TST: fix lqmn test build failure on windows

Author: jorenham

tests/scipy_special_tests/test_lqmn.cpp

@@ -13,14 +13,12 @@ TEST_CASE("lqmn TestLegendreFunctions.test_lqmn", "[lqmn][lqn][real][smoketest]"
     constexpr int m = 0;
     constexpr int n = 2;
     constexpr double x = 0.5;
-
-    constexpr int m1p = m + 1;
-    constexpr int n1p = n + 1;
-    // lqmn requires buffer space for at least 2x2
-    constexpr int bufsize = std::max(2, m1p) * std::max(2, n1p);
+    // `xsf::lqmn` requires the matrices to be at least 2x2
+    constexpr int m1p = std::max(2, m + 1);
+    constexpr int n1p = std::max(2, n + 1);
 
     // lqmnf = special.lqmn(0, 2, .5)
-    double lqmnf0_data[bufsize], lqmnf1_data[bufsize];
+    double lqmnf0_data[m1p * n1p], lqmnf1_data[m1p * n1p];
     auto lqmnf0 = std::mdspan(lqmnf0_data, m1p, n1p);
     auto lqmnf1 = std::mdspan(lqmnf1_data, m1p, n1p);
     xsf::lqmn(x, lqmnf0, lqmnf1);
@@ -95,21 +93,25 @@ TEST_CASE("lqmn TestLegendreFunctions.test_lqmn_gt1", "[lqmn][real][smoketest]")
 TEST_CASE("lqmn complex", "[lqmn][complex][smoketest]") {
     constexpr double atol = 1e-16;
     constexpr double x = 0.5;
-    // lqmn requires buffer space for at least 2x2
-    constexpr int bufsize = 2 * 2;
+
+    constexpr int m = 0;
+    constexpr int n = 0;
+    // `xsf::lqmn` requires the matrices to be at least 2x2
+    constexpr int m1p = std::max(2, m + 1);
+    constexpr int n1p = std::max(2, n + 1);
 
     // (q_mn, qp_mn) = lqmn(0, 0, 0.5)
-    double q_data[bufsize], qp_data[bufsize];
-    auto q_mn = std::mdspan(q_data, 1, 1);
-    auto qp_mn = std::mdspan(qp_data, 1, 1);
+    double q_data[m1p * n1p], qp_data[m1p * n1p];
+    auto q_mn = std::mdspan(q_data, m1p, n1p);
+    auto qp_mn = std::mdspan(qp_data, m1p, n1p);
     xsf::lqmn(x, q_mn, qp_mn);
     auto q = q_mn(0, 0);
     auto qp = qp_mn(0, 0);
 
     // (cq_mn, cqp_mn) = lqmn(0, 0, 0.5 + 0j)
-    std::complex<double> cq_data[bufsize], cqp_data[bufsize];
-    auto cq_mn = std::mdspan(cq_data, 1, 1);
-    auto cqp_mn = std::mdspan(cqp_data, 1, 1);
+    std::complex<double> cq_data[m1p * n1p], cqp_data[m1p * n1p];
+    auto cq_mn = std::mdspan(cq_data, m1p, n1p);
+    auto cqp_mn = std::mdspan(cqp_data, m1p, n1p);
     xsf::lqmn(std::complex<double>(x, 0.0), cq_mn, cqp_mn);
     auto cq = cq_mn(0, 0);
     auto cqp = cqp_mn(0, 0);