diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 2032ce36e..78adcb7e4 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -49,7 +49,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly-2023-04-12
+          toolchain: nightly-2023-08-25
           components: rust-src, rustc-dev, llvm-tools-preview
           target: ${{ matrix.target }}
           profile: minimal
diff --git a/Cargo.toml b/Cargo.toml
index 042adeb9d..c54172a45 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,7 @@
 [workspace]
 members = ["crates/*"]
 exclude = ["ide/src/tests/mock_project"]
+resolver = "2"
 
 [profile.bench]
 debug = true
\ No newline at end of file
diff --git a/README.md b/README.md
index 4c2cd8878..d25fae98a 100644
--- a/README.md
+++ b/README.md
@@ -78,8 +78,8 @@ The documentation is published here: https://willcrichton.net/flowistry/flowistr
 
 ## Usage
 
-Note that the latest Flowistry has a [**Maximum** Supported Rust Version](https://github.com/cognitive-engineering-lab/rustc_plugin/tree/main#maximum-supported-rust-version) of **Rust 1.69**. 
-Flowistry is not guaranteed to work with features implemented after 1.69.
+Note that the latest Flowistry has a [**Maximum** Supported Rust Version](https://github.com/cognitive-engineering-lab/rustc_plugin/tree/main#maximum-supported-rust-version) of **Rust 1.73**. 
+Flowistry is not guaranteed to work with features implemented after 1.73.
 
 ### Startup
 
@@ -182,7 +182,7 @@ If rustup fails, especially with an error like "could not rename downloaded file
 To solve the issue, go to the command line and run:
 
 ```
-rustup toolchain install nightly-2023-04-12 -c rust-src -c rustc-dev -c llvm-tools-preview
+rustup toolchain install nightly-2023-08-25 -c rust-src -c rustc-dev -c llvm-tools-preview
 ```
 
 Then go back to VSCode and click "Continue" to let Flowistry continue installing.
diff --git a/crates/flowistry/Cargo.toml b/crates/flowistry/Cargo.toml
index a2beb93d6..4aed2265d 100644
--- a/crates/flowistry/Cargo.toml
+++ b/crates/flowistry/Cargo.toml
@@ -20,7 +20,7 @@ log = "0.4"
 fluid-let = "1.0"
 cfg-if = "1.0"
 serde = {version = "1", features = ["derive"]}
-rustc_utils = "0.6.3-nightly-2023-04-12"
+rustc_utils = "0.7.0-nightly-2023-08-25"
 
 # For local debugging
 html-escape = {version = "0.2", optional = true}
diff --git a/crates/flowistry/benches/main.rs b/crates/flowistry/benches/main.rs
index fe083adf5..5a1cb5d31 100644
--- a/crates/flowistry/benches/main.rs
+++ b/crates/flowistry/benches/main.rs
@@ -13,7 +13,7 @@ use criterion::{
 };
 use flowistry::infoflow::Direction;
 use glob::glob;
-use rustc_borrowck::BodyWithBorrowckFacts;
+use rustc_borrowck::consumers::BodyWithBorrowckFacts;
 use rustc_hir::{BodyId, ItemKind};
 use rustc_middle::{
   mir::{Location, Place},
diff --git a/crates/flowistry/examples/example.rs b/crates/flowistry/examples/example.rs
index c6362db6a..0efc3cd2f 100644
--- a/crates/flowistry/examples/example.rs
+++ b/crates/flowistry/examples/example.rs
@@ -25,7 +25,7 @@ extern crate rustc_span;
 use std::process::Command;
 
 use flowistry::{indexed::impls::LocationOrArg, infoflow::Direction};
-use rustc_borrowck::BodyWithBorrowckFacts;
+use rustc_borrowck::consumers::BodyWithBorrowckFacts;
 use rustc_hir::{BodyId, ItemKind};
 use rustc_middle::{
   mir::{Local, Place},
diff --git a/crates/flowistry/src/indexed/mod.rs b/crates/flowistry/src/indexed/mod.rs
index 1b26dfe79..f3c1e56a9 100644
--- a/crates/flowistry/src/indexed/mod.rs
+++ b/crates/flowistry/src/indexed/mod.rs
@@ -9,7 +9,7 @@
 //! Therefore if we want to encode a set of locations (e.g. for the [`FlowDomain`](crate::infoflow::FlowDomain)),
 //! then we can assign each `Location` a numeric index and use a compact bit-set instead of, say,
 //! a hash set. Concretely, this means:
-//! 1. Defining a type `LocationOrArgIndex` that implements the [`Idx`](rustc_index::vec::Idx) trait.
+//! 1. Defining a type `LocationOrArgIndex` that implements the [`Idx`](rustc_index::Idx) trait.
 //! 2. Creating a mapping ("domain") from `Location`s to `LocationOrArgIndex`.
 //! 3. Constructing a `LocationSet` out of a [`BitSet`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_index/bit_set/struct.BitSet.html)`<LocationOrArgIndex>`.
 //!
@@ -35,10 +35,7 @@ use std::{
 };
 
