Extend const-loop and const-if to handle more cases

This makes sure that our HIR visitor is visiting as many
const-items as possible.

Author: ecstatic-morse

src/test/ui/consts/const-if.rs

@@ -1,5 +1,21 @@
-const _X: i32 = if true { 5 } else { 6 };
-//~^ ERROR constant contains unimplemented expression type
-//~| ERROR constant contains unimplemented expression type
+const _: i32 = if true { //~ ERROR if expression is not allowed in a const
+    5
+} else {
+    6
+};
+
+const _: i32 = match 1 { //~ ERROR match expression is not allowed in a const
+    2 => 3,
+    4 => 5,
+    _ => 0,
+};
+
+const fn foo() -> i32 {
+    if true { 5 } else { 6 } //~ ERROR if expression is not allowed in a const fn
+}
+
+const fn bar() -> i32 {
+    match 0 { 1 => 2, _ => 0 } //~ ERROR match expression is not allowed in a const fn
+}
 
 fn main() {}

src/test/ui/consts/const-loop.rs

@@ -1,13 +1,49 @@
+const _: () = loop {}; //~ ERROR loop is not allowed in a const
+
+static FOO: i32 = loop { break 4; }; //~ ERROR loop is not allowed in a static
+
+const fn foo() {
+    loop {} //~ ERROR loop is not allowed in a const fn
+}
+
+pub trait Foo {
+    const BAR: i32 = loop { break 4; }; //~ ERROR loop is not allowed in a const
+}
+
+impl Foo for () {
+    const BAR: i32 = loop { break 4; }; //~ ERROR loop is not allowed in a const
+}
+
+fn non_const_outside() {
+    const fn const_inside() {
+        loop {} //~ ERROR `loop` is not allowed in a `const fn`
+    }
+}
+
+const fn const_outside() {
+    fn non_const_inside() {
+        loop {}
+    }
+}
+
+fn main() {
+    let x = [0; {
+        while false {}
+        //~^ ERROR `while` is not allowed in a `const`
+        //~| ERROR constant contains unimplemented expression type
+        //~| ERROR constant contains unimplemented expression type
+        4
+    }];
+}
+
 const _: i32 = {
     let mut x = 0;
 
-    while x < 4 {
-        //~^ ERROR constant contains unimplemented expression type
-        //~| ERROR constant contains unimplemented expression type
+    while x < 4 { //~ ERROR while loop is not allowed in a const
         x += 1;
     }
 
-    while x < 8 {
+    while x < 8 { //~ ERROR while loop is not allowed in a const
         x += 1;
     }
 
@@ -17,16 +53,11 @@ const _: i32 = {
 const _: i32 = {
     let mut x = 0;
 
-    for i in 0..4 {
-        //~^ ERROR constant contains unimplemented expression type
-        //~| ERROR constant contains unimplemented expression type
-        //~| ERROR references in constants may only refer to immutable values
-        //~| ERROR calls in constants are limited to constant functions, tuple
-        //         structs and tuple variants
+    for i in 0..4 { //~ ERROR for loop is not allowed in a const
         x += i;
     }
 
-    for i in 0..4 {
+    for i in 0..4 { //~ ERROR for loop is not allowed in a const
         x += i;
     }
 
@@ -36,23 +67,26 @@ const _: i32 = {
 const _: i32 = {
     let mut x = 0;
 
-    loop {
+    loop { //~ ERROR loop is not allowed in a const
         x += 1;
-        if x == 4 {
-            //~^ ERROR constant contains unimplemented expression type
-            //~| ERROR constant contains unimplemented expression type
+        if x == 4 { //~ ERROR if expression is not allowed in a const
             break;
         }
     }
 
-    loop {
+    loop { //~ ERROR loop is not allowed in a const
         x += 1;
-        if x == 8 {
+        if x == 8 { //~ ERROR if expression is not allowed in a const
             break;
         }
     }
 
     x
 };
 
-fn main() {}
+const _: i32 = {
+    let mut x = 0;
+    while let None = Some(x) { } //~ ERROR while loop is not allowed in a const
+    while let None = Some(x) { } //~ ERROR while loop is not allowed in a const
+    x
+};