Avoid warning with empty upper triangular solves

JuliaLinearAlgebra · Jun 3, 2024 · 8c62e0e · 8c62e0e
1 parent 8618b18
commit 8c62e0e
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Showing 3 changed files with 13 additions and 6 deletions.
diff --git a/Project.toml b/Project.toml
@@ -1,6 +1,6 @@
 name = "BandedMatrices"
 uuid = "aae01518-5342-5314-be14-df237901396f"
-version = "1.7"
+version = "1.7.1"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

diff --git a/src/blas.jl b/src/blas.jl
@@ -130,11 +130,13 @@ for (fname, elty) in ((:dtbsv_,:Float64),
                 throw(DimensionMismatch("size of A is $n != length(x) = $(length(x))"))
             end
             chkstride1(A)
-            ccall((@blasfunc($fname), libblas), Cvoid,
-                (Ref{UInt8}, Ref{UInt8}, Ref{UInt8}, Ref{BlasInt}, Ref{BlasInt},
-                 Ptr{$elty}, Ref{BlasInt}, Ptr{$elty}, Ref{BlasInt}),
-                 uplo, trans, diag, m, k,
-                 A, max(1,stride(A,2)), x, stride(x, 1))
+            if n ≠ 0 # avoid empty warning message
+                ccall((@blasfunc($fname), libblas), Cvoid,
+                    (Ref{UInt8}, Ref{UInt8}, Ref{UInt8}, Ref{BlasInt}, Ref{BlasInt},
+                    Ptr{$elty}, Ref{BlasInt}, Ptr{$elty}, Ref{BlasInt}),
+                    uplo, trans, diag, m, k,
+                    A, max(1,stride(A,2)), x, stride(x, 1))
+            end
             x
         end
         function tbsv(uplo::AbstractChar, trans::AbstractChar, diag::AbstractChar,

diff --git a/test/test_tribanded.jl b/test/test_tribanded.jl
@@ -114,6 +114,11 @@ import BandedMatrices: BandedColumns, BandedRows, isbanded
         @test rot180(LowerTriangular(B)) == rot180(Matrix(LowerTriangular(B)))
         @test rot180(UnitLowerTriangular(B)) == rot180(Matrix(UnitLowerTriangular(B)))
     end
+
+    @testset "empty uppertriangular" begin
+        B = brand(0,0,2,1)
+        @test UpperTriangular(B) \ Float64[] == Float64[]
+    end
 end
 
 end # module