Fix generic mul accidental type promotion Int32 -> Int64 (JuliaLang#3…

…5164)
tekverkp · Mar 24, 2020 · 3df8899 · 3df8899
1 parent 9f08f88
commit 3df8899
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Showing 2 changed files with 11 additions and 4 deletions.
diff --git a/stdlib/LinearAlgebra/src/matmul.jl b/stdlib/LinearAlgebra/src/matmul.jl
@@ -649,7 +649,7 @@ function generic_matvecmul!(C::AbstractVector{R}, tA, A::AbstractVecOrMat, B::Ab
  for k = 1:mA
  aoffs = (k-1)*Astride
  if mB == 0
- s = zero(R)
+ s = false
  else
  s = zero(A[aoffs + 1]*B[1] + A[aoffs + 1]*B[1])
  end
@@ -662,7 +662,7 @@ function generic_matvecmul!(C::AbstractVector{R}, tA, A::AbstractVecOrMat, B::Ab
  for k = 1:mA
  aoffs = (k-1)*Astride
  if mB == 0
- s = zero(R)
+ s = false
  else
  s = zero(A[aoffs + 1]*B[1] + A[aoffs + 1]*B[1])
  end
@@ -676,14 +676,14 @@ function generic_matvecmul!(C::AbstractVector{R}, tA, A::AbstractVecOrMat, B::Ab
  if !iszero(_add.beta)
  C[i] *= _add.beta
  elseif mB == 0
- C[i] = zero(R)
+ C[i] = false
  else
  C[i] = zero(A[i]*B[1] + A[i]*B[1])
  end
  end
  for k = 1:mB
  aoffs = (k-1)*Astride
- b = _add(B[k], 0)
+ b = _add(B[k], false)
  for i = 1:mA
  C[i] += A[aoffs + i] * b
  end

diff --git a/stdlib/LinearAlgebra/test/matmul.jl b/stdlib/LinearAlgebra/test/matmul.jl
@@ -394,6 +394,13 @@ end
  end
 end
 
+@testset "#35163" begin
+ # typemax(Int32) * Int32(1) + Int32(1) * Int32(1) should wrap around
+ # not promote to Int64, convert to Int32 and throw inexacterror
+ val = mul!(Int32[1], fill(typemax(Int32), 1, 1), Int32[1], Int32(1), Int32(1))
+ @test val[1] == typemin(Int32)
+end
+
 # Number types that lack conversion to the destination type
 struct RootInt
  i::Int