sem/eval: fix TestCastMap properly for AnyTuple

`TestCastMap` iterates over `types.OidToType` map to find all
interesting pairs to perform the cast between. One of the representative
types in the map is `types.AnyTuple` that is actually not a valid
execution-time type (it's a wildcard used only during static analysis).
Previously we could crash in the test if we happen to pick a float value
as the element corresponding to the single Any type element (because
float width is 0 there). This commit fixes the test by effectively
"resolving" `AnyTuple` type to a concrete tuple type with a single
random type as the element.

Release note: None

Author: yuzefovich

pkg/sql/sem/eval/cast_map_test.go

@@ -38,6 +38,21 @@ func TestCastMap(t *testing.T) {
 
 	cast.ForEachCast(func(src, tgt oid.Oid, _ cast.Context, _ cast.ContextOrigin, _ volatility.V) {
 		srcType := types.OidToType[src]
+		if srcType.Oid() == oid.T_record {
+			// We're looking at the types.AnyTuple that is a wildcard that
+			// cannot be used during execution. In order to make it a valid
+			// execution type, we construct an equivalent with the tuple element
+			// resolved to a random type.
+			var emptyLocale = ""
+			srcType = &types.T{
+				InternalType: types.InternalType{
+					Family:        types.TupleFamily,
+					TupleContents: []*types.T{randgen.RandType(rng)},
+					Oid:           oid.T_record,
+					Locale:        &emptyLocale,
+				},
+			}
+		}
 		tgtType := types.OidToType[tgt]
 		srcDatum := randgen.RandDatum(rng, srcType, false /* nullOk */)