transpile, ast-exporter: fix compat with Clang 22

Clang 22 removes `ElaboratedType` and now represents `size_t`/`ssize_t`/`ptrdiff_t` using `PredefinedSugarType` (see llvm PR #143653).
Snapshots are now appended a tag w/ the earliest clang version they pass with; ie clang-22 still tests against `.clang15` snapshots if the
snapshot doesn't change between versions. Overriding a test to use a different `.clangX` tag can be done by appending the test to
a table in `snapshots.rs`.

Author: Crocodoctopus

.github/workflows/ci.yml

@@ -18,6 +18,10 @@ jobs:
             os: Linux
             arch: x86_64
             clang-version: 15
+          - runner: macos-15
+            os: macOS
+            arch: aarch64
+            clang-version: 22
           - runner: macos-15
             os: macOS
             arch: aarch64

README.md

@@ -118,7 +118,7 @@ LLVM_CONFIG_PATH="$(brew --prefix)/opt/llvm/bin/llvm-config" cargo install --loc
 or for a specific LLVM version,
 
 ```sh
-LLVM_CONFIG_PATH="$(brew --prefix)/opt/llvm@21/bin/llvm-config" cargo install --locked c2rust
+LLVM_CONFIG_PATH="$(brew --prefix)/opt/llvm@22/bin/llvm-config" cargo install --locked c2rust
 ```
 
 On Gentoo, you need to point the build system to

c2rust-ast-exporter/build.rs

@@ -217,6 +217,20 @@ fn build_native(llvm_info: &LLVMInfo) {
                 .unwrap();
             clang_libs.insert(sema_pos + 1, "clangAPINotes");
         }
+        if llvm_info.llvm_major_version >= 22 {
+            // clang 22+ moved option parsing helpers into a separate library.
+            // Keep this after users like clangFrontend/clangDriver.
+            let driver_pos = clang_libs.iter().position(|&r| r == "clangDriver").unwrap();
+            clang_libs.insert(driver_pos + 1, "clangOptions");
+
+            // clang 22+ split lifetime safety analysis from clangAnalysis.
+            // Keep this after users like clangSema.
+            let analysis_pos = clang_libs
+                .iter()
+                .position(|&r| r == "clangAnalysis")
+                .unwrap();
+            clang_libs.insert(analysis_pos + 1, "clangAnalysisLifetimeSafety");
+        }
 
         for lib in &clang_libs {
             println!("cargo:rustc-link-lib={}", lib);

c2rust-ast-exporter/src/AstExporter.cpp

@@ -657,6 +657,7 @@ class TypeEncoder final : public TypeVisitor<TypeEncoder> {
         VisitQualType(t);
     }
 
+#if CLANG_VERSION_MAJOR < 22
     void VisitElaboratedType(const ElaboratedType *T) {
         auto t = T->desugar();
         auto qt = encodeQualType(t);
@@ -665,6 +666,7 @@ class TypeEncoder final : public TypeVisitor<TypeEncoder> {
 
         VisitQualType(t);
     }
+#endif
 
     void VisitDecayedType(const DecayedType *T) {
         auto t = T->desugar();
@@ -690,6 +692,16 @@ class TypeEncoder final : public TypeVisitor<TypeEncoder> {
 
         VisitQualType(t);
     }
+
+#if CLANG_VERSION_MAJOR >= 22
+    void VisitPredefinedSugarType(const clang::PredefinedSugarType *T) {
+        auto t = T->desugar();
+        auto k = T->getKind();
+        encodeType(T, TagPredefinedSugarType,
+                   [k](CborEncoder *local) { cbor_encode_uint(local, uint64_t(k)); });
+        VisitQualType(t);
+    }
+#endif
 };
 
 class TranslateASTVisitor final
@@ -2267,8 +2279,6 @@ class TranslateASTVisitor final
         auto recordAlignment = 0;
         auto byteSize = 0;
 
-        auto t = D->getTypeForDecl();
-
         auto loc = D->getSourceRange();
         std::vector<void *> childIds;
         if (def) {
@@ -2348,8 +2358,6 @@ class TranslateASTVisitor final
         // They are used in actual code and accepted by compilers, so we cannot
         // exit early via code like `if (!D->isCompleteDefinition()) return true;`.
 
-        auto t = D->getTypeForDecl();
-
         std::vector<void *> childIds;
         for (auto x : D->enumerators()) {
             childIds.push_back(x->getCanonicalDecl());

c2rust-ast-exporter/src/ast_tags.hpp

@@ -154,6 +154,7 @@ enum TypeTag {
     TagAtomicType,
 
     TagAutoType,
+    TagPredefinedSugarType,
 };
 
 enum StringTypeTag {

c2rust-build-paths/src/lib.rs

@@ -91,6 +91,7 @@ pub fn find_llvm_config() -> Option<PathBuf> {
         .or_else(|| {
             // In PATH
             [
+                "llvm-config-22",
                 "llvm-config-21",
                 "llvm-config-20",
                 "llvm-config-19",
@@ -109,6 +110,7 @@ pub fn find_llvm_config() -> Option<PathBuf> {
                 "llvm-config-7.0",
                 "llvm-config",
                 // Homebrew install locations on Intel macOS
+                "/usr/local/opt/llvm@22/bin/llvm-config",
                 "/usr/local/opt/llvm@21/bin/llvm-config",
                 "/usr/local/opt/llvm@20/bin/llvm-config",
                 "/usr/local/opt/llvm@19/bin/llvm-config",
@@ -125,6 +127,7 @@ pub fn find_llvm_config() -> Option<PathBuf> {
                 "/usr/local/opt/llvm@8/bin/llvm-config",
                 "/usr/local/opt/llvm/bin/llvm-config",
                 // Homebrew install locations on Apple Silicon macOS
+                "/opt/homebrew/opt/llvm@22/bin/llvm-config",
                 "/opt/homebrew/opt/llvm@21/bin/llvm-config",
                 "/opt/homebrew/opt/llvm@20/bin/llvm-config",
                 "/opt/homebrew/opt/llvm@19/bin/llvm-config",

