Merge pull request #62215 from eeckstein/fix-inline-attribute-docs

docs: fix documentation for the `@inline` attribute

Author: eeckstein

docs/ReferenceGuides/UnderscoredAttributes.md

@@ -535,6 +535,15 @@ initializers from its superclass. This implies that all designated initializers
 overridden. This attribute is often printed alongside
 `@_hasMissingDesignatedInitializers` in this case.
 
+## `@inline(__always)`
+
+Forces the function to be inlined.
+
+If it's not possible to always inline the function, e.g. if it's a self-
+recursive function, the attribute is ignored.
+
+This attribute has no effect in debug builds.
+
 ## `@_noEagerMove`
 
 When applied to a value, indicates that the value's lifetime is lexical, that

docs/SIL.rst

@@ -1070,14 +1070,14 @@ The minimal OS-version where the function is available.
 ::
 
   sil-function-attribute ::= '[' sil-function-inlining ']'
-  sil-function-inlining ::= 'never'
+  sil-function-inlining ::= 'noinline'
 
 The function is never inlined.
 ::
 
-  sil-function-inlining ::= 'always'
+  sil-function-inlining ::= 'always_inline'
 
-The function is always inlined, even in a ``Onone`` build.
+The function is always inlined.
 ::
 
   sil-function-attribute ::= '[' sil-function-optimization ']'