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-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0015.md23
1 files changed, 8 insertions, 15 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0015.md b/compiler/rustc_error_codes/src/error_codes/E0015.md
index 021a0219d..ac78f66ad 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0015.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0015.md
@@ -1,5 +1,4 @@
-A constant item was initialized with something that is not a constant
-expression.
+A non-`const` function was called in a `const` context.
Erroneous code example:
@@ -8,26 +7,20 @@ fn create_some() -> Option<u8> {
Some(1)
}
-const FOO: Option<u8> = create_some(); // error!
+// error: cannot call non-const fn `create_some` in constants
+const FOO: Option<u8> = create_some();
```
-The only functions that can be called in static or constant expressions are
-`const` functions, and struct/enum constructors.
+All functions used in a `const` context (constant or static expression) must
+be marked `const`.
To fix this error, you can declare `create_some` as a constant function:
```
-const fn create_some() -> Option<u8> { // declared as a const function
+// declared as a `const` function:
+const fn create_some() -> Option<u8> {
Some(1)
}
-const FOO: Option<u8> = create_some(); // ok!
-
-// These are also working:
-struct Bar {
- x: u8,
-}
-
-const OTHER_FOO: Option<u8> = Some(1);
-const BAR: Bar = Bar {x: 1};
+const FOO: Option<u8> = create_some(); // no error!
```