +324,19 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 fields: impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Tag>>>,
             ) -> InterpResult<'tcx> {
                 match place.layout.fields {
-                    layout::FieldPlacement::Array { .. } => {
+                    layout::FieldsShape::Array { .. } => {
                         // For the array layout, we know the iterator will yield sorted elements so
                         // we can avoid the allocation.
                         self.walk_aggregate(place, fields)
                     }
-                    layout::FieldPlacement::Arbitrary { .. } => {
+                    layout::FieldsShape::Arbitrary { .. } => {
                         // Gather the subplaces and sort them before visiting.
                         let mut places =
                             fields.collect::<InterpResult<'tcx, Vec<MPlaceTy<'tcx, Tag>>>>()?;
                         places.sort_by_key(|place| place.ptr.assert_ptr().offset);
                         self.walk_aggregate(place, places.into_iter().map(Ok))
                     }
-                    layout::FieldPlacement::Union { .. } => {
+                    layout::FieldsShape::Union { .. } => {
                         // Uh, what?
                         bug!("a union is not an aggregate we should ever visit")
                     }

src/machine.rs

@@ -18,7 +18,7 @@ use rustc_middle::ty::{
     Ty,
 };
 use rustc_ast::attr;
-use rustc_span::{source_map::Span, symbol::{sym, Symbol}};
+use rustc_span::symbol::{sym, Symbol};
 
 use crate::*;
 
@@ -253,7 +253,6 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
     #[inline(always)]
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
@@ -276,13 +275,12 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
     #[inline(always)]
     fn call_intrinsic(
         ecx: &mut rustc_mir::interpret::InterpCx<'mir, 'tcx, Self>,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx> {
-        ecx.call_intrinsic(span, instance, args, ret, unwind)
+        ecx.call_intrinsic(instance, args, ret, unwind)
     }
 
     #[inline(always)]

src/shims/intrinsics.rs

@@ -5,22 +5,20 @@ use rustc_middle::mir;
 use rustc_middle::ty;
 use rustc_middle::ty::layout::{Align, LayoutOf};
 use rustc_apfloat::Float;
-use rustc_span::source_map::Span;
 
 use crate::*;
 
 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
     fn call_intrinsic(
         &mut self,
-        span: Span,
         instance: ty::Instance<'tcx>,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
-        if this.emulate_intrinsic(span, instance, args, ret)? {
+        if this.emulate_intrinsic(instance, args, ret)? {
             return Ok(());
         }
         let substs = instance.substs;

src/shims/panic.rs

@@ -51,7 +51,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
 
-        trace!("miri_start_panic: {:?}", this.frame().span);
+        trace!("miri_start_panic: {:?}", this.frame().instance);
 
         // Get the raw pointer stored in arg[0] (the panic payload).
         let payload = this.read_scalar(args[0])?.not_undef()?;
@@ -133,7 +133,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         if let (true, Some(catch_unwind)) = (unwinding, extra.catch_unwind.take()) {
             // We've just popped a frame that was pushed by `try`,
             // and we are unwinding, so we should catch that.
-            trace!("unwinding: found catch_panic frame during unwinding: {:?}", this.frame().span);
+            trace!("unwinding: found catch_panic frame during unwinding: {:?}", this.frame().instance);
 
             // We set the return value of `try` to 1, since there was a panic.
             this.write_scalar(Scalar::from_i32(1), catch_unwind.dest)?;

tests/compile-fail/never_transmute_void.rs

@@ -7,12 +7,12 @@
 enum Void {}
 
 fn f(v: Void) -> ! {
-    match v {} //~ ERROR  entering unreachable code
+    match v {} //~ ERROR entering unreachable code
 }
 
 fn main() {
     let v: Void = unsafe {
         std::mem::transmute::<(), Void>(())
     };
-    f(v); //~ inside call to `f`
+    f(v); //~ inside `main`
 }