Update to nightly-2025-07-28.

- `run_fat_lto`, `optimize_fat`, and `autodiff` were merged into
  `run_and_optimize_fat_lto`, and the parameters were changed.
- `run_thin_lto` parameters were changed.
- `codegen` parameters were changed.
- `LtoModuleCodegen` was removed.

The LTO changes occurred in rust-lang/rust PR 143388 and PR 144062.

Author: nnethercote

crates/rustc_codegen_spirv/build.rs

@@ -18,9 +18,9 @@ use std::{env, fs, mem};
 /// `cargo publish`. We need to figure out a way to do this properly, but let's hardcode it for now :/
 //const REQUIRED_RUST_TOOLCHAIN: &str = include_str!("../../rust-toolchain.toml");
 const REQUIRED_RUST_TOOLCHAIN: &str = r#"[toolchain]
-channel = "nightly-2025-07-14"
+channel = "nightly-2025-07-28"
 components = ["rust-src", "rustc-dev", "llvm-tools"]
-# commit_hash = e9182f195b8505c87c4bd055b9f6e114ccda0981"#;
+# commit_hash = f8e355c230c6eb7b78ffce6a92fd81f78c890524"#;
 
 fn rustc_output(arg: &str) -> Result<String, Box<dyn Error>> {
     let rustc = env::var("RUSTC").unwrap_or_else(|_| "rustc".into());

crates/rustc_codegen_spirv/src/lib.rs

@@ -141,7 +141,7 @@ mod target_feature;
 
 use builder::Builder;
 use codegen_cx::CodegenCx;
-use maybe_pqp_cg_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
+use maybe_pqp_cg_ssa::back::lto::{SerializedModule, ThinModule};
 use maybe_pqp_cg_ssa::back::write::{
     CodegenContext, FatLtoInput, ModuleConfig, OngoingCodegen, TargetMachineFactoryConfig,
 };
@@ -170,7 +170,7 @@ use std::any::Any;
 use std::fs;
 use std::io::Cursor;
 use std::io::Write;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use tracing::{error, warn};
 
@@ -333,7 +333,7 @@ impl WriteBackendMethods for SpirvCodegenBackend {
     type ThinBuffer = SpirvModuleBuffer;
 
     // FIXME(eddyb) reuse the "merge" stage of `crate::linker` for this, or even
-    // delegate to `run_fat_lto` (although `-Zcombine-cgu` is much more niche).
+    // delegate to `run_and_optimize_fat_lto` (although `-Zcombine-cgu` is much more niche).
     fn run_link(
         cgcx: &CodegenContext<Self>,
         diag_handler: DiagCtxtHandle<'_>,
@@ -351,24 +351,29 @@ impl WriteBackendMethods for SpirvCodegenBackend {
     // consider setting `requires_lto = true` in the target specs and moving the
     // entirety of `crate::linker` into this stage (lacking diagnostics may be
     // an issue - it's surprising `CodegenBackend::link` has `Session` at all).
-    fn run_fat_lto(
+    fn run_and_optimize_fat_lto(
         cgcx: &CodegenContext<Self>,
+        _exported_symbols_for_lto: &[String],
+        _each_linked_rlib_for_lto: &[PathBuf],
         _modules: Vec<FatLtoInput<Self>>,
-        _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<LtoModuleCodegen<Self>, FatalError> {
+        _diff_fncs: Vec<AutoDiffItem>,
+    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
         assert!(
             cgcx.lto == rustc_session::config::Lto::Fat,
-            "`run_fat_lto` (for `WorkItemResult::NeedsFatLto`) should \
+            "`run_and_optimize_fat_lto` (for `WorkItemResult::NeedsFatLto`) should \
              only be invoked due to `-Clto` (or equivalent)"
         );
         unreachable!("Rust-GPU does not support fat LTO")
     }
 
     fn run_thin_lto(
         cgcx: &CodegenContext<Self>,
+        // FIXME(bjorn3): Limit LTO exports to these symbols
+        _exported_symbols_for_lto: &[String],
+        _each_linked_rlib_for_lto: &[PathBuf], // njn: ?
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError> {
+    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
         link::run_thin(cgcx, modules, cached_modules)
     }
 
