Upgrade toolchain to 2025-04-01 (#3973)

Culprit PRs:
- rust-lang/rust#138384
- rust-lang/rust#127173
- rust-lang/rust#138659,

Resolves #3961, #3976

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

Author: carolynzech

kani-compiler/src/codegen_cprover_gotoc/codegen/foreign_function.rs

@@ -49,25 +49,35 @@ impl GotocCtx<'_> {
     /// handled later.
     pub fn codegen_foreign_fn(&mut self, instance: Instance) -> &Symbol {
         debug!(?instance, "codegen_foreign_function");
-        let fn_name = instance.mangled_name().intern();
+        let trimmed_fn_name = instance.trimmed_name().intern();
+        let mangled_fn_name = instance.mangled_name().intern();
         let loc = self.codegen_span_stable(instance.def.span());
-        if self.symbol_table.contains(fn_name) {
-            // Symbol has been added (either a built-in CBMC function or a Rust allocation function).
-            self.symbol_table.lookup(fn_name).unwrap()
-        } else if RUST_ALLOC_FNS.contains(&fn_name)
-            || (self.is_cffi_enabled() && instance.fn_abi().unwrap().conv == CallConvention::C)
-        {
+        if self.symbol_table.contains(mangled_fn_name) {
+            // Symbol has been added (a built-in CBMC function)
+            self.symbol_table.lookup(mangled_fn_name).unwrap()
+        } else if self.symbol_table.contains(trimmed_fn_name) {
+            // Symbol has been added (a Rust allocation function)
+            self.symbol_table.lookup(trimmed_fn_name).unwrap()
+        } else if RUST_ALLOC_FNS.contains(&trimmed_fn_name) {
             // Add a Rust alloc lib function as is declared by core.
+            // We use the trimmed name to ensure that it matches the function names in kani_lib.c
+            self.ensure(trimmed_fn_name, |gcx, _| {
+                let typ = gcx.codegen_ffi_type(instance);
+                Symbol::function(trimmed_fn_name, typ, None, instance.name(), loc)
+                    .with_is_extern(true)
+            })
+        } else if self.is_cffi_enabled() && instance.fn_abi().unwrap().conv == CallConvention::C {
             // When C-FFI feature is enabled, we just trust the rust declaration.
             // TODO: Add proper casting and clashing definitions check.
             // https://github.com/model-checking/kani/issues/1350
             // https://github.com/model-checking/kani/issues/2426
-            self.ensure(fn_name, |gcx, _| {
+            self.ensure(mangled_fn_name, |gcx, _| {
                 let typ = gcx.codegen_ffi_type(instance);
-                Symbol::function(fn_name, typ, None, instance.name(), loc).with_is_extern(true)
+                Symbol::function(mangled_fn_name, typ, None, instance.name(), loc)
+                    .with_is_extern(true)
             })
         } else {
-            let shim_name = format!("{fn_name}_ffi_shim");
+            let shim_name = format!("{mangled_fn_name}_ffi_shim");
             trace!(?shim_name, "codegen_foreign_function");
             self.ensure(&shim_name, |gcx, _| {
                 // Generate a shim with an unsupported C-FFI error message.

kani-compiler/src/codegen_cprover_gotoc/codegen/function.rs

@@ -266,11 +266,11 @@ pub mod rustc_smir {
             for mapping in &cov_info.mappings {
                 let Code { bcb } = mapping.kind else { unreachable!() };
                 let source_map = tcx.sess.source_map();
-                let file = source_map.lookup_source_file(cov_info.body_span.lo());
+                let file = source_map.lookup_source_file(mapping.span.lo());
                 if bcb == coverage {
                     return Some((
-                        make_source_region(source_map, cov_info, &file, mapping.span).unwrap(),
-                        rustc_internal::stable(cov_info.body_span).get_filename(),
+                        make_source_region(source_map, &file, mapping.span).unwrap(),
+                        rustc_internal::stable(mapping.span).get_filename(),
                     ));
                 }
             }

kani-compiler/src/codegen_cprover_gotoc/codegen/source_region.rs

@@ -5,7 +5,6 @@
 //! the `Span` to `CoverageRegion` conversion defined in
 //! https://github.com/rust-lang/rust/tree/master/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen/spans.rs
 
