Refactor C++ overload tests to support multiple C++ classes

.github/workflows/check.yml

@@ -124,6 +124,7 @@ jobs:
         # and disable color output.
         # FIXME: turn this into a script so we can run it locally.
         run: |
+            cargo fmt --package splat-overload-diagnostics -- --check
             export CARGO_TERM_COLOR=never
             set -o pipefail
             TEST_NAMES=$(find splat-overload-diagnostics/src/bin -name "*.rs" | \
@@ -148,7 +149,7 @@ jobs:
             done
 
   cpp-overload-test-ok:
-    name: 9. Check Ok C++ overloads
+    name: 9. Check C++ overloads
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -157,17 +158,14 @@ jobs:
           toolchain: nightly
           # Use the same components in every step for caching
           components: cargo,clippy,rustfmt
+      # FIXME: turn this into a script so contributors can run it locally.
       - name: Check C++ overload ok cases
-        # FIXME: turn this into a script so contributors can run it locally.
         run: |
-            set -o pipefail
-            TEST_NAMES=$(find cpp-overload-test/src/bin -name "*-ok.rs" | \
-                sed 's|.*/\([^/]*\).rs|\1|g' )
-            echo "testing ok: $TEST_NAMES"
-            for test_name in $TEST_NAMES; do
-                echo "testing ok: $test_name"
-                cargo build --all-features --package cpp-overload-test --bin "$test_name"
-            done
+            cargo build --all-features --package cpp-overload-test --lib
+            cargo clippy --all-features --package cpp-overload-test -- --deny warnings
+            cargo test --all-features --package cpp-overload-test --lib
+            cargo test --doc --all-features --package cpp-overload-test
+            cargo fmt --package cpp-overload-test -- --check
 
   cpp-overload-test-fail:
     name: 10. Must-fail C++ overloads
@@ -180,21 +178,21 @@ jobs:
           # Use the same components in every step for caching
           components: cargo,clippy,rustfmt
       - name: Check C++ overload fail cases
-        # To bless (update the expected output), change '/tmp' to 'cpp-overload-test/src/bin',
+        # To bless (update the expected output), change '/tmp' to 'cpp-overload-test/examples',
         # and disable color output.
         # FIXME: turn this into a script so contributors can run it locally.
         run: |
             export CARGO_TERM_COLOR=never
             set -o pipefail
-            TEST_NAMES=$(find cpp-overload-test/src/bin -name "*-fail.rs" | \
+            TEST_NAMES=$(find cpp-overload-test/examples -name "*.rs" | \
                 sed 's|.*/\([^/]*\).rs|\1|g' )
             echo "testing incompatible overloads: $TEST_NAMES"
             for test_name in $TEST_NAMES; do
                 echo "testing incompatible overloads: $test_name"
                 # We expect cargo to fail, so don't exit the shell when it does
                 set +e
                 # Ignore build progress, if it's cached then the built crates change
-                cargo build --all-features --package cpp-overload-test --bin "$test_name" 2>&1 | \
+                cargo build --all-features --package cpp-overload-test --example "$test_name" 2>&1 | \
                     grep --invert-match -e 'Updating .* index' -e 'Downloading .*' -e 'Downloaded .*' -e 'Compiling [^ ]* .*' \
                     > "/tmp/$test_name.stderr"
                 CARGO_EXIT_CODE=$?
@@ -204,31 +202,9 @@ jobs:
                     exit 1
                 fi
                 echo "comparing incompatible overload diagnostics for: $test_name"
-                diff --unified=5 "cpp-overload-test/src/bin/$test_name.stderr" /tmp/"$test_name.stderr"
+                diff --unified=5 "cpp-overload-test/examples/$test_name.stderr" /tmp/"$test_name.stderr"
             done
 