@@ -409,16 +414,8 @@ impl WriteBackendMethods for SpirvCodegenBackend {
         Ok(module)
     }
 
-    fn optimize_fat(
-        cgcx: &CodegenContext<Self>,
-        module: &mut ModuleCodegen<Self::Module>,
-    ) -> Result<(), FatalError> {
-        Self::optimize_common(cgcx, module)
-    }
-
     fn codegen(
         cgcx: &CodegenContext<Self>,
-        _diag_handler: DiagCtxtHandle<'_>,
         module: ModuleCodegen<Self::Module>,
         _config: &ModuleConfig,
     ) -> Result<CompiledModule, FatalError> {
@@ -457,15 +454,6 @@ impl WriteBackendMethods for SpirvCodegenBackend {
             SpirvModuleBuffer(module.module_llvm.assemble()),
         )
     }
-
-    fn autodiff(
-        _cgcx: &CodegenContext<Self>,
-        _module: &ModuleCodegen<Self::Module>,
-        _diff_fncs: Vec<AutoDiffItem>,
-        _config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
-        unreachable!("Rust-GPU does not support autodiff")
-    }
 }
 
 impl ExtraBackendMethods for SpirvCodegenBackend {

crates/rustc_codegen_spirv/src/link.rs

@@ -8,7 +8,7 @@ use rspirv::binary::Assemble;
 use rspirv::dr::Module;
 use rustc_ast::CRATE_NODE_ID;
 use rustc_codegen_spirv_types::{CompileResult, ModuleResult};
-use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule, ThinShared};
+use rustc_codegen_ssa::back::lto::{SerializedModule, ThinModule, ThinShared};
 use rustc_codegen_ssa::back::write::CodegenContext;
 use rustc_codegen_ssa::{CodegenResults, NativeLib};
 use rustc_data_structures::fx::FxHashSet;
@@ -634,7 +634,7 @@ pub(crate) fn run_thin(
     cgcx: &CodegenContext<SpirvCodegenBackend>,
     modules: Vec<(String, SpirvModuleBuffer)>,
     cached_modules: Vec<(SerializedModule<SpirvModuleBuffer>, WorkProduct)>,
-) -> Result<(Vec<LtoModuleCodegen<SpirvCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> Result<(Vec<ThinModule<SpirvCodegenBackend>>, Vec<WorkProduct>), FatalError> {
     if cgcx.opts.cg.linker_plugin_lto.enabled() {
         unreachable!("We should never reach this case if the LTO step is deferred to the linker");
     }
@@ -668,10 +668,10 @@ pub(crate) fn run_thin(
 
     let mut opt_jobs = vec![];
     for (module_index, _) in shared.module_names.iter().enumerate() {
-        opt_jobs.push(LtoModuleCodegen::Thin(ThinModule {
+        opt_jobs.push(ThinModule {
             shared: shared.clone(),
             idx: module_index,
-        }));
+        });
     }
 
     Ok((opt_jobs, vec![]))

rust-toolchain.toml

@@ -1,7 +1,7 @@
 [toolchain]
-channel = "nightly-2025-07-14"
+channel = "nightly-2025-07-28"
 components = ["rust-src", "rustc-dev", "llvm-tools"]
-# commit_hash = e9182f195b8505c87c4bd055b9f6e114ccda0981
+# commit_hash = f8e355c230c6eb7b78ffce6a92fd81f78c890524
 
 # Whenever changing the nightly channel, update the commit hash above, and
 # change `REQUIRED_RUST_TOOLCHAIN` in `crates/rustc_codegen_spirv/build.rs` too.