c2rust-transpile/src/c_ast/conversion.rs

@@ -813,6 +813,21 @@ impl ConversionContext {
                     self.processed_nodes.insert(new_id, expected_ty);
                 }
 
+                TypeTag::TagPredefinedSugarType => {
+                    let kind = from_value(ty_node.extras[0].clone())
+                        .expect("Predefined sugar type kind not found");
+
+                    // See `clang::PredefinedSugarKind`.
+                    let predef_sugar_ty = match kind {
+                        0 => CTypeKind::Size,
+                        1 => CTypeKind::SSize,
+                        2 => CTypeKind::PtrDiff,
+                        _ => panic!("Predefined sugar type kind {kind} not known"),
+                    };
+                    self.add_type(new_id, not_located(predef_sugar_ty));
+                    self.processed_nodes.insert(new_id, expected_ty);
+                }
+
                 TypeTag::TagEnumType if expected_ty & OTHER_TYPE != 0 => {
                     let decl = from_value(ty_node.extras[0].clone()).expect("Enum decl not found");
                     let decl_new = CDeclId(self.visit_node_type(decl, ENUM_DECL));

c2rust-transpile/tests/snapshots.rs

@@ -4,6 +4,7 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::process::Command;
 
+use c2rust_ast_exporter::get_clang_major_version;
 use c2rust_rust_tools::rustc;
 use c2rust_rust_tools::sanitize_file_name;
 use c2rust_rust_tools::RustEdition;
@@ -105,6 +106,26 @@ fn transpile_snapshot(
     expect_compile_error: bool,
     imported_crates: &[&str],
 ) {
+    let c_file_name = c_path.file_name().unwrap().to_str().unwrap();
+    let c_file_name = sanitize_file_name(&c_file_name);
+
+    // Some versions of clang can produce results different from their snapshots,
+    // those tests append the clang version to the snapshot of the failing test.
+    let clang_ver = match (get_clang_major_version().unwrap(), c_file_name.as_str()) {
+        // Tests that change @ clang-22
+        (22.., "varargs.c") => "clang22",
+        (22.., "wide_strings.c") => "clang22",
+        (22.., "auto_type.c") => "clang22",
+
+        // Tests that changed @ clang-17
+
+        // The minimum tested clang
+        (15.., _) => "clang15",
+
+        // Clang versions bellow 15 test against 15 and hope for the best
+        (0.., _) => "clang15",
+    };
+
     let cfg = config(edition);
     compile_and_transpile_file(c_path, cfg);
     let cwd = current_dir().unwrap();
@@ -116,9 +137,10 @@ fn transpile_snapshot(
     let rs_path = c_path.with_extension("rs");
     // We need to move the `.rs` file to a platform/edition-specific name
     // so that they don't overwrite each other.
-    let ext = [&[edition.as_str()][..], platform]
+    let ext = [&[edition.as_str()][..], platform, &[clang_ver][..]]
         .into_iter()
         .flatten()
+        .filter(|s| !s.is_empty())
         .join(".");
     let old_rs_path = rs_path;
     let rs_path = old_rs_path.with_extension(format!("{ext}.rs"));
@@ -130,8 +152,6 @@ fn transpile_snapshot(
     // Replace real paths with placeholders
     let rs = rs.replace(cwd.to_str().unwrap(), ".");
 
-    let c_file_name = c_path.file_name().unwrap().to_str().unwrap();
-    let c_file_name = sanitize_file_name(&c_file_name);
     let snapshot_name = format!("transpile@{c_file_name}.{ext}");
 
     insta::assert_snapshot!(snapshot_name, &rs, &debug_expr);

…/snapshots__transpile@alloca.c.2021.snap …ts__transpile@alloca.c.2021.clang15.snapc2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2021.snap renamed to c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2021.clang15.snap c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2021.snap renamed to c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2021.clang15.snap

@@ -1,6 +1,6 @@
 ---
 source: c2rust-transpile/tests/snapshots.rs
-expression: cat tests/snapshots/alloca.2021.rs
+expression: cat tests/snapshots/alloca.2021.clang15.rs
 ---
 #![allow(
     clippy::missing_safety_doc,

…/snapshots__transpile@alloca.c.2024.snap …ts__transpile@alloca.c.2024.clang15.snapc2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2024.snap renamed to c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2024.clang15.snap c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2024.snap renamed to c2rust-transpile/tests/snapshots/snapshots__transpile@alloca.c.2024.clang15.snap

@@ -1,6 +1,6 @@
 ---
 source: c2rust-transpile/tests/snapshots.rs
-expression: cat tests/snapshots/alloca.2024.rs
+expression: cat tests/snapshots/alloca.2024.clang15.rs
 ---
 #![allow(
     clippy::missing_safety_doc,