Update rust toolchain to 1.91.1

.github/workflows/ubuntu_x86_64.yml

@@ -33,7 +33,7 @@ jobs:
         run: cargo run --locked --release format --check crates/compiler/builtins/roc
 
       - name: ensure there are no unused dependencies
-        run: cargo +nightly-2024-02-03 udeps --all-targets
+        run: cargo +nightly-2025-09-14 udeps --all-targets
 
       - name: zig wasm tests
         run: cd crates/compiler/builtins/bitcode && ./run-wasm-tests.sh
@@ -65,5 +65,5 @@ jobs:
 
       #- name: run fuzz tests - ok to merge if this one fails # for now!
       #  run: |
-      #    cargo +nightly-2024-02-03 install --locked cargo-fuzz
-      #    cd crates/compiler/test_syntax/fuzz && cargo +nightly-2024-02-03 fuzz run -j4 fuzz_expr --sanitizer=none -- -dict=dict.txt -max_total_time=60
+      #    cargo +nightly-2025-09-14 install --locked cargo-fuzz
+      #    cd crates/compiler/test_syntax/fuzz && cargo +nightly-2025-09-14 fuzz run -j4 fuzz_expr --sanitizer=none -- -dict=dict.txt -max_total_time=60

.github/workflows/windows_tests.yml

@@ -40,8 +40,8 @@ jobs:
           cd crates\compiler\builtins\bitcode\
           zig build test
 
-      - name: install rust nightly 1.77.0
-        run: rustup install nightly-2024-02-03
+      - name: install rust nightly 1.91.0
+        run: rustup install nightly-2025-09-14
 
       - name: set up llvm 18
         run: |

crates/cli/tests/platform-switching/rust-platform/rust-toolchain.toml

@@ -1,9 +1,9 @@
 [toolchain]
-channel = "1.77.2"
+channel = "1.91.1"
 
 profile = "default"
 
 components = [
     # for usages of rust-analyzer or similar tools inside `nix develop`
     "rust-src"
-]
+]

crates/compiler/build/src/link.rs

@@ -488,7 +488,7 @@ pub fn rebuild_host(
             // on windows, we need the nightly toolchain so we can use `-Z export-executable-symbols`
             // using `+nightly` only works when running cargo through rustup
             let mut cmd = rustup();
-            cmd.args(["run", "nightly-2024-02-03", "cargo"]);
+            cmd.args(["run", "nightly-2025-09-14", "cargo"]);
 
             cmd
         } else {

crates/repl_test/src/wasm.rs

@@ -5,7 +5,7 @@ use roc_wasm_interp::{
 };
 
 const COMPILER_BYTES: &[u8] =
-    include_bytes!("../../../target/wasm32-wasi/release-with-lto/roc_repl_wasm.wasm");
+    include_bytes!("../../../target/wasm32-wasip1/release-with-lto/roc_repl_wasm.wasm");
 
 struct CompilerDispatcher<'a> {
     arena: &'a Bump,

crates/repl_test/test_wasm.sh

@@ -6,10 +6,10 @@ set -euxo pipefail
 # If we ever decide to do that, one of the cargo processes will need to use the `--target-dir` option.
 
 # We need to clear RUSTFLAGS for this command, as CI sets normally some flags that are specific to CPU targets.
-# Tests target wasm32-wasi instead of wasm32-unknown-unknown, so that we can debug with println! and dbg
+# Tests target wasm32-wasip1 instead of wasm32-unknown-unknown, so that we can debug with println! and dbg
 # This has to be built with lto for now. If we do not use lto, it will pull in system calls we don't yet support.
 # TODO: Add system calls to our wasi interp so that this can just be built in release without lto.
-RUSTFLAGS="" cargo build --locked --profile release-with-lto --target wasm32-wasi -p roc_repl_wasm --no-default-features --features wasi_test
+RUSTFLAGS="" cargo build --locked --profile release-with-lto --target wasm32-wasip1 -p roc_repl_wasm --no-default-features --features wasi_test
 
 # Build & run the test code on *native* target, not WebAssembly
 cargo test --locked --release -p repl_test --features wasm $@

flake.nix

@@ -3,7 +3,7 @@
 
   inputs = {
     nixpkgs.url =
-      "github:nixos/nixpkgs?rev=184957277e885c06a505db112b35dfbec7c60494";
+      "github:nixos/nixpkgs?rev=50a96edd8d0db6cc8db57dab6bb6d6ee1f3dc49a";
 
     # rust from nixpkgs has some libc problems, this is patched in the rust-overlay
     rust-overlay = {

nix/compile-deps.nix

@@ -1,6 +1,6 @@
 { pkgs }:
 let
-  zigPkg = pkgs.zig;
+  zigPkg = pkgs.zig_0_13;
   llvmPkgs = pkgs.llvm_18;
   llvmVersion = builtins.splitVersion llvmPkgs.release_version;
   llvmMajorMinorStr = builtins.elemAt llvmVersion 0 + builtins.elemAt llvmVersion 1;

rust-toolchain.toml

@@ -1,26 +1,25 @@
 [toolchain]
 # How to update version:
 #  - update `channel = "RUST_VERSION"`
-#  - update `channel = "RUST_VERSION"` in examples/platform-switching/rust-platform/rust-toolchain.toml
-#  - update `channel = "RUST_VERSION"` in examples/glue/rust-platform/rust-toolchain.toml
+#  - update `channel = "RUST_VERSION"` in crates/cli/tests/platform-switching/rust-platform/rust-toolchain.toml
 #  - to update the nightly version:
-#     - Find the latest nightly release that matches RUST_VERSION here: https://github.com/oxalica/rust-overlay/tree/master/manifests/nightly/2024
+#     - Find the latest nightly release that matches RUST_VERSION here: https://github.com/oxalica/rust-overlay/tree/master/manifests/nightly/2025
 #     - update `channel = "nightly-OLD_DATE"` below
 #     - update nightly-OLD_DATE in .github/workflows/ubuntu_x86_64.yml
 #     - update nightly-OLD_DATE in .github/workflows/windows_tests.yml
 #     - update nightly-OLD_DATE in .github/workflows/windows_release_build.yml
 #     - update nightly-OLD_DATE in crates/compiler/build/src/link.rs
 
-channel = "1.77.2" # check ^^^ when changing this
+channel = "1.91.1" # check ^^^ when changing this
 # 
-# channel = "nightly-2024-02-03" # 1.77.0 nightly to be able to use unstable features
+# channel = "nightly-2025-09-14" # 1.91.0 nightly to be able to use unstable features
 profile = "default"
 components = [
     # for usages of rust-analyzer or similar tools inside `nix develop`
     "rust-src"
 ]
 
 targets = [
-    "wasm32-wasi", # for test_wasm.sh
+    "wasm32-wasip1", # for test_wasm.sh
     "wasm32-unknown-unknown", # for repl_wasm
 ]