fix: free tau_Re_vf in all viscous runs, not only cyl_coord

[sbryngelson]

Summary

Fixes #1366.

In s_finalize_rhs_module, tau_Re_vf is allocated inside if (viscous) but was only deallocated inside if (cyl_coord). Any Cartesian viscous run (viscous = .true., cyl_coord = .false.) leaked all tau_Re_vf host and GPU allocations.

The fix removes the erroneous if (cyl_coord) guard — the deallocation is already inside the if (viscous) block, so no additional condition is needed.

Change

src/simulation/m_rhs.fpp: drop the if (cyl_coord) then ... end if wrapper around the three tau_re_vf @:DEALLOCATE calls.

Test plan

• Existing viscous regression tests pass
• Existing cylindrical-coordinate viscous tests pass (deallocation still fires via the outer if (viscous) guard)

[github-actions]

Claude Code Review

Head SHA: dcb8a72

Files changed:

• 1
• src/simulation/m_rhs.fpp

Findings

Memory management: @:DEALLOCATE guard removed without confirming @:ALLOCATE is unconditional

src/simulation/m_rhs.fpp — deallocation hunk

The if (cyl_coord) guard is removed from three @:DEALLOCATE calls for tau_re_vf:

-                if (cyl_coord) then
-                    do i = 1, num_dims
-                        @:DEALLOCATE(tau_re_vf(eqn_idx%cont%end + i)%sf)
-                    end do
-                    @:DEALLOCATE(tau_re_vf(eqn_idx%E)%sf)
-                    @:DEALLOCATE(tau_re_vf)
-                end if
+                do i = 1, num_dims
+                    @:DEALLOCATE(tau_re_vf(eqn_idx%cont%end + i)%sf)
+                end do
+                @:DEALLOCATE(tau_re_vf(eqn_idx%E)%sf)
+                @:DEALLOCATE(tau_re_vf)

Per CLAUDE.md: "Conditional allocation MUST have conditional deallocation."

The matching @:ALLOCATE calls for tau_re_vf and its .sf components are not shown in this diff. If those allocations are still guarded by if (cyl_coord), then attempting to deallocate these arrays when cyl_coord = .false. will cause a Fortran runtime error (deallocation of an unallocated variable). The change is safe only if the allocation side is also unconditional. Please verify that the @:ALLOCATE calls for tau_re_vf and tau_re_vf(...)%sf are unconditional (or have been made unconditional as part of this fix).

[sbryngelson]

The fix is correct. The allocation of tau_Re_vf at line 333 of m_rhs.fpp is guarded only by if (viscous) — there is no cyl_coord guard anywhere near the allocation:

if (viscous) then
    @:ALLOCATE(tau_Re_vf(1:sys_size))
    do i = 1, num_dims
        @:ALLOCATE(tau_Re_vf(eqn_idx%cont%end + i)%sf(...))
    end do
    @:ALLOCATE(tau_Re_vf(eqn_idx%E)%sf(...))
    ...
end if

The old code had the deallocation incorrectly nested inside if (cyl_coord), which had no corresponding guard on the allocation — that asymmetry was the original bug causing a memory leak in Cartesian (cyl_coord = .false.) viscous runs. The fix removes the spurious cyl_coord guard from the deallocation so both allocation and deallocation are symmetric: they both execute whenever viscous = .true., regardless of cyl_coord.

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ℹ️ Review info

⚙️ Run configuration

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Review profile: CHILL

Plan: Pro

Run ID: 7e3d0271-b83a-4878-ad67-c4bb98b2a5ae

📥 Commits

Reviewing files that changed from the base of the PR and between d513442 and dcb8a72.

📒 Files selected for processing (1)

• src/simulation/m_rhs.fpp

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[sbryngelson]

Automated Code Review

Summary: No issues found. ✅

Verified:

• All three tau_Re_vf allocation levels are now symmetrically paired with their deallocations after removing the if (cyl_coord) guard
• GPU deallocation is fully covered — @:DEALLOCATE macro always emits GPU_EXIT_DATA(delete=...) before the Fortran deallocate
• No double-free risk: tau_Re_vf is allocated in exactly one place (inside if (viscous)) and deallocated in one matching block
• The igr path is consistent: both allocation (if (.not. igr)) and deallocation (if (.not. igr)) carry the same guard — igr=true runs unaffected

Minimal, correct fix. Safe to merge.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.77%. Comparing base (d513442) to head (dcb8a72).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1398      +/-   ##
==========================================
+ Coverage   64.75%   64.77%   +0.01%     
==========================================
  Files          71       71              
  Lines       18721    18717       -4     
  Branches     1551     1550       -1     
==========================================
  Hits        12123    12123              
+ Misses       5640     5637       -3     
+ Partials      958      957       -1     

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