Add @inline for anonymous functions (JuliaLang#34953)

* Add @inline for anonymous functions

Co-authored-by: Rafael Fourquet <[email protected]>

NEWS.md

@@ -40,6 +40,8 @@ Language changes
 
 * The syntax `(;)` (which was deprecated in v1.4) now creates an empty named tuple ([#30115]).
 
+* `@inline` macro can now be applied to short-form anonymous functions ([#34953]).
+
 * In triple-quoted string literals, whitespace stripping is now done before processing
   escape sequences instead of after. For example, the syntax
   ```
@@ -50,6 +52,7 @@ Language changes
   Now the result is "a\n b", since the space before `b` is no longer considered to occur
   at the start of a line. The old behavior is considered a bug ([#35001]).
 
+
 Multi-threading changes
 -----------------------
 

base/expr.jl

@@ -332,7 +332,7 @@ function is_short_function_def(ex)
 end
 
 function findmeta(ex::Expr)
-    if ex.head === :function || is_short_function_def(ex)
+    if ex.head === :function || is_short_function_def(ex) || ex.head === :->
         body::Expr = ex.args[2]
         body.head === :block || error(body, " is not a block expression")
         return findmeta_block(ex.args)

test/compiler/inline.jl

@@ -275,3 +275,10 @@ let ci = code_typed(f34900, Tuple{Int, Int})[1].first
     @test length(ci.code) == 1 && isexpr(ci.code[1], :return) &&
         ci.code[1].args[1].id == 2
 end
+
+@testset "check jl_ast_flag_inlineable for inline macro" begin
+    @test ccall(:jl_ast_flag_inlineable, Bool, (Any,), first(methods(@inline x -> x)).source)
+    @test !ccall(:jl_ast_flag_inlineable, Bool, (Any,), first(methods( x -> x)).source)
+    @test ccall(:jl_ast_flag_inlineable, Bool, (Any,), first(methods(@inline function f(x) x end)).source)
+    @test !ccall(:jl_ast_flag_inlineable, Bool, (Any,), first(methods(function f(x) x end)).source)
+end