[SR-9609] Float80.init(_ other: Double) is called on passing float literal to Float80.init(_:)

[norio-nomura]

Previous ID	SR-9609
Radar	None
Original Reporter	@norio-nomura
Type	Bug
Status	Resolved
Resolution	Invalid

Environment

swift-4.2.1-RELEASE
swift-DEVELOPMENT-SNAPSHOT-2019-01-05-a
swift-5.0-DEVELOPMENT-SNAPSHOT-2019-01-04-a

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, TypeChecker
Assignee	None
Priority	Medium

md5: c995a995369ba536b9298a0306bfdc5f

Issue Description:

$ docker run --privileged -it --rm norionomura/swift:20190105a swift
Welcome to Swift version 5.0-dev (LLVM f63b283c71, Clang 41ac4c4262, Swift bbfc0649ed).
Type :help for assistance.
  1> import Foundation 
  2. let a = Float80.init(6.8523015e+5) 
  3. let b = 6.8523015e+5 as Float80 
  4. print(a) 
  5. print(b) 
  6. print(a == b)
685230.1500000000233
685230.15
false
a: Float80 = 685230.150000000023283
b: Float80 = 685230.149999999999977
  7>  

ast:

$ docker run --privileged -it --rm norionomura/swift:20190105a
root@92211f3075d3:/# echo "import Foundation; _ = Float80.init(6.8523015e+5)"|swift -frontend -dump-ast -
(source_file "<stdin>"
  (import_decl range=[<stdin>:1:1 - line:1:8] trailing_semi 'Foundation')
  (top_level_code_decl range=[<stdin>:1:20 - line:1:49]
    (brace_stmt range=[<stdin>:1:20 - line:1:49]
      (assign_expr type='()' location=<stdin>:1:22 range=[<stdin>:1:20 - line:1:49]
        (discard_assignment_expr type='@lvalue Float80' location=<stdin>:1:20 range=[<stdin>:1:20 - line:1:20])
        (call_expr type='Float80' location=<stdin>:1:32 range=[<stdin>:1:24 - line:1:49] nothrow arg_labels=_:
          (constructor_ref_call_expr type='(Double) -> Float80' location=<stdin>:1:32 range=[<stdin>:1:24 - line:1:32] nothrow
            (declref_expr type='(Float80.Type) -> (Double) -> Float80' location=<stdin>:1:32 range=[<stdin>:1:32 - line:1:32] decl=Swift.(file).Float80 extension.init(_:) function_ref=double)
            (type_expr type='Float80.Type' location=<stdin>:1:24 range=[<stdin>:1:24 - line:1:24] typerepr='Float80'))
          (paren_expr type='(Double)' location=<stdin>:1:37 range=[<stdin>:1:36 - line:1:49]
            (call_expr implicit type='Double' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] nothrow arg_labels=_builtinFloatLiteral:
              (constructor_ref_call_expr implicit type='(FPIEEE80) -> Double' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] nothrow
                (declref_expr implicit type='(Double.Type) -> (FPIEEE80) -> Double' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] decl=Swift.(file).Double extension.init(_builtinFloatLiteral:) function_ref=single)
                (type_expr implicit type='Double.Type' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] typerepr='Double'))
              (tuple_expr implicit type='(_builtinFloatLiteral: FPIEEE80)' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] names=_builtinFloatLiteral
                (float_literal_expr type='FPIEEE80' location=<stdin>:1:37 range=[<stdin>:1:37 - line:1:37] value=6.8523015e+5)))))))))

[belkadan]

This is correct behavior. Per SE-0213, construction syntax is only treated as equivalent to as when you just use the name of the type; adding init indicates that you really do want to call an initializer.

[norio-nomura]

Hm, that's strange. Our code didn't use init, but that was affected by this issue.
jpsim/Yams@e829e15

[belkadan]

SE-0213 is new behavior in Swift 5; prior to that, it was always construction syntax and never equivalent to as.

[norio-nomura]

Ah, I confirmed that Swift 5.0 is working as described in SE-0213 and Swift 4.2.1 is not.
Thanks! 🙂

$ swift
swift_oss_helper command enabled.
Welcome to Apple Swift version 4.2.1 (swiftlang-1000.11.42 clang-1000.11.45.1). Type :help for assistance.
  1> import Foundation 
  2. let a = Float80(6.8523015e+5) 
  3. let b = 6.8523015e+5 as Float80 
  4. print(a) 
  5. print(b) 
  6. print(a == b)
685230.1500000000233
685230.15
false
a: Float80 = 685230.150000000023283
b: Float80 = 685230.149999999999977
  7> ^D
$ xcrun --toolchain org.swift.5020190104a swift
swift_oss_helper command enabled.
Welcome to Apple Swift version 5.0-dev (LLVM c351ac7354, Clang 2b49a6d7dc, Swift 559f45ee8e).
Type :help for assistance.
  1> import Foundation 
  2. let a = Float80(6.8523015e+5) 
  3. let b = 6.8523015e+5 as Float80 
  4. print(a) 
  5. print(b) 
  6. print(a == b)
685230.15
685230.15
true
a: Float80 = 685230.149999999999977
b: Float80 = 685230.149999999999977