Rollup merge of #122644 - Nadrieril:complexity-tests, r=compiler-errors

pattern analysis: add a custom test harness

There are two features of the pattern analysis code that are hard to test: the newly-added pattern complexity limit, and the computation of arm intersections. This PR adds some crate-specific tests for that, including an unmaintainable but pretty macro to help construct patterns.

r? `````@compiler-errors`````

1 files changed, 4 insertions, 3 deletions

diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs
index 4cb306b1950..ae3eabe1745 100644
--- a/compiler/rustc_pattern_analysis/src/rustc.rs
+++ b/compiler/rustc_pattern_analysis/src/rustc.rs
@@ -880,13 +880,14 @@ impl<'p, 'tcx: 'p> PatCx for RustcPatCtxt<'p, 'tcx> {
 
     fn write_variant_name(
         f: &mut fmt::Formatter<'_>,
-        pat: &crate::pat::DeconstructedPat<Self>,
+        ctor: &crate::constructor::Constructor<Self>,
+        ty: &Self::Ty,
     ) -> fmt::Result {
-        if let ty::Adt(adt, _) = pat.ty().kind() {
+        if let ty::Adt(adt, _) = ty.kind() {
             if adt.is_box() {
                 write!(f, "Box")?
             } else {
-                let variant = adt.variant(Self::variant_index_for_adt(pat.ctor(), *adt));
+                let variant = adt.variant(Self::variant_index_for_adt(ctor, *adt));
                 write!(f, "{}", variant.name)?;
             }
         }