From 9d925f81c9accaac7ab6c1f7c51983d535b1b0d0 Mon Sep 17 00:00:00 2001
From: Jatin Agarwal <167195254+Jatinagarwal24@users.noreply.github.com>
Date: Fri, 10 Apr 2026 23:36:29 +0530
Subject: [PATCH] fix: allocate lam_tmp before passing to
 solve_dirac_eigenproblem
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The crash was caused by passing an unallocated array (lam_tmp) to
solve_dirac_eigenproblem in src/schroed_dirac_solver.f90 (around line 155).

LFortran correctly detects this and raises a runtime error:
“argument is unallocated”.

This fix ensures lam_tmp is properly allocated before the call,
preventing the runtime failure. The issue is in featom code and is
not a bug in LFortran.
---
 src/schroed_dirac_solver.f90 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/schroed_dirac_solver.f90 b/src/schroed_dirac_solver.f90
index 376a4ef..00b8256 100644
--- a/src/schroed_dirac_solver.f90
+++ b/src/schroed_dirac_solver.f90
@@ -64,6 +64,7 @@ subroutine total_energy(Z, rmax, Ne, a, p, Nq, DOFs, alpha_int, dirac_int, &
 
     allocate(H(DOFS, DOFS), S(DOFS), DSQ(DOFS), uq(Nq,Ne))
     allocate(D(DOFS, DOFS), lam2(DOFS), rho(Nq,Ne), fullc(Nn))
+    allocate(lam_tmp(DOFS))
     if (dirac_int == 1) then
         allocate(lam(47))
         allocate(eigfn(Nq, Ne, 49))