inference: minor code quality improvements

(cherry picked from commit a229f86)

Author: aviatesk

base/compiler/abstractinterpretation.jl

@@ -1186,9 +1186,9 @@ function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e),
         if length(e.args) == 2 && isconcretetype(t) && !t.mutable
             at = abstract_eval_value(interp, e.args[2], vtypes, sv)
             n = fieldcount(t)
-            if isa(at, Const) && isa(at.val, Tuple) && n == length(at.val) &&
-                let t = t, at = at; _all(i->at.val[i] isa fieldtype(t, i), 1:n); end
-                t = Const(ccall(:jl_new_structt, Any, (Any, Any), t, at.val))
+            if isa(at, Const) && (val = at.val; isa(val, Tuple)) && n == length(val) &&
+                let t = t, val = val; _all(i->val[i] isa fieldtype(t, i), 1:n); end
+                t = Const(ccall(:jl_new_structt, Any, (Any, Any), t, val))
             elseif isa(at, PartialStruct) && at ⊑ Tuple && n == length(at.fields) &&
                 let t = t, at = at; _all(i->at.fields[i] ⊑ fieldtype(t, i), 1:n); end
                 t = PartialStruct(t, at.fields)

base/compiler/tfuncs.jl

@@ -1612,7 +1612,7 @@ function return_type_tfunc(interp::AbstractInterpreter, argtypes::Vector{Any}, s
                     if contains_is(argtypes_vec, Union{})
                         return Const(Union{})
                     end
-                    rt = abstract_call(interp, nothing, argtypes_vec, sv, -1).rt
+                    rt = widenconditional(abstract_call(interp, nothing, argtypes_vec, sv, -1).rt)
                     if isa(rt, Const)
                         # output was computed to be constant
                         return Const(typeof(rt.val))

base/compiler/typeinfer.jl

@@ -792,7 +792,8 @@ function typeinf_ext(interp::AbstractInterpreter, mi::MethodInstance)
             if invoke_api(code) == 2
                 i == 2 && ccall(:jl_typeinf_end, Cvoid, ())
                 tree = ccall(:jl_new_code_info_uninit, Ref{CodeInfo}, ())
-                tree.code = Any[ ReturnNode(quoted(code.rettype_const)) ]
+                rettype_const = code.rettype_const
+                tree.code = Any[ ReturnNode(quoted(rettype_const)) ]
                 nargs = Int(method.nargs)
                 tree.slotnames = ccall(:jl_uncompress_argnames, Vector{Symbol}, (Any,), method.slot_syms)
                 tree.slotflags = fill(0x00, nargs)
@@ -804,7 +805,7 @@ function typeinf_ext(interp::AbstractInterpreter, mi::MethodInstance)
                 tree.pure = true
                 tree.inlineable = true
                 tree.parent = mi
-                tree.rettype = Core.Typeof(code.rettype_const)
+                tree.rettype = Core.Typeof(rettype_const)
                 tree.min_world = code.min_world
                 tree.max_world = code.max_world
                 return tree