Issue 22450: Address desugaring-box problems in [pretty] run-pass test suite.

Precursor for overloaded-`box` and placement-`in`; see Issue 22181.

Author: pnkfelix

src/test/run-pass/alignment-gep-tup-like-1.rs

@@ -31,10 +31,11 @@ impl<A:Clone> Invokable<A> for Invoker<A> {
 }
 
 fn f<A:Clone + 'static>(a: A, b: u16) -> Box<Invokable<A>+'static> {
-    box Invoker {
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box Invoker {
         a: a,
         b: b,
-    } as (Box<Invokable<A>+'static>)
+    }) as (Box<Invokable<A>+'static>)
 }
 
 pub fn main() {

src/test/run-pass/close-over-big-then-small-data.rs

@@ -35,10 +35,11 @@ impl<A:Clone> Invokable<A> for Invoker<A> {
 }
 
 fn f<A:Clone + 'static>(a: A, b: u16) -> Box<Invokable<A>+'static> {
-    box Invoker {
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box Invoker {
         a: a,
         b: b,
-    } as (Box<Invokable<A>+'static>)
+    }) as (Box<Invokable<A>+'static>)
 }
 
 pub fn main() {

src/test/run-pass/issue-2734.rs

@@ -17,7 +17,8 @@ trait hax {
 impl<A> hax for A { }
 
 fn perform_hax<T: 'static>(x: Box<T>) -> Box<hax+'static> {
-    box x as Box<hax+'static>
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box x) as Box<hax+'static>
 }
 
 fn deadcode() {

src/test/run-pass/issue-2735.rs

@@ -17,7 +17,8 @@ trait hax {
 impl<A> hax for A { }
 
 fn perform_hax<T: 'static>(x: Box<T>) -> Box<hax+'static> {
-    box x as Box<hax+'static>
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box x) as Box<hax+'static>
 }
 
 fn deadcode() {

src/test/run-pass/issue-7673-cast-generically-implemented-trait.rs

@@ -26,4 +26,5 @@ trait A {
 impl<T: 'static> A for T {}
 
 fn owned2<T: 'static>(a: Box<T>) { a as Box<A>; }
-fn owned3<T: 'static>(a: Box<T>) { box a as Box<A>; }
+// FIXME(22450): workaround pretty-printer deficiency via parens.
+fn owned3<T: 'static>(a: Box<T>) { (box a) as Box<A>; }

src/test/run-pass/kindck-owned-trait-contains-1.rs

@@ -20,7 +20,8 @@ impl<A:Clone + 'static> repeat<A> for Box<A> {
 }
 
 fn repeater<A:Clone + 'static>(v: Box<A>) -> Box<repeat<A>+'static> {
-    box v as Box<repeat<A>+'static> // No
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box v) as Box<repeat<A>+'static> // No
 }
 
 pub fn main() {

src/test/run-pass/regions-close-over-type-parameter-successfully.rs

@@ -23,7 +23,8 @@ impl<'a> SomeTrait for &'a int {
 }
 
 fn make_object<'a,A:SomeTrait+'a>(v: A) -> Box<SomeTrait+'a> {
-    box v as Box<SomeTrait+'a>
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    (box v) as Box<SomeTrait+'a>
 }
 
 fn main() {

src/test/run-pass/regions-early-bound-trait-param.rs

@@ -81,7 +81,8 @@ impl<'s> Trait<'s> for (int,int) {
 }
 
 impl<'t> MakerTrait for Box<Trait<'t>+'static> {
-    fn mk() -> Box<Trait<'t>+'static> { box() (4,5) as Box<Trait> }
+    // FIXME(22450): workaround pretty-printer deficiency via parens.
+    fn mk() -> Box<Trait<'t>+'static> { (box() (4,5)) as Box<Trait> }
 }
 
 enum List<'l> {