 use rustc_data_structures::fx::FxHashMap as HashMap;
-use rustc_index::{
-  bit_set::BitSet,
-  vec::{Idx, IndexVec},
-};
+use rustc_index::{bit_set::BitSet, Idx, IndexVec};
 use rustc_mir_dataflow::{fmt::DebugWithContext, JoinSemiLattice};
 
 pub mod impls;
diff --git a/crates/flowistry/src/infoflow/analysis.rs b/crates/flowistry/src/infoflow/analysis.rs
index 0d1ec3ab3..890bb3fd6 100644
--- a/crates/flowistry/src/infoflow/analysis.rs
+++ b/crates/flowistry/src/infoflow/analysis.rs
@@ -234,7 +234,7 @@ impl<'a, 'tcx> AnalysisDomain<'tcx> for FlowAnalysis<'a, 'tcx> {
 
 impl<'a, 'tcx> Analysis<'tcx> for FlowAnalysis<'a, 'tcx> {
   fn apply_statement_effect(
-    &self,
+    &mut self,
     state: &mut Self::Domain,
     statement: &Statement<'tcx>,
     location: Location,
@@ -245,30 +245,32 @@ impl<'a, 'tcx> Analysis<'tcx> for FlowAnalysis<'a, 'tcx> {
     .visit_statement(statement, location);
   }
 
-  fn apply_terminator_effect(
-    &self,
+  fn apply_terminator_effect<'mir>(
+    &mut self,
     state: &mut Self::Domain,
-    terminator: &Terminator<'tcx>,
+    terminator: &'mir Terminator<'tcx>,
     location: Location,
-  ) {
+  ) -> TerminatorEdges<'mir, 'tcx> {
     if matches!(terminator.kind, TerminatorKind::Call { .. })
       && is_extension_active(|mode| mode.context_mode == ContextMode::Recurse)
       && self.recurse_into_call(state, &terminator.kind, location)
     {
-      return;
+      return terminator.edges();
     }
 
     ModularMutationVisitor::new(&self.place_info, |_, mutations| {
       self.transfer_function(state, mutations, location)
     })
     .visit_terminator(terminator, location);
+
+    terminator.edges()
   }
 
   fn apply_call_return_effect(
-    &self,
+    &mut self,
     _state: &mut Self::Domain,
     _block: BasicBlock,
-    _return_places: rustc_mir_dataflow::CallReturnPlaces<'_, 'tcx>,
+    _return_places: CallReturnPlaces<'_, 'tcx>,
   ) {
   }
 }
diff --git a/crates/flowistry/src/infoflow/mod.rs b/crates/flowistry/src/infoflow/mod.rs
index e4480b37b..d18906feb 100644
--- a/crates/flowistry/src/infoflow/mod.rs
+++ b/crates/flowistry/src/infoflow/mod.rs
@@ -6,7 +6,7 @@
 use std::cell::RefCell;
 
 use log::debug;
-use rustc_borrowck::BodyWithBorrowckFacts;
+use rustc_borrowck::consumers::BodyWithBorrowckFacts;
 use rustc_hir::BodyId;
 use rustc_middle::ty::TyCtxt;
 use rustc_utils::{block_timer, BodyExt};
diff --git a/crates/flowistry/src/infoflow/recursive.rs b/crates/flowistry/src/infoflow/recursive.rs
index 62be72b01..1a51511e3 100644
--- a/crates/flowistry/src/infoflow/recursive.rs
+++ b/crates/flowistry/src/infoflow/recursive.rs
@@ -1,7 +1,7 @@
 use log::{debug, info};
 use rustc_middle::{
   mir::*,
-  ty::{subst::GenericArgKind, ClosureKind, TyKind},
+  ty::{ClosureKind, GenericArgKind, TyKind},
 };
 use rustc_mir_dataflow::JoinSemiLattice;
 use rustc_utils::{mir::borrowck_facts::get_body_with_borrowck_facts, PlaceExt};
diff --git a/crates/flowistry/src/mir/aliases.rs b/crates/flowistry/src/mir/aliases.rs
index e4a0e7708..a2b219166 100644
--- a/crates/flowistry/src/mir/aliases.rs
+++ b/crates/flowistry/src/mir/aliases.rs
@@ -12,7 +12,7 @@ use rustc_data_structures::{
 use rustc_hir::def_id::DefId;
 use rustc_index::{
   bit_set::{HybridBitSet, SparseBitMatrix},
-  vec::IndexVec,
+  IndexVec,
 };
 use rustc_middle::{
   mir::{visit::Visitor, *},
@@ -87,7 +87,7 @@ impl<'a, 'tcx> Aliases<'a, 'tcx> {
     let start = Instant::now();
     let body = &body_with_facts.body;
     let static_region = RegionVid::from_usize(0);
-    let subset_base = &body_with_facts.input_facts.subset_base;
+    let subset_base = &body_with_facts.input_facts.as_ref().unwrap().subset_base;
 
