Failure to check dimensions when multiplying an empty array

[timholy]

Using 1.12.0-DEV.1738 (2024-12-10)

julia> using LinearAlgebra

julia> A = rand(0, 0); B = rand(1, 5);

julia> A*B
0×5 Matrix{Float64}

julia> A = rand(0, 1); B = rand(2, 5);

julia> A*B
0×5 Matrix{Float64}

julia> A = rand(1, 1); B = rand(2, 5);

julia> A*B
ERROR: DimensionMismatch: A has dimensions (1,1) but B has dimensions (2,5)
Stacktrace:
 [1] gemm_wrapper!
   @ ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:752 [inlined]
 [2] _syrk_herk_gemm_wrapper!
   @ ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:470 [inlined]
 [3] generic_matmatmul_wrapper!(C::Matrix{…}, tA::Char, tB::Char, A::Matrix{…}, B::Matrix{…}, α::Bool, β::Bool, val::Val{…})
   @ LinearAlgebra ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:450
 [4] _mul!
   @ ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:326 [inlined]
 [5] mul!
   @ ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:295 [inlined]
 [6] mul!
   @ ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:263 [inlined]
 [7] *(A::Matrix{Float64}, B::Matrix{Float64})
   @ LinearAlgebra ~/src/juliaw/usr/share/julia/stdlib/v1.12/LinearAlgebra/src/matmul.jl:134
 [8] top-level scope
   @ REPL[7]:1
Some type information was truncated. Use `show(err)` to see complete types.

The last case is correct, the others should also throw a DimensionMismatch.

Noticed in JuliaStats/PDMats.jl#212