-  cpp-overload-file-names:
-    name: 11. Incorrect C++ overload file names
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-      - uses: actions-rust-lang/setup-rust-toolchain@166cdcfd11aee3cb47222f9ddb555ce30ddb9659 # v1.17.0
-        with:
-          toolchain: nightly
-          # Use the same components in every step for caching
-          components: cargo,clippy,rustfmt
-      - name: Check C++ overload file names
-        # FIXME: turn this into a script so contributors can run it locally.
-        run: |
-            set -o pipefail
-            TEST_NAMES=$(find cpp-overload-test/src/bin -name "*.rs" -not -name "*-ok.rs" -not -name "*-fail.rs" | \
-                sed 's|.*/\([^/]*\).rs|\1|g' )
-            echo "incorrect file names: $TEST_NAMES"
-            if [[ -n "$TEST_NAMES" ]]; then
-                echo "error: incorrect file names found: all Rust files must be named *-ok.rs or *-fail.rs"
-                exit 1
-            fi
-
   all:
     name: All checks
     # Always run this job, even if earlier steps were skipped (or failed):
@@ -246,7 +222,6 @@ jobs:
       - diagnostics-rust
       - cpp-overload-test-ok
       - cpp-overload-test-fail
-      - cpp-overload-file-names
     steps:
       - name: Fail if any other job failed
         # Every job status needs to be checked here, because `always()` stops failures from propagating automatically
@@ -262,4 +237,3 @@ jobs:
           [[ "${{ needs.diagnostics-rust.result }}" == "success" ]] || exit 1
           [[ "${{ needs.cpp-overload-test-ok.result }}" == "success" ]] || exit 1
           [[ "${{ needs.cpp-overload-test-fail.result }}" == "success" ]] || exit 1
-          [[ "${{ needs.cpp-overload-file-names.result }}" == "success" ]] || exit 1

cpp-overload-test/build.rs

@@ -1,6 +1,5 @@
 fn main() {
-    cpp_build::build("src/bin/std-forward-list-ok.rs");
-    // FIXME: move these into the crate root instead of examples, `cpp_build` doesn't work with
-    // multiple examples.
-    //cpp_build::build("src/bin/std-forward-list-fail.rs");
+    // `cpp_build` doesn't work with multiple example/binary builds in the same crate, so we use
+    // lib.rs submodules for successful overloads.
+    cpp_build::build("src/lib.rs");
 }

cpp-overload-test/examples/stdcpp-forward-list.rs

@@ -0,0 +1,9 @@
+//! Test C++ overloads that can't be represented in Rust, and record the macro diagnostics.
+//!
+//! The `cpp!` macro doesn't work here, because of technical limitations it can only run one build
+//! per crate. (Examples and binaries are built separately from `lib.rs`.)
+//! To add C++ code here, use /* ... */ code comment blocks.
+
+fn main() {
+    const _: () = panic!("There are no failing overloads for C++ `std::forward_list` yet");
+}

cpp-overload-test/src/bin/std-forward-list-fail.stderr → cpp-overload-test/examples/stdcpp-forward-list.stderr

@@ -1,8 +1,8 @@
 error[E0080]: evaluation panicked: There are no failing overloads for C++ `std::forward_list` yet
- --> cpp-overload-test/src/bin/std-forward-list-fail.rs:2:19
+ --> cpp-overload-test/examples/stdcpp-forward-list.rs:8:19
   |
-2 |     const _: () = panic!("There are no failing overloads for C++ `std::forward_list` yet");
+8 |     const _: () = panic!("There are no failing overloads for C++ `std::forward_list` yet");
   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `main::_` failed here
 
 For more information about this error, try `rustc --explain E0080`.
-error: could not compile `cpp-overload-test` (bin "std-forward-list-fail") due to 1 previous error
+error: could not compile `cpp-overload-test` (example "stdcpp-forward-list") due to 1 previous error

cpp-overload-test/src/lib.rs

@@ -0,0 +1,11 @@
+//! Test C++ overloads that can be successfully represented in Rust.
+//! Each type in the C++ standard library has a module under `stdcpp`.
+
+#![feature(splat, tuple_trait)]
+#![allow(incomplete_features)]
+
+/// The C++ standard library.
+pub mod stdcpp {
+    // Add new modules for each type here, in alphabetical order.
+    pub mod forward_list;
+}

cpp-overload-test/src/bin/std-forward-list-ok.rs → cpp-overload-test/src/stdcpp/forward_list.rs

@@ -1,5 +1,4 @@
-#![feature(splat, tuple_trait)]
-#![allow(incomplete_features)]
+//! Test that C++ overloads for `std::forward_list` can be successfully represented in Rust.
 #![allow(unused_braces)]
 
 use cpp::cpp;
@@ -105,7 +104,7 @@ overload! {
     }
 }
 
-fn main() {
+pub fn test_forward_list() {
     let mut default_list = StdForwardList::new();
     let _with_capacity = StdForwardList::new(10);
     let _repeat_with = StdForwardList::new(42, 100);