     let all_pointers = body
       .local_decls()
diff --git a/crates/flowistry/src/mir/engine.rs b/crates/flowistry/src/mir/engine.rs
index 6751ce450..bd7bc1444 100644
--- a/crates/flowistry/src/mir/engine.rs
+++ b/crates/flowistry/src/mir/engine.rs
@@ -15,7 +15,7 @@ use std::rc::Rc;
 
 use either::Either;
 use rustc_data_structures::{graph::WithSuccessors, work_queue::WorkQueue};
-use rustc_index::vec::IndexVec;
+use rustc_index::IndexVec;
 use rustc_middle::{
   mir::{traversal, Body, Location},
   ty::TyCtxt,
@@ -39,7 +39,7 @@ pub struct AnalysisResults<'tcx, A: Analysis<'tcx>> {
 impl<'tcx, A: Analysis<'tcx>> AnalysisResults<'tcx, A> {
   pub fn visit_reachable_with<'mir, V>(&self, body: &'mir Body<'tcx>, visitor: &mut V)
   where
-    V: ResultsVisitor<'mir, 'tcx, FlowState = A::Domain>,
+    V: ResultsVisitor<'mir, 'tcx, Self, FlowState = A::Domain>,
   {
     for (block, data) in traversal::reachable(body) {
       for statement_index in 0 ..= data.statements.len() {
@@ -51,17 +51,19 @@ impl<'tcx, A: Analysis<'tcx>> AnalysisResults<'tcx, A> {
         let state = &self.state[loc_index];
 
         if statement_index == 0 {
-          visitor.visit_block_start(state, data, block);
+          visitor.visit_block_start(self, state, data, block);
         }
 
         if statement_index == data.statements.len() {
           visitor.visit_terminator_after_primary_effect(
+            self,
             state,
             data.terminator(),
             location,
           )
         } else {
           visitor.visit_statement_after_primary_effect(
+            self,
             state,
             &data.statements[statement_index],
             location,
@@ -85,7 +87,7 @@ pub fn iterate_to_fixpoint<'tcx, A: Analysis<'tcx>>(
   _tcx: TyCtxt<'tcx>,
   body: &Body<'tcx>,
   location_domain: Rc<LocationOrArgDomain>,
-  analysis: A,
+  mut analysis: A,
 ) -> AnalysisResults<'tcx, A> {
   let bottom_value = analysis.bottom_value(body);
 
diff --git a/crates/flowistry/src/mir/placeinfo.rs b/crates/flowistry/src/mir/placeinfo.rs
index b546c4c51..bb09ac721 100644
--- a/crates/flowistry/src/mir/placeinfo.rs
+++ b/crates/flowistry/src/mir/placeinfo.rs
@@ -144,9 +144,7 @@ impl<'a, 'tcx> PlaceInfo<'a, 'tcx> {
   fn collect_loans(&self, ty: Ty<'tcx>, mutability: Mutability) -> PlaceSet<'tcx> {
     let mut collector = LoanCollector {
       aliases: &self.aliases,
-      unknown_region: self
-        .tcx
-        .mk_region_from_kind(RegionKind::ReVar(UNKNOWN_REGION)),
+      unknown_region: Region::new_var(self.tcx, UNKNOWN_REGION),
       target_mutability: mutability,
       stack: vec![],
       loans: PlaceSet::default(),
diff --git a/crates/flowistry/src/test_utils.rs b/crates/flowistry/src/test_utils.rs
index dad04a165..069ca00c5 100644
--- a/crates/flowistry/src/test_utils.rs
+++ b/crates/flowistry/src/test_utils.rs
@@ -5,7 +5,7 @@ use std::{fs, io, panic, path::Path};
 use anyhow::Result;
 use fluid_let::fluid_set;
 use log::info;
-use rustc_borrowck::BodyWithBorrowckFacts;
+use rustc_borrowck::consumers::BodyWithBorrowckFacts;
 use rustc_data_structures::fx::FxHashSet as HashSet;
 use rustc_hir::BodyId;
 use rustc_middle::ty::TyCtxt;
@@ -14,7 +14,7 @@ pub use rustc_utils::test_utils::{compare_ranges, fmt_ranges, parse_ranges};
 use rustc_utils::{
   mir::borrowck_facts,
   source_map::{
-    range::{ByteRange, ToSpan},
+    range::{ByteRange, CharPos, ToSpan},
     spanner::Spanner,
   },
   test_utils,
@@ -57,15 +57,18 @@ pub fn bless(
       [("`[", char_range.start), ("]`", char_range.end)]
     })
     .collect::<Vec<_>>();
-  delims.sort_by_key(|(_, i)| i.0);
+  delims.sort_by_key(|(_, i)| (i.line, i.column));
 
