Reuse in diagonal and bidiag

Author: jishnub

src/matmul.jl

@@ -408,15 +408,24 @@ julia> lmul!(F.Q, B)
 """
 lmul!(A, B)
 
-_vec_or_mat_str(s::Tuple{Any}) = :vector
-_vec_or_mat_str(s::Tuple{Any,Any}) = :matrix
+_vec_or_mat_str(s::Tuple{Any}) = "vector"
+_vec_or_mat_str(s::Tuple{Any,Any}) = "matrix"
 @noinline function matmul_size_check(sizeA::Tuple{Integer,Vararg{Integer}}, sizeB::Tuple{Integer,Vararg{Integer}})
     strA = _vec_or_mat_str(sizeA)
     strB = _vec_or_mat_str(sizeB)
     szA2 = get(sizeA, 2, 1)
+    B_size_len = length(sizeB) == 1 ? sizeB[1] : sizeB
+    size_or_len_str_B = B_size_len isa Integer ? "length" : "size"
+    dim_or_len_str_B = B_size_len isa Integer ? "length" : "first dimension"
+    pos_str_A = (length(sizeA) == length(sizeB) ? "first " : "")*strA
+    pos_str_B = (length(sizeA) == length(sizeB) ? "second " : "")*strB
     if szA2 != sizeB[1]
         throw(DimensionMismatch(
-            lazy"incompatible dimensions for matrix multiplication: tried to multiply a $strA of size $sizeA with a $strB of size $sizeB.",
+            LazyString(
+                lazy"incompatible dimensions for matrix multiplication: ",
+                lazy"tried to multiply a $strA of size $sizeA with a $strB of $size_or_len_str_B $B_size_len. ",
+                lazy"The second dimension of the $pos_str_A: $szA2, does not match the $dim_or_len_str_B of the $pos_str_B: $(sizeB[1])."
+            )
             )
         )
     end
@@ -425,16 +434,22 @@ end
 @noinline function matmul_size_check(sizeC::Tuple{Integer,Vararg{Integer}}, sizeA::Tuple{Integer,Vararg{Integer}}, sizeB::Tuple{Integer,Vararg{Integer}})
     strA = _vec_or_mat_str(sizeA)
     strB = _vec_or_mat_str(sizeB)
+    strC = _vec_or_mat_str(sizeC)
     szB2 = get(sizeB, 2, 1)
     szC2 = get(sizeC, 2, 1)
     matmul_size_check(sizeA, sizeB)
     if sizeC[1] != sizeA[1] || szC2 != szB2
-        destsize = length(sizeB) == length(sizeC) == 1 ? (sizeA[1],) : (sizeA[1], szB2)
+        C_size_len = length(sizeC) == 1 ? sizeC[1] : sizeC
+        size_or_len_str_C = C_size_len isa Integer ? "length" : "size"
+        B_size_len = length(sizeB) == 1 ? sizeB[1] : sizeB
+        size_or_len_str_B = B_size_len isa Integer ? "length" : "size"
+        destsize = length(sizeB) == length(sizeC) == 1 ? sizeA[1] : (sizeA[1], szB2)
+        size_or_len_str_dest = destsize isa Integer ? "length" : "size"
         throw(DimensionMismatch(
                 LazyString(
                 "incompatible destination size: ",
-                lazy"the destination of size $sizeC is incomatible with the multiplication of a $strA of size $(sizeA) and a $strB of size $(sizeB). ",
-                lazy"The destination must be of size $destsize."
+                lazy"the destination $strC of $size_or_len_str_C $C_size_len is incomatible with the product of a $strA of size $sizeA and a $strB of $size_or_len_str_B $B_size_len. ",
+                lazy"The destination must be of $size_or_len_str_dest $destsize."
                )
             )
         )