Add inverted (var on left side) subtype tests

Expanding on our earlier bugfix, we've added additional tests where the
generalized inference var is on the left side. This will help catch any
bugs where the variance or the parameters inadvertantly get flipped.

Co-authored-by: David Ross <daboross@daboross.net>

Author: 2 people

tests/test/subtype.rs

@@ -224,6 +224,20 @@ fn multi_lifetime_covariant_struct() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 }  \
             ]}"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(Foo<U>, Foo<&'a u32>),
+                    Subtype(Foo<U>, Foo<&'b u32>)
+                }
+            }
+        } yields {
+            // Result should be identical to multi_lifetime result.
+            "Unique; for<?U1> { substitution [?0 := (&'^0.0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0  }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1  }  \
+            ]}"
+        }
     }
 }
 
@@ -250,6 +264,20 @@ fn multi_lifetime_contravariant_struct() {
                 InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 }  \
             ]}"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(Foo<U>, Foo<&'a u32>),
+                    Subtype(Foo<U>, Foo<&'b u32>)
+                }
+            }
+        } yields {
+            // Result should be opposite multi_lifetime result.
+            "Unique; for<?U1> { substitution [?0 := (&'^0.0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '!1_0: '^0.0 }, \
+                InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 }  \
+            ]}"
+        }
     }
 }
 
@@ -282,6 +310,27 @@ fn multi_lifetime_invariant_struct() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '!1_0 }  \
             ]"
         }
+
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(Foo<U>, Foo<&'a u32>),
+                    Subtype(Foo<U>, Foo<&'b u32>)
+                }
+            }
+        } yields[SolverChoice::recursive()] {
+            // Because A is invariant, we require the lifetimes to be equal
+            "Unique; substitution [?0 := (&'!1_0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '!1_0: '!1_1 }, \
+                InEnvironment { environment: Env([]), goal: '!1_1: '!1_0 }  \
+            ]"
+        } yields[SolverChoice::slg_default()] {
+            // Because A is invariant, we require the lifetimes to be equal
+            "Unique; substitution [?0 := (&'!1_1 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '!1_0: '!1_1 }, \
+                InEnvironment { environment: Env([]), goal: '!1_1: '!1_0 }  \
+            ]"
+        }
     }
 }
 
@@ -306,6 +355,20 @@ fn multi_lifetime_slice() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 } \
             ]}"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype([U], [&'a u32]),
+                    Subtype([U], [&'b u32])
+                }
+            }
+        } yields {
+            // Result should be identical to multi_lifetime result.
+            "Unique; for<?U1> { substitution [?0 := (&'^0.0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 } \
+            ]}"
+        }
     }
 }
 
@@ -330,6 +393,20 @@ fn multi_lifetime_tuple() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 } \
             ]}"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype((U,), (&'a u32,)),
+                    Subtype((U,), (&'b u32,))
+                }
+            }
+        } yields {
+            // Result should be identical to multi_lifetime result.
+            "Unique; for<?U1> { substitution [?0 := (&'^0.0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 } \
+            ]}"
+        }
     }
 }
 
@@ -354,6 +431,20 @@ fn multi_lifetime_array() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 } \
             ]}"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype([U; 16], [&'a u32; 16]),
+                    Subtype([U; 16], [&'b u32; 16])
+                }
+            }
+        } yields {
+            // Result should be identical to multi_lifetime result.
+            "Unique; for<?U1> { substitution [?0 := (&'^0.0 Uint(U32))], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 } \
+            ]}"
+        }
     }
 }
 
@@ -460,6 +551,20 @@ fn generalize_slice() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 }  \
             ] }"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(U, [&'a u32]),
+                    Subtype(U, [&'b u32])
+                }
+            }
+        } yields {
+            // Result should be identical to generalize_covariant_struct result.
+            "Unique; for<?U1> { substitution [?0 := [(&'^0.0 Uint(U32))]], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 }  \
+            ] }"
+        }
     }
 }
 
@@ -484,6 +589,20 @@ fn generalize_tuple() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 }  \
             ] }"
         }
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(U, (&'a u32,)),
+                    Subtype(U, (&'b u32,))
+                }
+            }
+        } yields {
+            // Result should be identical to generalize_covariant_struct result.
+            "Unique; for<?U1> { substitution [?0 := 1<(&'^0.0 Uint(U32))>], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 }  \
+            ] }"
+        }
     }
 }
 
@@ -509,6 +628,21 @@ fn generalize_2tuple() {
                 InEnvironment { environment: Env([]), goal: '!1_3: '^0.1 }  \
             ] }"
         }
+        goal {
+            forall<'a, 'b, 'c, 'd> {
+                exists<U> {
+                    Subtype(U, (&'a u32, &'c u32)),
+                    Subtype(U, (&'b u32, &'d u32))
+                }
+            }
+        } yields {
+            "Unique; for<?U1, ?U1> { substitution [?0 := 2<(&'^0.0 Uint(U32)), (&'^0.1 Uint(U32))>], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 }, \
+                InEnvironment { environment: Env([]), goal: '^0.1: '!1_2 }, \
+                InEnvironment { environment: Env([]), goal: '^0.1: '!1_3 }  \
+            ] }"
+        }
     }
 }
 
@@ -533,5 +667,20 @@ fn generalize_array() {
                 InEnvironment { environment: Env([]), goal: '!1_1: '^0.0 }  \
             ] }"
         }
+
+        goal {
+            forall<'a, 'b> {
+                exists<U> {
+                    Subtype(U, [&'a u32; 16]),
+                    Subtype(U, [&'b u32; 16])
+                }
+            }
+        } yields {
+            // Result should be identical to generalize_covariant_struct result.
+            "Unique; for<?U1> { substitution [?0 := [(&'^0.0 Uint(U32)); 16]], lifetime constraints [\
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_0 }, \
+                InEnvironment { environment: Env([]), goal: '^0.0: '!1_1 }  \
+            ] }"
+        }
     }
 }