   let mut output = String::new();
-  for (i, g) in contents.chars().enumerate() {
-    while delims.len() > 0 && delims[0].1 .0 == i {
-      let (delim, _) = delims.remove(0);
-      output.push_str(delim);
+  for (line, line_str) in contents.lines().enumerate() {
+    for (column, chr) in line_str.chars().enumerate() {
+      while delims.len() > 0 && delims[0].1 == (CharPos { line, column }) {
+        let (delim, _) = delims.remove(0);
+        output.push_str(delim);
+      }
+      output.push(chr);
     }
-    output.push(g);
+    output.push('\n');
   }
 
   fs::write(path.with_extension("txt.expected"), output)?;
diff --git a/crates/flowistry_ide/Cargo.toml b/crates/flowistry_ide/Cargo.toml
index e535412bc..d72e6c91c 100644
--- a/crates/flowistry_ide/Cargo.toml
+++ b/crates/flowistry_ide/Cargo.toml
@@ -24,8 +24,8 @@ serde = {version = "1", features = ["derive"]}
 serde_json = "1"
 flate2 = "1"
 base64 = "0.21"
-rustc_utils = {version = "0.6.3-nightly-2023-04-12", features = ["serde"]}
-rustc_plugin = "0.6.3-nightly-2023-04-12"
+rustc_utils = {version = "0.7.0-nightly-2023-08-25", features = ["serde"]}
+rustc_plugin = "0.7.0-nightly-2023-08-25"
 
 # Decompose
 petgraph = {version = "0.6", default-features = false, optional = true}
@@ -33,4 +33,4 @@ rayon = {version = "1.5", optional = true}
 
 # For binaries
 env_logger = {version = "0.9", default-features = false}
-clap = {version = "4", default-features = false, features = ["std", "derive"]}
\ No newline at end of file
+clap = {version = "4.4", default-features = false, features = ["std", "derive"]}
\ No newline at end of file
diff --git a/crates/flowistry_ide/README.md b/crates/flowistry_ide/README.md
index 4ff685568..1f6775d96 100644
--- a/crates/flowistry_ide/README.md
+++ b/crates/flowistry_ide/README.md
@@ -108,9 +108,9 @@ If rustup fails, especially with an error like "could not rename downloaded file
 To solve the issue, go to the command line and run:
 
 ```
-rustup toolchain install nightly-2023-04-12 -c rust-src -c rustc-dev -c llvm-tools-preview
+rustup toolchain install nightly-2023-08-25 -c rust-src -c rustc-dev -c llvm-tools-preview
 ```
 
-> Note: double check the value of "channel" in `rust-toolchain.toml` if `nightly-2023-04-12` is no longer correct.
+> Note: double check the value of "channel" in `rust-toolchain.toml` if `nightly-2023-08-25` is no longer correct.
 
 Then go back to VSCode and click "Continue" to let Flowistry continue installing.
diff --git a/crates/flowistry_ide/src/focus/mod.rs b/crates/flowistry_ide/src/focus/mod.rs
index 2bf5e9a45..bfa436771 100644
--- a/crates/flowistry_ide/src/focus/mod.rs
+++ b/crates/flowistry_ide/src/focus/mod.rs
@@ -93,6 +93,8 @@ pub fn focus(tcx: TyCtxt, body_id: BodyId) -> Result<FocusOutput> {
           .collect::<Vec<_>>()
       };
 
+      log::debug!("{:#?}", to_ranges(slice.clone()));
+
       Some(PlaceInfo {
         range: CharRange::from_span(mir_span.span(), source_map).ok()?,
         ranges: to_ranges(vec![mir_span.span()]),
diff --git a/crates/flowistry_ide/src/playground.rs b/crates/flowistry_ide/src/playground.rs
index bdf476e18..4ef98e89d 100644
--- a/crates/flowistry_ide/src/playground.rs
+++ b/crates/flowistry_ide/src/playground.rs
@@ -17,9 +17,8 @@ pub fn playground(tcx: TyCtxt, body_id: BodyId) -> Result<PlaygroundOutput> {
   let body = &body_with_facts.body;
   debug!("{}", body.to_string(tcx).unwrap());
 
