[ruby-core:82924] [Ruby trunk Bug#13928] Calling Integer.fdiv with BigDecimal returns unexpected result

Issue #13928 has been reported by [e-mail] (Carl Vander).

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Bug #13928: Calling Integer.fdiv with BigDecimal returns unexpected result
https://bugs.ruby-lang.org/issues/13928

* Author: [e-mail] (Carl Vander)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.4.2p198
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
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After upgrading a Rails project from 2.3.1 to 2.4.2 I ran into a number of failing tests. Seems like to behaviour of fdiv and conjuction with bigdecimal is wrong.

**Reproduce by running:**

irb(main):001:0> require 'bigdecimal'
=> true
irb(main):002:0> 1.fdiv(1-BigDecimal.new("0"))
=> 2.1296133346e-314

Ruby version: ruby 2.4.2p198 (2017-09-14 revision 59899) [x86_64-darwin16]

**I would expect the calculation to return 1, which is correctly done if converting the big decimal to a float first:**

irb(main):006:0> 1.fdiv(1-BigDecimal.new("0").to_f)
=> 1.0

**Using ruby 2.3.1p112, it also looks OK:**

irb(main):001:0> require 'bigdecimal'
=> true
irb(main):002:0> 1.fdiv(1-BigDecimal.new("0"))
=> #<BigDecimal:7fb6b8949690,'0.1E1',9(36)>
irb(main):003:0> 1.fdiv(1-BigDecimal.new("0")).to_i
=> 1





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