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Errors in a @constraints block reported with incorrect line numbers #1174

niclasmattsson opened this issue Feb 3, 2018 · 2 comments


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@niclasmattsson niclasmattsson commented Feb 3, 2018

If you make an error in a @constraints block the line number reported to cause the error is the line of the @constraints statement. For example:

m = Model(solver=ClpSolver())

@variables m begin
    0 <= x <= 4
    0 <= y <= 30

@constraints m begin        # <- error reported on this line
    region1, 1x + 5y <= 3.0
    region2, x - undeclared_variable <= 2.0

@objective(m, Max, 5x + 3y)

status = solve(m)

In this example the error is ERROR: LoadError: UndefVarError: undeclared_variable not defined, so you would easily find the problem anyway. But I often get more generic errors which don't have an immediately obvious cause, and if you have 20+ constraints then it becomes extremely difficult to identify the problem.

This greatly limits the usability of the @constraints syntax for large models - the precise situation in which it is intended to be convenient.


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@mlubin mlubin commented Feb 3, 2018

Thanks for the report. This should be fixed for JuMP 1.0 but has less priority than the ongoing MOI transition.


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@niclasmattsson niclasmattsson commented Feb 4, 2018

Excellent! No hurry, I want the MOI stuff and the changes to JuMPcontainers done before this too. :) But that said I'm glad to see you tagged this for the 1.0 release.

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