ClojureScript

Combination of - and _ params causes JSC_DUPLICATE_PARAM

Details

  • Type: Defect Defect
  • Status: Open Open
  • Priority: Minor Minor
  • Resolution: Unresolved
  • Affects Version/s: None
  • Fix Version/s: None
  • Component/s: None
  • Labels:
    None

Description

The following function definitions each cause ERROR: JSC_DUPLICATE_PARAM. Parse error. Duplicate parameter name "_" at compile time with :advanced compilation:

Unable to find source-code formatter for language: clojure. Available languages are: javascript, sql, xhtml, actionscript, none, html, xml, java
(defn causes-duplicate-param [{_ :foo}]
  (reify
    Object
    (a-function [-]
      (fn [] "arbitrary function inside a-function body"))))

(defn causes-duplicate-param [{- :foo}]
  (reify
    Object
    (a-function [_]
      (fn [] "arbitrary function inside a-function body"))))

They generate, respectively:

duplicate_param_name_demo.core.t_duplicate_param_name_demo$core1601.prototype.a_function = ((function (map__1599,map__1599__$1,_){
return (function (){
var self__ = this;
var _ = this;
return ((function (_,map__1599,map__1599__$1,_){
return (function (){
return "arbitrary function inside a-function body";
});
;})(_,map__1599,map__1599__$1,_))
});})(map__1599,map__1599__$1,_))
;

duplicate_param_name_demo.core.t_duplicate_param_name_demo$core1612.prototype.a_function = ((function (map__1610,map__1610__$1,_){
return (function (){
var self__ = this;
var _ = this;
return ((function (_,map__1610,map__1610__$1,_){
return (function (){
return "arbitrary function inside a-function body";
});
;})(_,map__1610,map__1610__$1,_))
});})(map__1610,map__1610__$1,_))
;

(Notice the duplicate _ param on the 5th line of each.)

The following do not:

Unable to find source-code formatter for language: clojure. Available languages are: javascript, sql, xhtml, actionscript, none, html, xml, java
(defn causes-duplicate-param [{- :foo}]
  (reify
    Object
    (a-function [-]
      (fn [] "arbitrary function inside a-function body"))))

(defn causes-duplicate-param [{_ :foo}]
  (reify
    Object
    (a-function [_]
      (fn [] "arbitrary function inside a-function body"))))

They generate:

duplicate_param_name_demo.core.t_duplicate_param_name_demo$core1601.prototype.a_function = ((function (map__1599,map__1599__$1,_){
return (function (){
var self__ = this;
var ___$1 = this;
return ((function (___$1,map__1599,map__1599__$1,_){
return (function (){
return "arbitrary function inside a-function body";
});
;})(___$1,map__1599,map__1599__$1,_))
});})(map__1599,map__1599__$1,_))
;

duplicate_param_name_demo.core.t_duplicate_param_name_demo$core1612.prototype.a_function = ((function (map__1610,map__1610__$1,_){
return (function (){
var self__ = this;
var ___$1 = this;
return ((function (___$1,map__1610,map__1610__$1,_){
return (function (){
return "arbitrary function inside a-function body";
});
;})(___$1,map__1610,map__1610__$1,_))
});})(map__1610,map__1610__$1,_))
;

(Notice that one of the {} params has become __$1.)

My guess, though I haven't looked into the compiler code, is that the compiler escapes {} to _$1 when it would conflict with another {}, and also it translates - to {}, but it doesn't notice the conflict when the _ClojureScript symbols are different.

Activity

Hide
David Nolen added a comment -

This is because of munging they will become the same thing. Patch welcome.

Show
David Nolen added a comment - This is because of munging they will become the same thing. Patch welcome.
Hide
Peter Jaros added a comment -

Forgive the weird formatting errors. I couldn't find a preview function and there doesn't appear to be a way to edit the issue now that it's posted.

Show
Peter Jaros added a comment - Forgive the weird formatting errors. I couldn't find a preview function and there doesn't appear to be a way to edit the issue now that it's posted.

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Dates

  • Created:
    Updated: