reorganize tests a bit

Author: RalfJung

tests/ui/consts/monomorphization/dead-code-in-called-fn.no-opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-called-fn.no-opt.stderr

@@ -13,6 +13,7 @@ impl<T> Fail<T> {
 fn called<T>() {
     // Any function that is called is guaranteed to have all consts that syntactically
     // appear in its body evaluated, even if they only appear in dead code.
+    // This relies on mono-item collection checking `required_consts` in collected functions.
     if false {
         let _ = Fail::<T>::C;
     }

tests/ui/consts/monomorphization/dead-code-in-called-fn.opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-called-fn.opt.stderr

@@ -7,7 +7,7 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: erroneous constant encountered
-  --> $DIR/dead-code-in-const-called-fn.rs:16:9
+  --> $DIR/dead-code-in-const-called-fn.rs:17:9
    |
 LL |         Fail::<T>::C;
    |         ^^^^^^^^^^^^

tests/ui/consts/monomorphization/dead-code-in-called-fn.rs renamed to tests/ui/consts/required-consts/dead-code-in-called-fn.rs

@@ -7,7 +7,7 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: erroneous constant encountered
-  --> $DIR/dead-code-in-const-called-fn.rs:16:9
+  --> $DIR/dead-code-in-const-called-fn.rs:17:9
    |
 LL |         Fail::<T>::C;
    |         ^^^^^^^^^^^^

tests/ui/consts/monomorphization/dead-code-in-const-called-fn.no-opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-const-called-fn.no-opt.stderr

@@ -13,6 +13,7 @@ const fn no_codegen<T>() {
     if false {
         // This bad constant is only used in dead code in a no-codegen function... and yet we still
         // must make sure that the build fails.
+        // This relies on const-eval evaluating all `required_consts` of `const fn`.
         Fail::<T>::C; //~ constant
     }
 }

tests/ui/consts/monomorphization/dead-code-in-const-called-fn.opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-const-called-fn.opt.stderr

@@ -11,9 +11,13 @@ impl<T> Fail<T> {
 
 // This function is not actually called, but it is mentioned in dead code in a function that is
 // called. Make sure we still find this error.
+// This relies on mono-item collection checking `required_consts` in functions that syntactically
+// are called in collected functions (even inside dead code).
 #[inline(never)]
 fn not_called<T>() {
-    let _ = Fail::<T>::C;
+    if false {
+        let _ = Fail::<T>::C;
+    }
 }
 
 #[inline(never)]

tests/ui/consts/monomorphization/dead-code-in-const-called-fn.rs renamed to tests/ui/consts/required-consts/dead-code-in-const-called-fn.rs

@@ -7,9 +7,9 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: the above error was encountered while instantiating `fn <std::vec::Vec<i32> as MyTrait>::not_called`
-  --> $DIR/dead-code-in-dead-vtable.rs:28:40
+  --> $DIR/dead-code-in-dead-vtable.rs:30:40
    |
-LL |         let gen_vtable: &dyn MyTrait = &v;
+LL |         let gen_vtable: &dyn MyTrait = &v; // vtable "appears" here
    |                                        ^^
 
 error: aborting due to 1 previous error

tests/ui/consts/monomorphization/dead-code-in-dead-drop.no-opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-dead-drop.no-opt.stderr

@@ -15,17 +15,21 @@ trait MyTrait {
 
 // This function is not actually called, but it is mentioned in a vtable in a function that is
 // called. Make sure we still find this error.
+// This relies on mono-item collection checking `required_consts` in functions that are referenced
+// in vtables that syntactically appear in collected functions (even inside dead code).
 impl<T> MyTrait for Vec<T> {
     fn not_called(&self) {
-        let _ = Fail::<T>::C;
+        if false {
+            let _ = Fail::<T>::C;
+        }
     }
 }
 
 #[inline(never)]
 fn called<T>() {
     if false {
         let v: Vec<T> = Vec::new();
-        let gen_vtable: &dyn MyTrait = &v;
+        let gen_vtable: &dyn MyTrait = &v; // vtable "appears" here
     }
 }
 

tests/ui/consts/monomorphization/dead-code-in-dead-drop.opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-dead-drop.opt.stderr

@@ -7,7 +7,7 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: erroneous constant encountered
-  --> $DIR/dead-code-in-static.rs:15:9
+  --> $DIR/dead-code-in-static.rs:16:9
    |
 LL |         Fail::<i32>::C;
    |         ^^^^^^^^^^^^^^

tests/ui/consts/monomorphization/dead-code-in-dead-drop.rs renamed to tests/ui/consts/required-consts/dead-code-in-dead-drop.rs

@@ -7,7 +7,7 @@ LL |     const C: () = panic!();
    = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: erroneous constant encountered
-  --> $DIR/dead-code-in-static.rs:15:9
+  --> $DIR/dead-code-in-static.rs:16:9
    |
 LL |         Fail::<i32>::C;
    |         ^^^^^^^^^^^^^^

tests/ui/consts/monomorphization/dead-code-in-dead-fn.no-opt.stderr renamed to tests/ui/consts/required-consts/dead-code-in-dead-fn.no-opt.stderr

@@ -12,6 +12,7 @@ pub static FOO: () = {
     if false {
         // This bad constant is only used in dead code in a static initializer... and yet we still
         // must make sure that the build fails.
+        // This relies on const-eval evaluating all `required_consts` of the `static` MIR body.
         Fail::<i32>::C; //~ constant
     }
 };