From 3e735a52febb098e1b541e89a6653adbcb134760 Mon Sep 17 00:00:00 2001
From: Smitty <me@smitop.com>
Date: Fri, 18 Jun 2021 17:33:33 -0400
Subject: [PATCH] Unwrap allocated Location at creation

---
 compiler/rustc_mir/src/const_eval/mod.rs          |  6 +-----
 compiler/rustc_mir/src/interpret/intrinsics.rs    |  2 +-
 .../src/interpret/intrinsics/caller_location.rs   | 15 +++++++--------
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/compiler/rustc_mir/src/const_eval/mod.rs b/compiler/rustc_mir/src/const_eval/mod.rs
index 8e379f9eb283..6a514e9f62fc 100644
--- a/compiler/rustc_mir/src/const_eval/mod.rs
+++ b/compiler/rustc_mir/src/const_eval/mod.rs
@@ -31,11 +31,7 @@ pub(crate) fn const_caller_location(
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::reveal_all(), false);
 
-    // This can fail if rustc runs out of memory right here. Trying to emit an error would be
-    // pointless, since that would require allocating more memory than a Location.
-    let loc_place = ecx
-        .alloc_caller_location(file, line, col)
-        .expect("not enough memory to allocate location?");
+    let loc_place = ecx.alloc_caller_location(file, line, col);
     if intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &loc_place).is_err() {
         bug!("intern_const_alloc_recursive should not error in this case")
     }
diff --git a/compiler/rustc_mir/src/interpret/intrinsics.rs b/compiler/rustc_mir/src/interpret/intrinsics.rs
index 92484054e86a..4e4166dad50e 100644
--- a/compiler/rustc_mir/src/interpret/intrinsics.rs
+++ b/compiler/rustc_mir/src/interpret/intrinsics.rs
@@ -137,7 +137,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match intrinsic_name {
             sym::caller_location => {
                 let span = self.find_closest_untracked_caller_location();
-                let location = self.alloc_caller_location_for_span(span)?;
+                let location = self.alloc_caller_location_for_span(span);
                 self.write_scalar(location.ptr, dest)?;
             }
 
diff --git a/compiler/rustc_mir/src/interpret/intrinsics/caller_location.rs b/compiler/rustc_mir/src/interpret/intrinsics/caller_location.rs
index d3e3a565adaf..4a3278030b5d 100644
--- a/compiler/rustc_mir/src/interpret/intrinsics/caller_location.rs
+++ b/compiler/rustc_mir/src/interpret/intrinsics/caller_location.rs
@@ -9,7 +9,7 @@ use rustc_target::abi::LayoutOf;
 
 use crate::interpret::{
     intrinsics::{InterpCx, Machine},
-    InterpResult, MPlaceTy, MemoryKind, Scalar,
+    MPlaceTy, MemoryKind, Scalar,
 };
 
 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@@ -79,7 +79,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         filename: Symbol,
         line: u32,
         col: u32,
-    ) -> InterpResult<'static, MPlaceTy<'tcx, M::PointerTag>> {
+    ) -> MPlaceTy<'tcx, M::PointerTag> {
         let file =
             self.allocate_str(&filename.as_str(), MemoryKind::CallerLocation, Mutability::Not);
         let line = Scalar::from_u32(line);
@@ -91,7 +91,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             .type_of(self.tcx.require_lang_item(LangItem::PanicLocation, None))
             .subst(*self.tcx, self.tcx.mk_substs([self.tcx.lifetimes.re_erased.into()].iter()));
         let loc_layout = self.layout_of(loc_ty).unwrap();
-        let location = self.allocate(loc_layout, MemoryKind::CallerLocation)?;
+        // This can fail if rustc runs out of memory right here. Trying to emit an error would be
+        // pointless, since that would require allocating more memory than a Location.
+        let location = self.allocate(loc_layout, MemoryKind::CallerLocation).unwrap();
 
         // Initialize fields.
         self.write_immediate(file.to_ref(), &self.mplace_field(&location, 0).unwrap().into())
@@ -101,7 +103,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         self.write_scalar(col, &self.mplace_field(&location, 2).unwrap().into())
             .expect("writing to memory we just allocated cannot fail");
 
-        Ok(location)
+        location
     }
 
     crate fn location_triple_for_span(&self, span: Span) -> (Symbol, u32, u32) {
@@ -114,10 +116,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         )
     }
 
-    pub fn alloc_caller_location_for_span(
-        &mut self,
-        span: Span,
-    ) -> InterpResult<'static, MPlaceTy<'tcx, M::PointerTag>> {
+    pub fn alloc_caller_location_for_span(&mut self, span: Span) -> MPlaceTy<'tcx, M::PointerTag> {
         let (file, line, column) = self.location_triple_for_span(span);
         self.alloc_caller_location(file, line, column)
     }