-  let outlives = body_with_facts
-    .input_facts
-    .subset_base
+  let subset_base = &body_with_facts.input_facts.as_ref().unwrap().subset_base;
+  let outlives = subset_base
     .iter()
     .map(|(sup, sub, _)| (format!("{sup:?}"), format!("{sub:?}")))
     .collect::<HashSet<_>>();
diff --git a/crates/flowistry_ide/src/plugin.rs b/crates/flowistry_ide/src/plugin.rs
index 3775b5837..0ebc7c238 100644
--- a/crates/flowistry_ide/src/plugin.rs
+++ b/crates/flowistry_ide/src/plugin.rs
@@ -18,6 +18,7 @@ use rustc_hir::BodyId;
 use rustc_interface::interface::Result as RustcResult;
 use rustc_middle::ty::TyCtxt;
 use rustc_plugin::{CrateFilter, RustcPlugin, RustcPluginArgs, Utf8Path};
+use rustc_span::ErrorGuaranteed;
 use rustc_utils::{
   mir::borrowck_facts,
   source_map::{
@@ -53,7 +54,8 @@ enum FlowistryCommand {
 
   Focus {
     file: String,
-    pos: usize,
+    pos_line: usize,
+    pos_column: usize,
   },
 
   Decompose {
@@ -63,8 +65,10 @@ enum FlowistryCommand {
 
   Playground {
     file: String,
-    start: usize,
-    end: usize,
+    start_line: usize,
+    start_column: usize,
+    end_line: usize,
+    end_column: usize,
   },
 
   Preload,
@@ -141,11 +145,22 @@ impl RustcPlugin for FlowistryPlugin {
     match plugin_args.command {
       Spans { file, .. } => postprocess(crate::spans::spans(&compiler_args, file)),
       Playground {
-        file, start, end, ..
+        file,
+        start_line,
+        start_column,
+        end_line,
+        end_column,
+        ..
       } => {
         let compute_target = || CharRange {
-          start: CharPos(start),
-          end: CharPos(end),
+          start: CharPos {
+            line: start_line,
+            column: start_column,
+          },
+          end: CharPos {
+            line: end_line,
+            column: end_column,
+          },
           filename: Filename::intern(&file),
         };
         postprocess(run(
@@ -154,13 +169,23 @@ impl RustcPlugin for FlowistryPlugin {
           &compiler_args,
         ))
       }
-      Focus { file, pos, .. } => {
+      Focus {
+        file,
+        pos_line,
+        pos_column,
+        ..
+      } => {
         let compute_target = || {
+          let cpos = CharPos {
+            line: pos_line,
+            column: pos_column,
+          };
           let range = CharRange {
-            start: CharPos(pos),
-            end: CharPos(pos),
+            start: cpos,
+            end: cpos,
             filename: Filename::intern(&file),
           };
+          debug!("eyo WTF {range:?} {file}");
           FunctionIdentifier::Range(range)
         };
         postprocess(run(crate::focus::focus, compute_target, &compiler_args))
@@ -194,9 +219,7 @@ fn postprocess<T: Serialize>(result: FlowistryResult<T>) -> RustcResult<()> {
   let result = match result {
     Ok(output) => Ok(output),
     Err(e) => match e {
-      FlowistryError::BuildError => {
-        return Err(rustc_errors::ErrorGuaranteed::unchecked_claim_error_was_emitted());
-      }
+      FlowistryError::BuildError(e) => return Err(e),
       e => Err(e),
     },
   };
@@ -225,7 +248,7 @@ pub fn run_with_callbacks(
   );
 
   let compiler = rustc_driver::RunCompiler::new(&args, callbacks);
-  compiler.run().map_err(|_| FlowistryError::BuildError)
+  compiler.run().map_err(FlowistryError::BuildError)
 }
 
 fn run<A: FlowistryAnalysis, T: ToSpan>(
@@ -257,7 +280,7 @@ fn run<A: FlowistryAnalysis, T: ToSpan>(
 #[derive(Debug, Serialize)]
 #[serde(tag = "type")]
 pub enum FlowistryError {
-  BuildError,
+  BuildError(#[serde(skip_serializing)] ErrorGuaranteed),
   AnalysisError { error: String },
   FileNotFound,
 }
@@ -312,6 +335,7 @@ impl<A: FlowistryAnalysis, T: ToSpan, F: FnOnce() -> T> rustc_driver::Callbacks
       let mut analysis = self.analysis.take().unwrap();
       self.output = Some((|| {
         let target = (self.compute_target.take().unwrap())().to_span(tcx)?;
+        debug!("target span: {target:?}");
         let mut bodies = find_enclosing_bodies(tcx, target);
         let body = bodies.next().context("Selection did not map to a body")?;
         analysis.analyze(tcx, body)
diff --git a/crates/flowistry_ide/src/spans.rs b/crates/flowistry_ide/src/spans.rs
index 4c33c5841..aa2a82e2d 100644
--- a/crates/flowistry_ide/src/spans.rs
+++ b/crates/flowistry_ide/src/spans.rs
@@ -1,5 +1,5 @@
 use rustc_utils::source_map::{
-  filename::Filename, find_bodies::find_bodies, range::ByteRange,
+  filename::Filename, find_bodies::find_bodies, range::CharRange,
 };
 use serde::Serialize;
 
