cleaned up some tests

Additionally, remove unused `tests/ui/auxiliary/svh-*` crates that are duplicates of `tests/ui/svh/auxiliary/svh-*`.

Author: Kivooeo

tests/ui/auxiliary/svh-a-base.rs

@@ -1,5 +1,10 @@
+//! This test verifies that a direct non-primitive cast from an enum to an integer type
+//! is correctly disallowed, even when a `From` implementation exists for that enum.
+
 //@ run-rustfix
+
 #![allow(dead_code, unused_variables)]
+
 enum NonNullary {
     Nullary,
     Other(isize),
@@ -16,5 +21,7 @@ impl From<NonNullary> for isize {
 
 fn main() {
     let v = NonNullary::Nullary;
-    let val = isize::from(v); //~ ERROR non-primitive cast: `NonNullary` as `isize` [E0605]
+    let val = isize::from(v);
+    //~^ ERROR non-primitive cast: `NonNullary` as `isize` [E0605]
+    //~| HELP consider using the `From` trait instead
 }

tests/ui/auxiliary/svh-b.rs

@@ -1,5 +1,10 @@
+//! This test verifies that a direct non-primitive cast from an enum to an integer type
+//! is correctly disallowed, even when a `From` implementation exists for that enum.
+
 //@ run-rustfix
+
 #![allow(dead_code, unused_variables)]
+
 enum NonNullary {
     Nullary,
     Other(isize),
@@ -16,5 +21,7 @@ impl From<NonNullary> for isize {
 
 fn main() {
     let v = NonNullary::Nullary;
-    let val = v as isize; //~ ERROR non-primitive cast: `NonNullary` as `isize` [E0605]
+    let val = v as isize;
+    //~^ ERROR non-primitive cast: `NonNullary` as `isize` [E0605]
+    //~| HELP consider using the `From` trait instead
 }

tests/ui/cast/cast-enum-to-primitive-error.fixed

@@ -1,5 +1,5 @@
 error[E0605]: non-primitive cast: `NonNullary` as `isize`
-  --> $DIR/tag-variant-cast-non-nullary.rs:19:15
+  --> $DIR/cast-enum-to-primitive-error.rs:24:15
    |
 LL |     let val = v as isize;
    |               ^^^^^^^^^^ an `as` expression can be used to convert enum types to numeric types only if the enum type is unit-only or field-less

tests/ui/cast/cast-enum-to-primitive-error.rs

@@ -1,5 +1,7 @@
+//! This test checks that various forms of "trivial" casts and coercions
+//! can be explicitly performed using the `as` keyword without compilation errors.
+
 //@ run-pass
-// Test that all coercions can actually be done using casts (modulo the lints).
 
 #![allow(trivial_casts, trivial_numeric_casts)]
 

tests/ui/cast/cast-enum-to-primitive-error.stderr

@@ -1,5 +1,5 @@
 warning: method `foo` is never used
-  --> $DIR/trivial_casts-rpass.rs:7:8
+  --> $DIR/coercion-as-explicit-cast.rs:9:8
    |
 LL | trait Foo {
    |       --- method in this trait

tests/ui/cast/coercion-as-explicit-cast.rs

@@ -1,6 +1,15 @@
-enum Quux<T> { Bar }
-//~^ ERROR: parameter `T` is never used
+//! This test checks that unused generics are rejected by compiler
 
-fn foo(c: Quux) { assert!((false)); } //~ ERROR missing generics for enum `Quux`
+enum Quux<T> {
+    //~^ ERROR: parameter `T` is never used
+    Bar,
+}
 
-fn main() { panic!(); }
+fn foo(c: Quux) {
+    //~^ ERROR missing generics for enum `Quux`
+    assert!((false));
+}
+
+fn main() {
+    panic!();
+}

tests/ui/cast/coercion-as-explicit-cast.stderr

@@ -1,26 +1,26 @@
 error[E0392]: type parameter `T` is never used
-  --> $DIR/tag-type-args.rs:1:11
+  --> $DIR/generic-enum-errors.rs:3:11
    |
-LL | enum Quux<T> { Bar }
+LL | enum Quux<T> {
    |           ^ unused type parameter
    |
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
    = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead
 
 error[E0107]: missing generics for enum `Quux`
-  --> $DIR/tag-type-args.rs:4:11
+  --> $DIR/generic-enum-errors.rs:8:11
    |
-LL | fn foo(c: Quux) { assert!((false)); }
+LL | fn foo(c: Quux) {
    |           ^^^^ expected 1 generic argument
    |
 note: enum defined here, with 1 generic parameter: `T`
-  --> $DIR/tag-type-args.rs:1:6
+  --> $DIR/generic-enum-errors.rs:3:6
    |
-LL | enum Quux<T> { Bar }
+LL | enum Quux<T> {
    |      ^^^^ -
 help: add missing generic argument
    |
-LL | fn foo(c: Quux<T>) { assert!((false)); }
+LL | fn foo(c: Quux<T>) {
    |               +++
 
 error: aborting due to 2 previous errors

tests/ui/generics/generic-enum-errors.rs

@@ -1,3 +1,5 @@
+//! Check path resolution using `super`
+
 //@ run-pass
 
 #![allow(dead_code)]
@@ -6,10 +8,9 @@ pub mod a {
     pub fn f() {}
     pub mod b {
         fn g() {
-            super::f();
+            super::f(); // Accessing `f` from module `a` (parent of `b`)
         }
     }
 }
 
-pub fn main() {
-}
+pub fn main() {}