BUG: amos/amos.h: fix scope of l in seri (#92)

* BUG: amos/amos.h: fix scope of l in seri

Fix the scope of l such that its value from the loop is conserved after
the goto statement in the loop's body.

* TST: add test for gh-92

* TST: add test for #92

* revert fix

* Update tests/xsf_tests/test_amos.cpp

Co-authored-by: Florian Bourgey <bourgeyflorian@gmail.com>

* revert 'revert fix'

---------

Co-authored-by: Florian Bourgey <bourgeyflorian@gmail.com>

Author: JaRoSchm

include/xsf/amos/amos.h

@@ -4476,8 +4476,8 @@ namespace amos {
             //
             s1 = w[0];
             s2 = w[1];
-            l = 3;
-            for (int l = 3; l < (nn + 1); l++) {
+            int l;
+            for (l = 3; l < (nn + 1); l++) {
                 ck = s2;
                 s2 = s1 + (ak + fnu) * rz * s2;
                 s1 = ck;

tests/xsf_tests/test_amos.cpp

@@ -62,6 +62,28 @@ TEST_CASE("amos besi vectorized", "[amos][xsf_tests]") {
     }
 }
 
+TEST_CASE("amos seri buffer overflow gh-92", "[amos][xsf_tests]") {
+    using std::complex;
+
+    // parameters for besh which trigger overflow in seri
+    const complex<double> z{14.0, -3.0};
+    const double fnu = 1.0;
+    const int m = 1;
+    const int n = 260;
+    const int kode = 1;
+
+    const complex<double> sentinel{12345.67, 98765.43};
+    std::vector<complex<double>> cy(n + 2, sentinel);
+
+    int ierr = 0;
+    int nz = xsf::amos::besh(z, fnu, kode, m, n, cy.data() + 1, &ierr);
+
+    // check if guards elements were touched
+    CAPTURE(cy[0], cy[n + 1]);
+    CHECK(cy[0] == sentinel);
+    CHECK(cy[n + 1] == sentinel);
+}
+
 TEST_CASE("amos asyi buffer overflow gh-158", "[amos][xsf_tests]") {
     using std::complex;