@@ -7,7 +7,7 @@ use crate::plugin::{FlowistryError, FlowistryResult};
 
 #[derive(Serialize)]
 pub struct SpansOutput {
-  spans: Vec<ByteRange>,
+  spans: Vec<CharRange>,
 }
 
 unsafe impl Send for SpansOutput {}
@@ -37,7 +37,7 @@ impl rustc_driver::Callbacks for Callbacks {
           .filter(|span| {
             source_map.lookup_source_file(span.lo()).name_hash == source_file.name_hash
           })
-          .filter_map(|span| ByteRange::from_span(span, source_map).ok())
+          .filter_map(|span| CharRange::from_span(span, source_map).ok())
           .collect::<Vec<_>>();
         Ok(SpansOutput { spans })
       })());
diff --git a/crates/flowistry_ifc/Cargo.toml b/crates/flowistry_ifc/Cargo.toml
index 0e4aa328d..07dc26055 100644
--- a/crates/flowistry_ifc/Cargo.toml
+++ b/crates/flowistry_ifc/Cargo.toml
@@ -13,5 +13,5 @@ env_logger = "0.9"
 termcolor = "1.1"
 anyhow = "1"
 log = "0.4"
-rustc_plugin = "0.6.3-nightly-2023-04-12"
-rustc_utils = "0.6.3-nightly-2023-04-12"
\ No newline at end of file
+rustc_plugin = "0.7.0-nightly-2023-08-25"
+rustc_utils = "0.7.0-nightly-2023-08-25"
\ No newline at end of file
diff --git a/ide/src/decorations.ts b/ide/src/decorations.ts
index 8d404f176..8c99517e3 100644
--- a/ide/src/decorations.ts
+++ b/ide/src/decorations.ts
@@ -1,7 +1,13 @@
 import _ from "lodash";
 import * as vscode from "vscode";
 
-import { Range, to_vsc_range } from "./range";
+import {
+  Interval,
+  Range,
+  interval_to_range,
+  range_to_interval,
+  to_vsc_range,
+} from "./range";
 
 export let highlight_type = vscode.window.createTextEditorDecorationType({
   backgroundColor: new vscode.ThemeColor("editor.symbolHighlightBackground"),
@@ -33,38 +39,36 @@ export let select_type = vscode.window.createTextEditorDecorationType({
   },
 });
 
-export let invert_ranges = (container: Range, pieces: Range[]): Range[] => {
+export let invert_ranges = (
+  container: Range,
+  pieces: Range[],
+  doc: vscode.TextDocument
+): Range[] => {
+  let icontainer = range_to_interval(container, doc);
+  let ipieces = pieces.map((piece) => range_to_interval(piece, doc));
+
   let filename = container.filename;
-  let pieces_sorted = _.sortBy(pieces, (r) => r.start).filter(
-    (r) =>
-      container.start <= r.start && r.end <= container.end
+  let pieces_sorted = _.sortBy(ipieces, (r) => r[0]).filter(
+    (r) => icontainer[0] <= r[0] && r[1] <= icontainer[1]
   );
 
-  let new_ranges: Range[] = [];
-  let start = container.start;
+  let new_ranges: Interval[] = [];
+  let start = icontainer[0];
   pieces_sorted.forEach((r) => {
-    if (r.start < start) {
-      start = Math.max(r.end, start);
+    if (r[0] < start) {
+      start = Math.max(r[1], start);
       return;
     }
 
-    let end = r.start;
-    new_ranges.push({
-      start: start,
-      end: end,
-      filename,
-    });
+    let end = r[0];
+    new_ranges.push([start, end]);
 
-    start = Math.max(start, r.end);
+    start = Math.max(start, r[1]);
   });
 
-  new_ranges.push({
-    start: start,
-    end: container.end,
-    filename,
-  });
+  new_ranges.push([start, icontainer[1]]);
 
