Allow inline consts to reference generic params

Author: nbdd0121

compiler/rustc_resolve/src/late.rs

@@ -3101,6 +3101,13 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
         );
     }
 
+    fn resolve_inline_const(&mut self, constant: &'ast AnonConst) {
+        debug!("resolve_anon_const {constant:?}");
+        self.with_constant_rib(IsRepeatExpr::No, HasGenericParams::Yes, None, |this| {
+            visit::walk_anon_const(this, constant);
+        });
+    }
+
     fn resolve_expr(&mut self, expr: &'ast Expr, parent: Option<&'ast Expr>) {
         // First, record candidate traits for this expression if it could
         // result in the invocation of a method call.
@@ -3257,7 +3264,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 });
             }
             ExprKind::ConstBlock(ref ct) => {
-                self.resolve_anon_const(ct, IsRepeatExpr::No);
+                self.resolve_inline_const(ct);
             }
             ExprKind::Index(ref elem, ref idx) => {
                 self.resolve_expr(elem, Some(expr));

src/test/ui/inline-const/const-expr-generic-err.rs

@@ -0,0 +1,15 @@
+// build-fail
+#![feature(inline_const)]
+
+fn foo<T>() {
+    const { assert!(std::mem::size_of::<T>() == 0); } //~ ERROR E0080
+}
+
+fn bar<const N: usize>() -> usize {
+    const { N - 1 } //~ ERROR E0080
+}
+
+fn main() {
+    foo::<i32>();
+    bar::<0>();
+}

src/test/ui/inline-const/const-expr-generic-err.stderr

@@ -0,0 +1,29 @@
+error[E0080]: evaluation of `foo::<i32>::{constant#0}` failed
+  --> $DIR/const-expr-generic-err.rs:5:13
+   |
+LL |     const { assert!(std::mem::size_of::<T>() == 0); }
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'assertion failed: std::mem::size_of::<T>() == 0', $DIR/const-expr-generic-err.rs:5:13
+   |
+   = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn foo::<i32>`
+  --> $DIR/const-expr-generic-err.rs:13:5
+   |
+LL |     foo::<i32>();
+   |     ^^^^^^^^^^^^
+
+error[E0080]: evaluation of `bar::<0_usize>::{constant#0}` failed
+  --> $DIR/const-expr-generic-err.rs:9:13
+   |
+LL |     const { N - 1 }
+   |             ^^^^^ attempt to compute `0_usize - 1_usize`, which would overflow
+
+note: the above error was encountered while instantiating `fn bar::<0_usize>`
+  --> $DIR/const-expr-generic-err.rs:14:5
+   |
+LL |     bar::<0>();
+   |     ^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0080`.

src/test/ui/inline-const/const-expr-generic-err2.rs

@@ -0,0 +1,10 @@
+#![feature(inline_const)]
+
+fn foo<T>() {
+    let _ = [0u8; const { std::mem::size_of::<T>() }];
+    //~^ ERROR: constant expression depends on a generic parameter
+}
+
+fn main() {
+    foo::<i32>();
+}

src/test/ui/inline-const/const-expr-generic-err2.stderr

@@ -0,0 +1,10 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/const-expr-generic-err2.rs:4:19
+   |
+LL |     let _ = [0u8; const { std::mem::size_of::<T>() }];
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to previous error
+

src/test/ui/inline-const/const-expr-generic.rs

@@ -0,0 +1,15 @@
+// check-pass
+#![feature(inline_const)]
+
+fn foo<T>() -> usize {
+    const { std::mem::size_of::<T>() }
+}
+
+fn bar<const N: usize>() -> usize {
+    const { N + 1 }
+}
+
+fn main() {
+    foo::<i32>();
+    bar::<1>();
+}

src/test/ui/inline-const/const-match-pat-generic.rs

@@ -1,6 +1,5 @@
 #![allow(incomplete_features)]
 #![feature(inline_const_pat)]
-#![feature(generic_const_exprs)]
 
 // rust-lang/rust#82518: ICE with inline-const in match referencing const-generic parameter
 
@@ -16,7 +15,7 @@ const fn f(x: usize) -> usize {
     x + 1
 }
 
-fn bar<const V: usize>() where [(); f(V)]: {
+fn bar<const V: usize>() {
     match 0 {
         const { f(V) } => {},
         //~^ ERROR constant pattern depends on a generic parameter

src/test/ui/inline-const/const-match-pat-generic.stderr

@@ -1,17 +1,17 @@
 error[E0158]: const parameters cannot be referenced in patterns
-  --> $DIR/const-match-pat-generic.rs:9:9
+  --> $DIR/const-match-pat-generic.rs:8:9
    |
 LL |         const { V } => {},
    |         ^^^^^^^^^^^
 
 error: constant pattern depends on a generic parameter
-  --> $DIR/const-match-pat-generic.rs:21:9
+  --> $DIR/const-match-pat-generic.rs:20:9
    |
 LL |         const { f(V) } => {},
    |         ^^^^^^^^^^^^^^
 
 error: constant pattern depends on a generic parameter
-  --> $DIR/const-match-pat-generic.rs:21:9
+  --> $DIR/const-match-pat-generic.rs:20:9
    |
 LL |         const { f(V) } => {},
    |         ^^^^^^^^^^^^^^