defprotocol: invalid method overload syntax getting accepted
Description
The compiler accepts this erroneous form:
Analysis: defprotocol silently assoc's the last list of signatures found for any particular method name, without checking whether the method name was given earlier.
Patch: clj-1056-2.diff
Approach: Modify defprotocol to check whether each method name has already been encountered earlier, and throw an exception if so. The patch also updates the error message for the case of a protocol function with no args specified.
Behavior with patch clj-1056-2.txt:
Screened by: Stuart Halloway
Environment
Activity
Can not reproduce the fist error:
user=> (defprotocol Foo (f ([this]) ([this arg])))
CompilerException java.lang.IllegalArgumentException: Parameter declaration missing, compilingNO_SOURCE_PATH:5:1)
But the 2nd one I can reproduce:
user=> (defprotocol Bar (m [this]) (m [this arg]))
Bar
user=> Bar
{:on-interface user.Bar, :on user.Bar, :sigs {:m {:doc nil, :arglists ([this arg]), :name m}}, :var #'user/Bar, :method-map {:m :m}, :method-builders {#'user/m #<user$eval71$fn_72 user$eval71$fn_72@1a2b53fb>}}
user=>
Notice that :arglists only has one entry
Vetting
Moving back to Triaged as Rich has not vetted.
Patch clj-1056-1.txt changes defprotocol to throw an exception if the same method name appears more than once.
Without this patch, the last set of signatures for a method name "wins", silently overriding any earlier ones.
Updated patch to improve error messages and to switch from CompilerException (which is not used outside the Compiler) back to IllegalArgumentException.
I think it would be a good idea to have a general Exception that could carry file/line/col info that could be used by Compiler but also other errors (the EdnReader and LispReader both have their own variants). But I think that should be a separate enhancement, which I have filed as CLJ-1280.
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