Rollup merge of rust-lang#111928 - c410-f3r:dqewdas, r=eholk

[RFC-2011] Expand more expressions

cc rust-lang#44838

Expands `if`, `let`, `match` and also makes `generic_assert_internals` an allowed feature when using `assert!`. `#![feature(generic_assert)]` is still needed to activate everything.

```rust
#![feature(generic_assert)]

fn fun(a: Option<i32>, b: Option<i32>, c: Option<i32>) {
  assert!(
    if a.is_some() { 1 } else { 2 } == 3
      && if let Some(elem) = b { elem == 4 } else { false }
      && match c { Some(_) => true, None => false }
  );
}

fn main() {
  fun(Some(1), None, Some(2));
}

// Assertion failed: assert!(
//   if a.is_some() { 1 } else { 2 } == 3
//     && if let Some(elem) = b { elem == 4 } else { false }
//     && match c { Some(_) => true, None => false }
// );
//
// With captures:
//   a = Some(1)
//   b = None
//   c = Some(2)
```

compiler/rustc_builtin_macros/src/assert/context.rs

@@ -233,10 +233,19 @@ impl<'cx, 'a> Context<'cx, 'a> {
             ExprKind::Cast(local_expr, _) => {
                 self.manage_cond_expr(local_expr);
             }
+            ExprKind::If(local_expr, _, _) => {
+                self.manage_cond_expr(local_expr);
+            }
             ExprKind::Index(prefix, suffix) => {
                 self.manage_cond_expr(prefix);
                 self.manage_cond_expr(suffix);
             }
+            ExprKind::Let(_, local_expr, _) => {
+                self.manage_cond_expr(local_expr);
+            }
+            ExprKind::Match(local_expr, _) => {
+                self.manage_cond_expr(local_expr);
+            }
             ExprKind::MethodCall(call) => {
                 for arg in &mut call.args {
                     self.manage_cond_expr(arg);
@@ -295,17 +304,14 @@ impl<'cx, 'a> Context<'cx, 'a> {
             | ExprKind::Continue(_)
             | ExprKind::Err
             | ExprKind::Field(_, _)
-            | ExprKind::FormatArgs(_)
             | ExprKind::ForLoop(_, _, _, _)
-            | ExprKind::If(_, _, _)
+            | ExprKind::FormatArgs(_)
             | ExprKind::IncludedBytes(..)
             | ExprKind::InlineAsm(_)
-            | ExprKind::OffsetOf(_, _)
-            | ExprKind::Let(_, _, _)
             | ExprKind::Lit(_)
             | ExprKind::Loop(_, _, _)
             | ExprKind::MacCall(_)
-            | ExprKind::Match(_, _)
+            | ExprKind::OffsetOf(_, _)
             | ExprKind::Path(_, _)
             | ExprKind::Ret(_)
             | ExprKind::Try(_)

library/core/src/macros/mod.rs

@@ -1427,7 +1427,7 @@ pub(crate) mod builtin {
     #[rustc_builtin_macro]
     #[macro_export]
     #[rustc_diagnostic_item = "assert_macro"]
-    #[allow_internal_unstable(core_panic, edition_panic)]
+    #[allow_internal_unstable(core_panic, edition_panic, generic_assert_internals)]
     macro_rules! assert {
         ($cond:expr $(,)?) => {{ /* compiler built-in */ }};
         ($cond:expr, $($arg:tt)+) => {{ /* compiler built-in */ }};

tests/ui/macros/rfc-2011-nicer-assert-messages/all-expr-kinds.rs

@@ -5,7 +5,7 @@
 // needs-unwind Asserting on contents of error message
 
 #![allow(path_statements, unused_allocation)]
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 macro_rules! test {
   (
@@ -51,6 +51,7 @@ macro_rules! tests {
 
 const FOO: Foo = Foo { bar: 1 };
 
+
 #[derive(Clone, Copy, Debug, PartialEq)]
 struct Foo {
   bar: i32
@@ -83,9 +84,18 @@ fn main() {
     // cast
     [ elem as i32 == 3 ] => "Assertion failed: elem as i32 == 3\nWith captures:\n  elem = 1\n"
 
+    // if
+    [ if elem == 3 { true } else { false } ] => "Assertion failed: if elem == 3 { true } else { false }\nWith captures:\n  elem = 1\n"
+
     // index
     [ [1i32, 1][elem as usize] == 3 ] => "Assertion failed: [1i32, 1][elem as usize] == 3\nWith captures:\n  elem = 1\n"
 
