Rollup merge of rust-lang#61518 - czipperz:const-fn-doc-disallow-loops, r=Centril

Add loops to doc list of things not stable in const fn

Closes rust-lang#61508

Author: Centril

src/librustc_mir/transform/qualify_min_const_fn.rs

@@ -299,7 +299,7 @@ fn check_terminator(
 
         TerminatorKind::FalseEdges { .. } | TerminatorKind::SwitchInt { .. } => Err((
             span,
-            "`if`, `match`, `&&` and `||` are not stable in const fn".into(),
+            "loops and conditional expressions are not stable in const fn".into(),
         )),
         | TerminatorKind::Abort | TerminatorKind::Unreachable => {
             Err((span, "const fn with unreachable code is not stable".into()))

src/test/ui/consts/min_const_fn/min_const_fn.nll.stderr

@@ -160,7 +160,7 @@ LL | const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:100:38
    |
 LL | const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
@@ -169,7 +169,7 @@ LL | const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:102:29
    |
 LL | const fn foo30_5(b: bool) { while b { } }
@@ -178,7 +178,7 @@ LL | const fn foo30_5(b: bool) { while b { } }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:104:44
    |
 LL | const fn foo36(a: bool, b: bool) -> bool { a && b }
@@ -187,7 +187,7 @@ LL | const fn foo36(a: bool, b: bool) -> bool { a && b }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:106:44
    |
 LL | const fn foo37(a: bool, b: bool) -> bool { a || b }

src/test/ui/consts/min_const_fn/min_const_fn.rs

@@ -98,13 +98,13 @@ const fn foo30_2(x: *mut u32) -> usize { x as usize }
 const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize } }
 //~^ ERROR casting pointers to ints is unstable
 const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
-//~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
+//~^ ERROR loops and conditional expressions are not stable in const fn
 const fn foo30_5(b: bool) { while b { } } //~ ERROR not stable in const fn
 const fn foo30_6() -> bool { let x = true; x }
 const fn foo36(a: bool, b: bool) -> bool { a && b }
-//~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
+//~^ ERROR loops and conditional expressions are not stable in const fn
 const fn foo37(a: bool, b: bool) -> bool { a || b }
-//~^ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
+//~^ ERROR loops and conditional expressions are not stable in const fn
 const fn inc(x: &mut i32) { *x += 1 }
 //~^ ERROR mutable references in const fn are unstable
 

src/test/ui/consts/min_const_fn/min_const_fn.stderr

@@ -160,7 +160,7 @@ LL | const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:100:38
    |
 LL | const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
@@ -169,7 +169,7 @@ LL | const fn foo30_4(b: bool) -> usize { if b { 1 } else { 42 } }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:102:29
    |
 LL | const fn foo30_5(b: bool) { while b { } }
@@ -178,7 +178,7 @@ LL | const fn foo30_5(b: bool) { while b { } }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:104:44
    |
 LL | const fn foo36(a: bool, b: bool) -> bool { a && b }
@@ -187,7 +187,7 @@ LL | const fn foo36(a: bool, b: bool) -> bool { a && b }
    = note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
    = help: add #![feature(const_fn)] to the crate attributes to enable
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/min_const_fn.rs:106:44
    |
 LL | const fn foo37(a: bool, b: bool) -> bool { a || b }

src/test/ui/consts/single_variant_match_ice.rs

@@ -15,7 +15,7 @@ impl Foo {
         use self::Foo::*;
 
         match *self {
-            Prob => 0x1, //~ ERROR `if`, `match`, `&&` and `||` are not stable in const fn
+            Prob => 0x1, //~ ERROR loops and conditional expressions are not stable in const fn
         }
     }
 }

src/test/ui/consts/single_variant_match_ice.stderr

@@ -10,7 +10,7 @@ error[E0019]: constant contains unimplemented expression type
 LL |     x => 42,
    |     ^
 
-error[E0723]: `if`, `match`, `&&` and `||` are not stable in const fn
+error[E0723]: loops and conditional expressions are not stable in const fn
   --> $DIR/single_variant_match_ice.rs:18:13
    |
 LL |             Prob => 0x1,