Define conj and conj! for for Symmetric and Hermitian. (#17827)

Fixes #17780

Author: andreasnoack

base/linalg/symmetric.jl

@@ -114,6 +114,9 @@ end
 ctranspose(A::Hermitian) = A
 trace(A::Hermitian) = real(trace(A.data))
 
+Base.conj(A::HermOrSym) = typeof(A)(conj(A.data), A.uplo)
+Base.conj!(A::HermOrSym) = typeof(A)(conj!(A.data), A.uplo)
+
 #tril/triu
 function tril(A::Hermitian, k::Integer=0)
     if A.uplo == 'U' && k <= 0

test/linalg/symmetric.jl

@@ -236,3 +236,17 @@ let A = Symmetric(randn(5,5))
     B = -A
     @test A + B ≈ zeros(5,5)
 end
+
+# 17780
+let a = randn(2,2)
+    a = a'a
+    b = complex(a,a)
+    c = Symmetric(b)
+    @test conj(c) == conj(Array(c))
+    cc = copy(c)
+    @test conj!(c) == conj(Array(cc))
+    c = Hermitian(b + b')
+    @test conj(c) == conj(Array(c))
+    cc = copy(c)
+    @test conj!(c) == conj(Array(c))
+end