Add @inline for anonymous functions

[ssikdar1]

Closes #34939

added a check for ex.head === :-> in findmeta so that @inline will work anonymous functions.

Testing

julia> @inline x -> x^2 + 2x - 1
#1 (generic function with 1 method)

julia> @inline x -> x
#3 (generic function with 1 method)

• Add a few tests.
  Added a test in test/compiler/inline.jl

• Add a NEWS item.

[fredrikekre]

Should we also look for

@inline f = x -> x

expressions?

[KristofferC]

IMO, that is not necessary, this doesn't work for example:

@inline g = function f(x) x end

Sure, you wouldn't write that but it still is easiest if the @inline is only applied to the function definition expression.

[JeffBezanson]

This doesn't test that the inline declaration has been applied to the inner function; it tests that the inlining pass produced valid output for test_outer2.

[ssikdar1]

@JeffBezanson
makes sense! How do I test if the inline declaration has been applied to the function?
Do I have to look at the Expr produced when using the inline macro?

julia> Base.parse_input_line("x -> x^2 + 2x - 1")
:($(Expr(:toplevel, :(#= none:1 =#), :((x->begin
          #= none:1 =#
          (x ^ 2 + 2x) - 1
      end)))))

julia> Base.parse_input_line("@inline x -> x^2 + 2x - 1")
:($(Expr(:toplevel, :(#= none:1 =#), :(#= none:1 =# @inline((x->begin
              #= none:1 =#
              (x ^ 2 + 2x) - 1
          end))))))

Something like this?

[JeffBezanson]

This is an easy way to test whether the inlining flag is set:

julia> ccall(:jl_ast_flag_inlineable, Bool, (Any,), first(methods(x->x)).source)
false

[ssikdar1]

@JeffBezanson
thanks! I added some tests to check :jl_ast_flag_inlineable for both anonymous and normal functions in b8ddf2a

[JeffBezanson]

This test can be removed.

[ssikdar1]

removed in 57ecb07

[JeffBezanson]

The ret variable is redundant here; can just do @test ccall(... etc. It is also more idiomatic to use @test x and @test !x instead of @test x == true.

[ssikdar1]

fixed in 57ecb07

[JeffBezanson]

Thanks for your patience in working through the review process @ssikdar1 ! LGTM now.