Rollup merge of #105793 - lukas-code:circular-deps, r=Mark-Simulacrum

Add note for mismatched types because of circular dependencies

If you have crate A with a dependency on crate B, and crate B with a dev-dependency on A, then you might see "mismatched types" errors on types that seem to be equal. This PR adds a note that explains that the types are different, because crate B is compiled twice, one time with `cfg(test)` and one time without.

I haven't found a good way to create circular dependencies in UI tests, so I abused the incremental tests instead. As a bonus, incremental tests support "cpass" now.

related to https://github.com/rust-lang/rust/issues/22750

2 files changed, 47 insertions, 0 deletions

diff --git a/tests/incremental/auxiliary/circular-dependencies-aux.rs b/tests/incremental/auxiliary/circular-dependencies-aux.rs
new file mode 100644
index 00000000000..0e74eb1b2f2
--- /dev/null
+++ b/tests/incremental/auxiliary/circular-dependencies-aux.rs
@@ -0,0 +1,10 @@
+// edition: 2021
+// compile-flags: --crate-type lib --extern circular_dependencies={{build-base}}/circular-dependencies/libcircular_dependencies.rmeta --emit dep-info,metadata
+
+use circular_dependencies::Foo;
+
+pub fn consume_foo(_: Foo) {}
+
+pub fn produce_foo() -> Foo {
+    Foo
+}
diff --git a/tests/incremental/circular-dependencies.rs b/tests/incremental/circular-dependencies.rs
new file mode 100644
index 00000000000..10673066a9d
--- /dev/null
+++ b/tests/incremental/circular-dependencies.rs
@@ -0,0 +1,37 @@
+// ignore-tidy-linelength
+// revisions: cpass1 cfail2
+// edition: 2021
+// [cpass1] compile-flags: --crate-type lib --emit dep-info,metadata
+// [cfail2] aux-build: circular-dependencies-aux.rs
+// [cfail2] compile-flags: --test --extern aux={{build-base}}/circular-dependencies/auxiliary/libcircular_dependencies_aux.rmeta -L dependency={{build-base}}/circular-dependencies
+
+pub struct Foo;
+//[cfail2]~^ NOTE `Foo` is defined in the current crate
+//[cfail2]~| NOTE `Foo` is defined in the current crate
+//[cfail2]~| NOTE `circular_dependencies::Foo` is defined in crate `circular_dependencies`
+//[cfail2]~| NOTE `circular_dependencies::Foo` is defined in crate `circular_dependencies`
+
+pub fn consume_foo(_: Foo) {}
+//[cfail2]~^ NOTE function defined here
+
+pub fn produce_foo() -> Foo {
+    Foo
+}
+
+#[test]
+fn test() {
+    aux::consume_foo(produce_foo());
+    //[cfail2]~^ ERROR mismatched types [E0308]
+    //[cfail2]~| NOTE expected `circular_dependencies::Foo`, found `Foo`
+    //[cfail2]~| NOTE arguments to this function are incorrect
+    //[cfail2]~| NOTE `Foo` and `circular_dependencies::Foo` have similar names, but are actually distinct types
+    //[cfail2]~| NOTE the crate `circular_dependencies` is compiled multiple times, possibly with different configurations
+    //[cfail2]~| NOTE function defined here
+
+    consume_foo(aux::produce_foo());
+    //[cfail2]~^ ERROR mismatched types [E0308]
+    //[cfail2]~| NOTE expected `Foo`, found `circular_dependencies::Foo`
+    //[cfail2]~| NOTE arguments to this function are incorrect
+    //[cfail2]~| NOTE `circular_dependencies::Foo` and `Foo` have similar names, but are actually distinct types
+    //[cfail2]~| NOTE the crate `circular_dependencies` is compiled multiple times, possibly with different configurations
+}