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authorMazdak Farrokhzad <twingoow@gmail.com>2019-12-05 19:03:21 +0100
committerGitHub <noreply@github.com>2019-12-05 19:03:21 +0100
commita008aff0758268c03496d25686cf74e270cef8ba (patch)
tree2527eb2cfba3e52b99aa55f4f199e2a64ccfc67b
parentRollup merge of #67045 - Centril:parser-import-clean, r=Mark-Simulacrum (diff)
parentupdate comment to explain the importance of this check more clearly (diff)
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Rollup merge of #67055 - lqd:const_qualif, r=oli-obk
Make const-qualification look at more `const fn`s As explained in a lot more detail in #67053 this makes const-qualification not ignore the unstable const fns in libcore. r? @oli-obk cc @ecstatic-morse (Still a bit unsure about the `cfg`s here, for bootstrapping, does that seem correct ?) Fixes #67053.
-rw-r--r--src/libcore/lib.rs2
-rw-r--r--src/librustc_mir/transform/check_consts/mod.rs7
-rw-r--r--src/test/ui/consts/unstable-const-fn-in-libcore.rs29
-rw-r--r--src/test/ui/consts/unstable-const-fn-in-libcore.stderr22
4 files changed, 59 insertions, 1 deletions
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index ec19392..188ea1a 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -74,6 +74,8 @@
74#![feature(const_fn)] 74#![feature(const_fn)]
75#![feature(const_fn_union)] 75#![feature(const_fn_union)]
76#![feature(const_generics)] 76#![feature(const_generics)]
77#![cfg_attr(not(bootstrap), feature(const_ptr_offset_from))]
78#![cfg_attr(not(bootstrap), feature(const_type_name))]
77#![feature(custom_inner_attributes)] 79#![feature(custom_inner_attributes)]
78#![feature(decl_macro)] 80#![feature(decl_macro)]
79#![feature(doc_cfg)] 81#![feature(doc_cfg)]
diff --git a/src/librustc_mir/transform/check_consts/mod.rs b/src/librustc_mir/transform/check_consts/mod.rs
index 7095b3f..82ffafb 100644
--- a/src/librustc_mir/transform/check_consts/mod.rs
+++ b/src/librustc_mir/transform/check_consts/mod.rs
@@ -77,7 +77,12 @@ impl ConstKind {
77 let mode = match tcx.hir().body_owner_kind(hir_id) { 77 let mode = match tcx.hir().body_owner_kind(hir_id) {
78 HirKind::Closure => return None, 78 HirKind::Closure => return None,
79 79
80 HirKind::Fn if tcx.is_const_fn(def_id) => ConstKind::ConstFn, 80 // Note: this is deliberately checking for `is_const_fn_raw`, as the `is_const_fn`
81 // checks take into account the `rustc_const_unstable` attribute combined with enabled
82 // feature gates. Otherwise, const qualification would _not check_ whether this
83 // function body follows the `const fn` rules, as an unstable `const fn` would
84 // be considered "not const". More details are available in issue #67053.
85 HirKind::Fn if tcx.is_const_fn_raw(def_id) => ConstKind::ConstFn,
81 HirKind::Fn => return None, 86 HirKind::Fn => return None,
82 87
83 HirKind::Const => ConstKind::Const, 88 HirKind::Const => ConstKind::Const,
diff --git a/src/test/ui/consts/unstable-const-fn-in-libcore.rs b/src/test/ui/consts/unstable-const-fn-in-libcore.rs
new file mode 100644
index 0000000..cad1516
--- /dev/null
+++ b/src/test/ui/consts/unstable-const-fn-in-libcore.rs
@@ -0,0 +1,29 @@
1// This is a non-regression test for const-qualification of unstable items in libcore
2// as explained in issue #67053.
3// const-qualification could miss some `const fn`s if they were unstable and the feature
4// gate was not enabled in libcore.
5
6#![stable(feature = "core", since = "1.6.0")]
7#![feature(const_if_match)]
8#![feature(rustc_const_unstable)]
9#![feature(staged_api)]
10
11enum Opt<T> {
12 Some(T),
13 None,
14}
15
16impl<T> Opt<T> {
17 #[rustc_const_unstable(feature = "foo")]
18 #[stable(feature = "rust1", since = "1.0.0")]
19 const fn unwrap_or_else<F: FnOnce() -> T>(self, f: F) -> T {
20 //~^ ERROR destructors cannot be evaluated at compile-time
21 //~| ERROR destructors cannot be evaluated at compile-time
22 match self {
23 Opt::Some(t) => t,
24 Opt::None => f(), //~ ERROR E0015
25 }
26 }
27}
28
29fn main() {}
diff --git a/src/test/ui/consts/unstable-const-fn-in-libcore.stderr b/src/test/ui/consts/unstable-const-fn-in-libcore.stderr
new file mode 100644
index 0000000..a8455ce
--- /dev/null
+++ b/src/test/ui/consts/unstable-const-fn-in-libcore.stderr
@@ -0,0 +1,22 @@
1error[E0015]: calls in constant functions are limited to constant functions, tuple structs and tuple variants
2 --> $DIR/unstable-const-fn-in-libcore.rs:24:26
3 |
4LL | Opt::None => f(),
5 | ^^^
6
7error[E0493]: destructors cannot be evaluated at compile-time
8 --> $DIR/unstable-const-fn-in-libcore.rs:19:53
9 |
10LL | const fn unwrap_or_else<F: FnOnce() -> T>(self, f: F) -> T {
11 | ^ constant functions cannot evaluate destructors
12
13error[E0493]: destructors cannot be evaluated at compile-time
14 --> $DIR/unstable-const-fn-in-libcore.rs:19:47
15 |
16LL | const fn unwrap_or_else<F: FnOnce() -> T>(self, f: F) -> T {
17 | ^^^^ constant functions cannot evaluate destructors
18
19error: aborting due to 3 previous errors
20
21Some errors have detailed explanations: E0015, E0493.
22For more information about an error, try `rustc --explain E0015`.