+    // let
+    [ if let 3 = elem { true } else { false } ] => "Assertion failed: if let 3 = elem { true } else { false }\nWith captures:\n  elem = 1\n"
+
+    // match
+    [ match elem { 3 => true, _ => false, } ] => "Assertion failed: match elem { 3 => true, _ => false, }\nWith captures:\n  elem = 1\n"
+
     // method call
     [ FOO.add(elem, elem) == 3 ] => "Assertion failed: FOO.add(elem, elem) == 3\nWith captures:\n  elem = 1\n"
 
@@ -107,77 +117,4 @@ fn main() {
     // unary
     [ -elem == -3 ] => "Assertion failed: -elem == -3\nWith captures:\n  elem = 1\n"
   );
-
-  // ***** Disallowed *****
-
-  tests!(
-    let mut elem = 1i32;
-
-    // assign
-    [ { let local = elem; local } == 3 ] => "Assertion failed: { let local = elem; local } == 3"
-
-    // assign op
-    [ { elem += 1; elem } == 3 ] => "Assertion failed: { elem += 1; elem } == 3"
-
-    // async
-    [ { let _ = async { elem }; elem } == 3 ] => "Assertion failed: { let _ = async { elem }; elem } == 3"
-
-    // await
-
-    // block
-    [ { elem } == 3 ] => "Assertion failed: { elem } == 3"
-
-    // break
-    [ loop { break elem; } ==  3 ] => "Assertion failed: loop { break elem; } == 3"
-
-    // closure
-    [(|| elem)() ==  3 ] => "Assertion failed: (|| elem)() == 3"
-
-    // const block
-
-    // continue
-
-    // err
-
-    // field
-    [ FOO.bar ==  3 ] => "Assertion failed: FOO.bar == 3"
-
-    // for loop
-    [ { for _ in 0..elem { elem; } elem } ==  3 ] => "Assertion failed: { for _ in 0..elem { elem; } elem } == 3"
-
-    // if
-    [ if true { elem } else { elem } == 3 ] => "Assertion failed: if true { elem } else { elem } == 3"
-
-    // inline asm
-
-    // let
-    [ if let true = true { elem } else { elem } == 3 ] => "Assertion failed: if let true = true { elem } else { elem } == 3"
-
-    // lit
-
-    // loop
-    [ loop { elem; break elem; } == 3 ] => "Assertion failed: loop { elem; break elem; } == 3"
-
-    // mac call
-
-    // match
-    [ match elem { _ => elem } == 3 ] => "Assertion failed: (match elem { _ => elem, }) == 3"
-
-    // ret
-    [ (|| { return elem; })() == 3 ] => "Assertion failed: (|| { return elem; })() == 3"
-
-    // try
-    [ (|| { Some(Some(elem)?) })() == Some(3) ] => "Assertion failed: (|| { Some(Some(elem)?) })() == Some(3)"
-
-    // try block
-
-    // underscore
-
-    // while
-    [ { while false { elem; break; } elem } == 3 ] => "Assertion failed: { while false { elem; break; } elem } == 3"
-
-    // yeet
-
-    // yield
-  );
 }

tests/ui/macros/rfc-2011-nicer-assert-messages/all-not-available-cases.rs

@@ -4,7 +4,7 @@
 // run-pass
 // needs-unwind Asserting on contents of error message
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 extern crate common;
 

tests/ui/macros/rfc-2011-nicer-assert-messages/assert-with-custom-errors-does-not-create-unnecessary-code.rs

@@ -1,7 +1,7 @@
 // compile-flags: --test
 // run-pass
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 #[should_panic(expected = "Custom user message")]
 #[test]

tests/ui/macros/rfc-2011-nicer-assert-messages/assert-without-captures-does-not-create-unnecessary-code.rs

@@ -3,7 +3,7 @@
 // run-pass
 // needs-unwind Asserting on contents of error message
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 extern crate common;
 

tests/ui/macros/rfc-2011-nicer-assert-messages/feature-gate-generic_assert.rs

@@ -2,7 +2,7 @@
 // ignore-tidy-linelength
 // run-pass
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 use std::fmt::{Debug, Formatter};
 

tests/ui/macros/rfc-2011-nicer-assert-messages/non-consuming-methods-have-optimized-codegen.rs

@@ -1,7 +1,7 @@
 // check-pass
 // compile-flags: -Z unpretty=expanded
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 
 fn arbitrary_consuming_method_for_demonstration_purposes() {
     let elem = 1i32;

tests/ui/macros/rfc-2011-nicer-assert-messages/non-consuming-methods-have-optimized-codegen.stdout

@@ -3,7 +3,7 @@
 // check-pass
 // compile-flags: -Z unpretty=expanded
 
-#![feature(core_intrinsics, generic_assert, generic_assert_internals)]
+#![feature(core_intrinsics, generic_assert)]
 #[prelude_import]
 use ::std::prelude::rust_2015::*;
 #[macro_use]