Do not promote constants that contain unpromotable code

rust-lang · Jun 15, 2018 · e76172c · e76172c
1 parent 5205ae8
commit e76172c
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Showing 11 changed files with 99 additions and 106 deletions.
diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
@@ -566,14 +566,15 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
 
                         ProjectionElem::Field(..) |
                         ProjectionElem::Index(_) => {
-                            if this.mode == Mode::Fn {
-                                let base_ty = proj.base.ty(this.mir, this.tcx).to_ty(this.tcx);
-                                if let Some(def) = base_ty.ty_adt_def() {
-                                    if def.is_union() {
-                                        this.not_const();
-                                    }
+                            let base_ty = proj.base.ty(this.mir, this.tcx).to_ty(this.tcx);
+                            // accessing union fields is never allowed inside promoteds
+                            if let Some(def) = base_ty.ty_adt_def() {
+                                if def.is_union() {
+                                    this.add(Qualif::NOT_PROMOTABLE);
                                 }
-                            } else if this.qualif.intersects(Qualif::STATIC) {
+                            }
+                            // Only functions may refer to statics directly
+                            if this.mode != Mode::Fn && this.qualif.intersects(Qualif::STATIC) {
                                 span_err!(this.tcx.sess, this.span, E0494,
                                           "cannot refer to the interior of another \
                                            static, use a constant instead");
@@ -615,6 +616,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                 } = constant.literal {
                     // Don't peek inside trait associated constants.
                     if self.tcx.trait_of_item(def_id).is_some() {
+                        self.add(Qualif::NOT_PROMOTABLE);
                         self.add_type(ty);
                     } else {
                         let (bits, _) = self.tcx.at(constant.span).mir_const_qualif(def_id);

diff --git a/src/librustc_passes/rvalue_promotion.rs b/src/librustc_passes/rvalue_promotion.rs
@@ -267,7 +267,7 @@ impl<'a, 'tcx> Visitor<'tcx> for CheckCrateVisitor<'a, 'tcx> {
         }
 
         if self.promotable {
-            self.result.insert(ex.hir_id.local_id);
+            assert!(self.result.insert(ex.hir_id.local_id));
         }
         self.promotable &= outer;
     }
@@ -361,17 +361,14 @@ fn check_expr<'a, 'tcx>(v: &mut CheckCrateVisitor<'a, 'tcx>, e: &hir::Expr, node
 
                 Def::Const(did) |
                 Def::AssociatedConst(did) => {
-                    let promotable = if v.tcx.trait_of_item(did).is_some() {
+                    if v.tcx.trait_of_item(did).is_some() {
                         // Don't peek inside trait associated constants.
-                        false
+                        v.promotable = false;
                     } else {
-                        v.tcx.at(e.span).const_is_rvalue_promotable_to_static(did)
-                    };
-
-                    // Just in case the type is more specific than the definition,
-                    // e.g. impl associated const with type parameters, check it.
-                    // Also, trait associated consts are relaxed by this.
-                    v.promotable &= promotable || v.type_has_only_promotable_values(node_ty);
+                        // Just in case the type is more specific than the definition,
+                        // e.g. impl associated const with type parameters, check it.
+                        v.promotable &= v.tcx.at(e.span).const_is_rvalue_promotable_to_static(did);
+                    }
                 }
 
                 _ => {

diff --git a/src/test/ui/const-eval/issue-44578.nll.stderr b/src/test/ui/const-eval/issue-44578.nll.stderr
diff --git a/src/test/ui/const-eval/issue-44578.rs b/src/test/ui/const-eval/issue-44578.rs
@@ -12,6 +12,7 @@
 
 trait Foo {
     const AMT: usize;
+    //~^ ERROR E0080
 }
 
 enum Bar<A, B> {
@@ -20,7 +21,7 @@ enum Bar<A, B> {
 }
 
 impl<A: Foo, B: Foo> Foo for Bar<A, B> {
-    const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize];
+    const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize]; //~ ERROR E0080
 }
 
 impl Foo for u8 {
@@ -33,6 +34,4 @@ impl Foo for u16 {
 
 fn main() {
     println!("{}", <Bar<u16, u8> as Foo>::AMT);
-    //~^ ERROR erroneous constant used
-    //~| ERROR E0080
 }
diff --git a/src/test/ui/const-eval/issue-44578.stderr b/src/test/ui/const-eval/issue-44578.stderr
@@ -1,17 +1,17 @@
-error[E0080]: referenced constant
-  --> $DIR/issue-44578.rs:35:20
+error[E0080]: constant evaluation error
+  --> $DIR/issue-44578.rs:24:24
    |
-LL |     const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize];
-   |                        ------------------------------------ index out of bounds: the len is 1 but the index is 1
-...
-LL |     println!("{}", <Bar<u16, u8> as Foo>::AMT);
-   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize]; //~ ERROR E0080
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ index out of bounds: the len is 1 but the index is 1
 
