Low-provenance Expr->SyntaxTree conversion

Author: mlechu

src/JuliaLowering.jl

@@ -32,6 +32,7 @@ _include("runtime.jl")
 _include("syntax_macros.jl")
 
 _include("eval.jl")
+_include("compat.jl")
 
 function __init__()
     _register_kinds()

src/ast.jl

@@ -498,17 +498,20 @@ end
 # the middle of a pass.
 const CompileHints = Base.ImmutableDict{Symbol,Any}
 
-function setmeta(ex::SyntaxTree; kws...)
+function setmeta!(ex::SyntaxTree; kws...)
     @assert length(kws) == 1 # todo relax later ?
     key = first(keys(kws))
     value = first(values(kws))
     meta = begin
         m = get(ex, :meta, nothing)
         isnothing(m) ? CompileHints(key, value) : CompileHints(m, key, value)
     end
-    setattr(ex; meta=meta)
+    setattr!(ex; meta=meta)
+    ex
 end
 
+setmeta(ex::SyntaxTree; kws...) = setmeta!(copy_node(ex); kws...)
+
 function getmeta(ex::SyntaxTree, name::Symbol, default)
     meta = get(ex, :meta, nothing)
     isnothing(meta) ? default : get(meta, name, default)