• Alberto Donizetti's avatar
    cmd/compile: diagnose constant division by complex zero · 10a200e5
    Alberto Donizetti authored
    When casting an ideal to complex{64,128}, for example during the
    evaluation of
    
      var a = complex64(0) / 1e-50
    
    we want the compiler to report a division-by-zero error if a divisor
    would be zero after the cast.
    
    We already do this for floats; for example
    
      var b = float32(0) / 1e-50
    
    generates a 'division by zero' error at compile time (because
    float32(1e-50) is zero, and the cast is done before performing the
    division).
    
    There's no such check in the path for complex{64,128} expressions, and
    no cast is performed before the division in the evaluation of
    
      var a = complex64(0) / 1e-50
    
    which compiles just fine.
    
    This patch changes the convlit1 function so that complex ideals
    components (real and imag) are correctly truncated to float{32,64}
    when doing an ideal -> complex{64, 128} cast.
    
    Fixes #11674
    
    Change-Id: Ic5f8ee3c8cfe4c3bb0621481792c96511723d151
    Reviewed-on: https://go-review.googlesource.com/37891
    Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
    TryBot-Result: Gobot Gobot <gobot@golang.org>
    Reviewed-by: 's avatarRobert Griesemer <gri@golang.org>
    10a200e5
mpfloat.go 5.09 KB