-  return new_ranges;
+  return new_ranges.map((intvl) => interval_to_range(intvl, filename, doc));
 };
 
 export let highlight_slice = (
@@ -76,7 +80,7 @@ export let highlight_slice = (
 ) => {
   highlight_ranges(seeds, editor, select_type);
   let hide_ranges = containers
-    .map((container) => invert_ranges(container, slice))
+    .map((container) => invert_ranges(container, slice, editor.document))
     .flat();
   highlight_ranges(hide_ranges, editor, hide_type);
   highlight_ranges(slice, editor, slice_type);
@@ -90,7 +94,7 @@ export function highlight_ranges(
 ) {
   editor.setDecorations(
     type,
-    ranges.map((range) => to_vsc_range(range, editor.document))
+    ranges.map((range) => to_vsc_range(range))
   );
 }
 
diff --git a/ide/src/focus.ts b/ide/src/focus.ts
index 325aab270..1d9cade51 100644
--- a/ide/src/focus.ts
+++ b/ide/src/focus.ts
@@ -29,11 +29,12 @@ class FocusBodyState {
   focus: Focus;
   places: RangeTree<PlaceInfo>;
 
-  constructor(focus: Focus) {
+  constructor(focus: Focus, doc: vscode.TextDocument) {
     this.mark = null;
     this.focus = focus;
     this.places = new RangeTree(
-      focus.place_info.map((info) => ({ range: info.range, value: info }))
+      focus.place_info.map((info) => ({ range: info.range, value: info })),
+      doc
     );
   }
 
@@ -44,15 +45,17 @@ class FocusBodyState {
     let cmd = [
       "focus",
       doc.fileName,
-      doc.offsetAt(selection.anchor).toString(),
+      selection.anchor.line.toString(),
+      selection.anchor.character.toString(),
     ];
     let focus_res = await globals.call_flowistry<Focus>(cmd);
+    console.log(focus_res);
 
     if (!is_ok(focus_res)) {
       return focus_res;
     }
 
-    return ok(new FocusBodyState(focus_res.value));
+    return ok(new FocusBodyState(focus_res.value, doc));
   };
 
   private find_slice_at_selection = (
@@ -60,7 +63,6 @@ class FocusBodyState {
     doc: vscode.TextDocument
   ): { seeds: Range[]; slice: Range[]; direct_influence: Range[] } => {
     let query = this.places.selection_to_interval(
-      doc,
       this.mark || editor.selection
     );
     let result = this.places.search(query);
@@ -92,7 +94,7 @@ class FocusBodyState {
     if (seeds.length > 0) {
       if (select) {
         editor.selections = slice.map((range) => {
-          let vsc_range = to_vsc_range(range, doc);
+          let vsc_range = to_vsc_range(range);
           return new vscode.Selection(vsc_range.start, vsc_range.end);
         });
       } else {
@@ -131,9 +133,10 @@ class FocusDocumentState {
   // vscode.TextEditor to reduce API complexity. But those references were
   // seemingly invalidated after changing documents, so the editor must be
   // passed in anew each time.
-  constructor(spans: Spans) {
+  constructor(spans: Spans, doc: vscode.TextDocument) {
     this.bodies = new RangeTree(
-      spans.spans.map((range) => ({ range, value: new Cell(null) }))
+      spans.spans.map((range) => ({ range, value: new Cell(null) })),
+      doc
     );
   }
 
@@ -142,11 +145,12 @@ class FocusDocumentState {
   ): Promise<FlowistryResult<FocusDocumentState>> => {
     let cmd = ["spans", editor.document.fileName];
     let spans = await globals.call_flowistry<Spans>(cmd);
+    console.log("spans", spans);
     if (!is_ok(spans)) {
       return spans;
     }
 
-    return ok(new FocusDocumentState(spans.value));
+    return ok(new FocusDocumentState(spans.value, editor.document));
   };
 
   on_change_selection = async (
@@ -171,7 +175,7 @@ class FocusDocumentState {
   ): Promise<FlowistryResult<FocusBodyState> | null> => {
     // Find all bodies that contain the user's selection.
     let result = this.bodies.search(
-      this.bodies.selection_to_interval(editor.document, editor.selection)
+      this.bodies.selection_to_interval(editor.selection)
     );
 
     // If the user hasn't selected a body, then return null
@@ -346,7 +350,10 @@ export class FocusMode {
     }
   };
 
-  private handle_analysis_result = async <T>(result: FlowistryResult<T>, userActivated: boolean = false) => {
+  private handle_analysis_result = async <T>(
+    result: FlowistryResult<T>,
+    userActivated: boolean = false
+  ) => {
     if (!is_ok(result)) {
       if (userActivated) await show_error(result);
       this.set_mode("error");
diff --git a/ide/src/range.ts b/ide/src/range.ts
index 2d614e2ab..e96c86054 100644
--- a/ide/src/range.ts
+++ b/ide/src/range.ts
@@ -2,22 +2,48 @@ import IntervalTree from "@flatten-js/interval-tree";
 import _ from "lodash";
 import vscode from "vscode";
 
