0000448: singleton warning generation ignores variables in quantifications

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Date Submitted

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0000448

mercury

Bug

public

2018-02-07 05:30

Reporter

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

assigned

Resolution

open

Product Version

Target Version

Fixed in Version

Summary

0000448: singleton warning generation ignores variables in quantifications

Description

The problem is that quantification replaces the list of variables being quantified
by a scope, ostensibly because that information is not needed by later compiler
passes. However, it *is* needed by the code that generates warnings for singleton
predicates.

As it is, we get bad singleton warnings for code such as

some [X] ( ... X ... )

and may NOT get singleton warnings for code such as

some [X] ( ... code in which there is no variable named X ... )

Steps To Reproduce

The two halves of the problem are demonstrated by the test cases
valid/bad_singleton_warning.m and warnings/missing_singleton_warning.m,
which I just added to the repository.

Additional Information

Simply keeping the quantified variables in place causes problems for later passes;
it is such code in these later passes that are the actual bugs.

Date Modified	Username	Field	Change
Issue History
2018-02-07 05:30	zs	New Issue
2018-02-07 05:30	zs	Status	new => assigned
2018-02-07 05:30	zs	Assigned To	=> zs

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