-use rustc_middle::mir::coverage::FunctionCoverageInfo;
 use rustc_span::Span;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{BytePos, SourceFile};
@@ -27,33 +26,22 @@ impl Debug for SourceRegion {
     }
 }
 
-fn ensure_non_empty_span(
-    source_map: &SourceMap,
-    fn_cov_info: &FunctionCoverageInfo,
-    span: Span,
-) -> Option<Span> {
+fn ensure_non_empty_span(source_map: &SourceMap, span: Span) -> Option<Span> {
     if !span.is_empty() {
         return Some(span);
     }
-    let lo = span.lo();
-    let hi = span.hi();
-    // The span is empty, so try to expand it to cover an adjacent '{' or '}',
-    // but only within the bounds of the body span.
-    let try_next = hi < fn_cov_info.body_span.hi();
-    let try_prev = fn_cov_info.body_span.lo() < lo;
-    if !(try_next || try_prev) {
-        return None;
-    }
+
+    // The span is empty, so try to enlarge it to cover an adjacent '{' or '}'.
     source_map
         .span_to_source(span, |src, start, end| try {
             // Adjusting span endpoints by `BytePos(1)` is normally a bug,
             // but in this case we have specifically checked that the character
             // we're skipping over is one of two specific ASCII characters, so
             // adjusting by exactly 1 byte is correct.
-            if try_next && src.as_bytes()[end] == b'{' {
-                Some(span.with_hi(hi + BytePos(1)))
-            } else if try_prev && src.as_bytes()[start - 1] == b'}' {
-                Some(span.with_lo(lo - BytePos(1)))
+            if src.as_bytes().get(end).copied() == Some(b'{') {
+                Some(span.with_hi(span.hi() + BytePos(1)))
+            } else if start > 0 && src.as_bytes()[start - 1] == b'}' {
+                Some(span.with_lo(span.lo() - BytePos(1)))
             } else {
                 None
             }
@@ -104,11 +92,10 @@ fn check_source_region(source_region: SourceRegion) -> Option<SourceRegion> {
 /// better than an ICE or `llvm-cov` failure that the user might have no way to avoid.
 pub(crate) fn make_source_region(
     source_map: &SourceMap,
-    fn_cov_info: &FunctionCoverageInfo,
     file: &SourceFile,
     span: Span,
 ) -> Option<SourceRegion> {
-    let span = ensure_non_empty_span(source_map, fn_cov_info, span)?;
+    let span = ensure_non_empty_span(source_map, span)?;
     let lo = span.lo();
     let hi = span.hi();
     // Column numbers need to be in bytes, so we can't use the more convenient

kani-compiler/src/kani_middle/resolve.rs

@@ -432,10 +432,10 @@ fn resolve_relative(tcx: TyCtxt, current_module: LocalModDefId, name: &str) -> R
     let mut glob_imports = vec![];
     let result = tcx.hir_module_free_items(current_module).find_map(|item_id| {
         let item = tcx.hir_item(item_id);
-        if item.ident.as_str() == name {
+        if item.kind.ident().is_some_and(|ident| ident.as_str() == name) {
             match item.kind {
-                ItemKind::Use(use_path, UseKind::Single) => use_path.res[0].opt_def_id(),
-                ItemKind::ExternCrate(orig_name) => resolve_external(
+                ItemKind::Use(use_path, UseKind::Single(_)) => use_path.res[0].opt_def_id(),
+                ItemKind::ExternCrate(orig_name, _) => resolve_external(
                     tcx,
                     orig_name.as_ref().map(|sym| sym.as_str()).unwrap_or(name),
                 ),

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2025-03-18"
+channel = "nightly-2025-04-01"
 components = ["llvm-tools", "rustc-dev", "rust-src", "rustfmt"]