+export interface CharPos {
+  line: number;
+  column: number;
+}
+
 export interface Range {
-  start: number;
-  end: number;
+  start: CharPos;
+  end: CharPos;
   filename: string;
 }
 
-export let to_vsc_range = (
-  range: Range,
-  doc: vscode.TextDocument
-): vscode.Range =>
+export let to_vsc_range = (range: Range): vscode.Range =>
   new vscode.Range(
-    doc.positionAt(range.start),
-    doc.positionAt(range.end)
+    range.start.line,
+    range.start.column,
+    range.end.line,
+    range.end.column
   );
 
-type Interval = [number, number];
+export let range_to_interval = (
+  range: Range,
+  doc: vscode.TextDocument
+): Interval => {
+  let vsc_range = to_vsc_range(range);
+  return [doc.offsetAt(vsc_range.start), doc.offsetAt(vsc_range.end)];
+};
+
+export let interval_to_range = (
+  interval: Interval,
+  filename: string,
+  doc: vscode.TextDocument
+): Range => {
+  let start = doc.positionAt(interval[0]);
+  let end = doc.positionAt(interval[1]);
+  return {
+    start: { line: start.line, column: start.character },
+    end: { line: end.line, column: end.character },
+    filename,
+  };
+};
+
+export type Interval = [number, number];
 
 export type Ranged<T> = {
   range: Range;
@@ -31,27 +57,31 @@ export interface SearchResult<T> {
 
 export class RangeTree<T> {
   tree: IntervalTree<T>;
+  filename: string;
 
-  constructor(entries: Ranged<T>[] = []) {
+  constructor(entries: Ranged<T>[] = [], readonly doc: vscode.TextDocument) {
     this.tree = new IntervalTree();
+    this.filename = entries.length > 0 ? entries[0].range.filename : "";
     entries.forEach(({ range, value }) => {
       this.insert(range, value);
     });
   }
 
-  range_to_interval(range: Range): Interval {
-    return [range.start, range.end];
-  }
-
-  selection_to_interval(
-    doc: vscode.TextDocument,
-    selection: vscode.Selection
-  ): Interval {
-    return [doc.offsetAt(selection.start), doc.offsetAt(selection.end)];
+  selection_to_interval(selection: vscode.Selection): Interval {
+    return [
+      this.doc.offsetAt(selection.start),
+      this.doc.offsetAt(selection.end),
+    ];
   }
 
   insert(range: Range, data: T) {
-    this.tree.insert(this.range_to_interval(range), data);
+    console.log(
+      "Inserting range",
+      range,
+      "at interval",
+      range_to_interval(range, this.doc)
+    );
+    this.tree.insert(range_to_interval(range, this.doc), data);
   }
 
   search(query: Interval): SearchResult<T> {
@@ -70,11 +100,7 @@ export class RangeTree<T> {
     };
 
     result.forEach(([interval, value]) => {
-      let range = {
-        start: interval[0],
-        end: interval[1],
-        filename: "",
-      };
+      let range = interval_to_range(interval, this.filename, this.doc);
       if (is_contained(interval, query)) {
         final.contained.push({ range, value });
       } else if (is_contained(query, interval)) {
@@ -86,12 +112,11 @@ export class RangeTree<T> {
 
     ["contained", "containing", "overlapping"].forEach((k) => {
       let final_ = final as any;
-      final_[k] = _.sortBy(
-        final_[k],
-        ({ range }) => range.end - range.start
-      );
+      final_[k] = _.sortBy(final_[k], ({ range }) => range.end - range.start);
     });
 
+    console.log("Querying", query, "for result", final);
+
     return final;
   }
 }
diff --git a/ide/src/tests/commands/util/helpers.ts b/ide/src/tests/commands/util/helpers.ts
index 8a190686d..0c824a160 100644
--- a/ide/src/tests/commands/util/helpers.ts
+++ b/ide/src/tests/commands/util/helpers.ts
@@ -119,9 +119,7 @@ export const get_command_selections = async (
 
   const unique_ranges = _.uniqWith(output_data.ranges, _.isEqual);
   const sorted_ranges = _.sortBy(unique_ranges, (range) => [range.start]);
-  const vscode_ranges = sorted_ranges.map((range) =>
-    to_vsc_range(range, vscode.window.activeTextEditor?.document!)
-  );
+  const vscode_ranges = sorted_ranges.map((range) => to_vsc_range(range));
   const merged_ranges = merge_ranges(vscode_ranges);
   const expected_selections = merged_ranges.map(
     (range) => new vscode.Selection(range.start, range.end)
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index a9dabd650..d9d396bd2 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2023-04-12"
+channel = "nightly-2023-08-25"
 components = ["rust-src", "rustc-dev", "llvm-tools-preview"]
\ No newline at end of file