<div class="highlight highlight-source-julia notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="Base.:+(x::Int, y::Int) = println(x, y)
# 'julia' terminated by signal SIGSEGV (Address boundary error)

Base.:+(x::Int, y::Int) = 1
# KeyError: key :normal not found in getindex(::Dict{Any,Any}, ::Symbol) at ./dict.jl:478

Base.:+(x::Int, y) = 1
# fatal: error thrown and no exception handler available:
# MethodError(f=typeof(Base.:(+))(), args=(55, 1), world=0x00000000000069e3)

Base.:+(x, y::Int) = 1
# As above, but sometimes &quot;signal (4): Illegal instruction: 4&quot; instead

Base.:+(x, y) = 1 # this works!"><pre class="notranslate">Base.:<span class="pl-k">+</span>(x<span class="pl-k">::</span><span class="pl-c1">Int</span>, y<span class="pl-k">::</span><span class="pl-c1">Int</span>) <span class="pl-k">=</span> <span class="pl-c1">println</span>(x, y)
<span class="pl-c"><span class="pl-c">#</span> 'julia' terminated by signal SIGSEGV (Address boundary error)</span>

Base.:<span class="pl-k">+</span>(x<span class="pl-k">::</span><span class="pl-c1">Int</span>, y<span class="pl-k">::</span><span class="pl-c1">Int</span>) <span class="pl-k">=</span> <span class="pl-c1">1</span>
<span class="pl-c"><span class="pl-c">#</span> KeyError: key :normal not found in getindex(::Dict{Any,Any}, ::Symbol) at ./dict.jl:478</span>

Base.:<span class="pl-k">+</span>(x<span class="pl-k">::</span><span class="pl-c1">Int</span>, y) <span class="pl-k">=</span> <span class="pl-c1">1</span>
<span class="pl-c"><span class="pl-c">#</span> fatal: error thrown and no exception handler available:</span>
<span class="pl-c"><span class="pl-c">#</span> MethodError(f=typeof(Base.:(+))(), args=(55, 1), world=0x00000000000069e3)</span>

Base.:<span class="pl-k">+</span>(x, y<span class="pl-k">::</span><span class="pl-c1">Int</span>) <span class="pl-k">=</span> <span class="pl-c1">1</span>
<span class="pl-c"><span class="pl-c">#</span> As above, but sometimes "signal (4): Illegal instruction: 4" instead</span>

Base.:<span class="pl-k">+</span>(x, y) <span class="pl-k">=</span> <span class="pl-c1">1</span> <span class="pl-c"><span class="pl-c">#</span> this works!</span></pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="julia&gt; versioninfo()
Julia Version 0.7.0-DEV.4564
Commit 46dcb35e1b (2018-03-12 15:00 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin16.7.0)
  CPU: Intel(R) Core(TM) i7-3615QM CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, ivybridge)
Environment:
  JULIA_EDITOR = subl"><pre class="notranslate"><code class="notranslate">julia&gt; versioninfo()
Julia Version 0.7.0-DEV.4564
Commit 46dcb35e1b (2018-03-12 15:00 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin16.7.0)
  CPU: Intel(R) Core(TM) i7-3615QM CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, ivybridge)
Environment:
  JULIA_EDITOR = subl
</code></pre></div>
<p dir="auto">This may be a dumb thing to do, but probably it shouldn't segfault:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="julia&gt; import Base.*; *(::Int, ::Int) = 3
Segmentation fault: 11"><pre class="notranslate"><code class="notranslate">julia&gt; import Base.*; *(::Int, ::Int) = 3
Segmentation fault: 11
</code></pre></div>
<p dir="auto">This issue does not occur in 0.5.1.</p>
<p dir="auto">Version info:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Julia Version 0.6.0-pre.alpha.58
Commit 015cc63 (2017-03-06 15:15 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin16.4.0)
  CPU: Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, haswell)"><pre class="notranslate"><code class="notranslate">Julia Version 0.6.0-pre.alpha.58
Commit 015cc63 (2017-03-06 15:15 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin16.4.0)
  CPU: Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: libopenblas64_
  LIBM: libopenlibm
  LLVM: libLLVM-3.9.1 (ORCJIT, haswell)
</code></pre></div>