-error[E0080]: erroneous constant used
-  --> $DIR/issue-44578.rs:35:20
+error[E0080]: constant evaluation error
+  --> $DIR/issue-44578.rs:14:5
    |
-LL |     println!("{}", <Bar<u16, u8> as Foo>::AMT);
-   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
+LL |     const AMT: usize;
+   |     ^^^^^^^^^^^^^^^^^
+...
+LL |     const AMT: usize = [A::AMT][(A::AMT > B::AMT) as usize]; //~ ERROR E0080
+   |                        ------------------------------------ index out of bounds: the len is 1 but the index is 1
 
 error: aborting due to 2 previous errors
 

diff --git a/src/test/ui/const-eval/issue-50814-2.rs b/src/test/ui/const-eval/issue-50814-2.rs
@@ -23,8 +23,7 @@ impl<T: C> Foo<T> for A<T> {
 }
 
 fn foo<T: C>() -> &'static usize {
-    &<A<T> as Foo<T>>::BAR //~ ERROR erroneous constant used
-//~| ERROR E0080
+    &<A<T> as Foo<T>>::BAR //~ ERROR borrowed value does not live long enough
 }
 
 impl C for () {

diff --git a/src/test/ui/const-eval/issue-50814-2.stderr b/src/test/ui/const-eval/issue-50814-2.stderr
@@ -1,20 +1,13 @@
-error[E0080]: referenced constant
-  --> $DIR/issue-50814-2.rs:26:5
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/issue-50814-2.rs:26:6
    |
-LL |     const BAR: usize = [5, 6, 7][T::BOO];
-   |                        ----------------- index out of bounds: the len is 3 but the index is 42
-...
-LL |     &<A<T> as Foo<T>>::BAR //~ ERROR erroneous constant used
-   |     ^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0080]: erroneous constant used
-  --> $DIR/issue-50814-2.rs:26:5
+LL |     &<A<T> as Foo<T>>::BAR //~ ERROR borrowed value does not live long enough
+   |      ^^^^^^^^^^^^^^^^^^^^^ temporary value does not live long enough
+LL | }
+   | - temporary value only lives until here
    |
-LL |     &<A<T> as Foo<T>>::BAR //~ ERROR erroneous constant used
-   |     ^---------------------
-   |      |
-   |      referenced constant has errors
+   = note: borrowed value must be valid for the static lifetime...
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0080`.
+For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/const-eval/issue-50814.rs b/src/test/ui/const-eval/issue-50814.rs
@@ -24,8 +24,7 @@ impl<A: Unsigned, B: Unsigned> Unsigned for Sum<A,B> {
 }
 
 fn foo<T>(_: T) -> &'static u8 {
-    &Sum::<U8,U8>::MAX //~ ERROR erroneous constant used
-//~| ERROR E0080
+    &Sum::<U8,U8>::MAX //~ ERROR borrowed value does not live long enough
 }
 
 fn main() {

diff --git a/src/test/ui/const-eval/issue-50814.stderr b/src/test/ui/const-eval/issue-50814.stderr
@@ -1,20 +1,13 @@
-error[E0080]: referenced constant
-  --> $DIR/issue-50814.rs:27:5
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/issue-50814.rs:27:6
    |
-LL |     const MAX: u8 = A::MAX + B::MAX;
-   |                     --------------- attempt to add with overflow
-...
-LL |     &Sum::<U8,U8>::MAX //~ ERROR erroneous constant used
-   |     ^^^^^^^^^^^^^^^^^^
-
-error[E0080]: erroneous constant used
-  --> $DIR/issue-50814.rs:27:5
+LL |     &Sum::<U8,U8>::MAX //~ ERROR borrowed value does not live long enough
+   |      ^^^^^^^^^^^^^^^^^ temporary value does not live long enough
+LL | }
+   | - temporary value only lives until here
    |
-LL |     &Sum::<U8,U8>::MAX //~ ERROR erroneous constant used
-   |     ^-----------------
-   |      |
-   |      referenced constant has errors
+   = note: borrowed value must be valid for the static lifetime...
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0080`.
+For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/const-eval/unpromotable_constant.rs b/src/test/ui/const-eval/unpromotable_constant.rs
@@ -0,0 +1,26 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(const_err)]
+
+union Bad {
+    usize: usize,
+    ptr: &'static u32,
+}
+
+const FOO: usize = unsafe {
+    Bad { ptr: &1 }.usize
+};
+
+
+fn main() {
+    let x: &'static usize = &FOO; //~ ERROR does not live long enough
+    let y: &'static usize = &(FOO % 42); //~ ERROR does not live long enough
+}
diff --git a/src/test/ui/const-eval/unpromotable_constant.stderr b/src/test/ui/const-eval/unpromotable_constant.stderr
@@ -0,0 +1,24 @@
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/unpromotable_constant.rs:24:30
+   |
+LL |     let x: &'static usize = &FOO; //~ ERROR does not live long enough
+   |                              ^^^ temporary value does not live long enough
+LL |     let y: &'static usize = &(FOO % 42); //~ ERROR does not live long enough
+LL | }
+   | - temporary value only lives until here
+   |
+   = note: borrowed value must be valid for the static lifetime...
+
+error[E0597]: borrowed value does not live long enough
+  --> $DIR/unpromotable_constant.rs:25:30
+   |
+LL |     let y: &'static usize = &(FOO % 42); //~ ERROR does not live long enough
+   |                              ^^^^^^^^^^ temporary value does not live long enough
+LL | }
+   | - temporary value only lives until here
+   |
+   = note: borrowed value must be valid for the static lifetime...
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0597`.