IFX 2026 debugger cannot display array variables in Visual Studio 2026

[MartiBayer]

Hi,

I recently migrated from Visual Studio 2019 Community to Visual Studio 2026 Professional and am now compiling with Intel® Fortran Compiler (IFX) 2026.0.0.

The code runs correctly, but I have a debugger issue.

Environment

• Visual Studio 2026 Professional (18.7.3)
• Intel Fortran Compiler 2026.0.0 (IFX)
• x64 Debug configuration
• Windows 11

Problem

In Visual Studio 2019 I could inspect array variables in the debugger and see all elements.

With IFX 2026, some arrays cannot be displayed in either the Watch or Locals windows.

Example:

SUBROUTINE SET_WELL_FILE_AND_RUNMODFLOW(...)

   IMPLICIT NONE

   INTEGER :: NSIMS,NREM_WELLS

  INTEGER :: REM_WELL_CELL(NSIMS,NREM_WELLS)

  REAL    :: REM_WELL_RATE(NSIMS,NREM_WELLS)

   ...

   CELL = REM_WELL_CELL(SIM,I)

  RATE = REM_WELL_RATE(SIM,I)

 END SUBROUTINE

When stopped at a breakpoint:

• Scalars are displayed correctly:

RATE

SIM

I

• However:

REM_WELL_CELL

REM_WELL_RATE

 

cannot be displayed.

In the Watch window I get:

identifier "REM_WELL_CELL" is undefined

identifier "REM_WELL_RATE" is undefined

In the Locals window I get:

An unspecified error has occurred.

Additional tests

I created a local fixed-size array:

REAL :: TEST(5)

TEST = (/1.0,2.0,3.0,4.0,5.0/)

The debugger displays TEST correctly.

I also created local copies:

INTEGER :: CELL_COPY(NSIMS,NREM_WELLS)

REAL    :: RATE_COPY(NSIMS,NREM_WELLS)

CELL_COPY = REM_WELL_CELL

RATE_COPY = REM_WELL_RATE

But the debugger still reports: An unspecified error has occurred.

for CELL_COPY and RATE_COPY.

Interestingly, the Locals window shows metadata such as:

CELL_COPY$1superbound

CELL_COPY$2superbound

REM_WELL_CELL$1superbound

REM_WELL_CELL$2superbound

so the debugger appears to know the array dimensions, but not the contents.

Question

Is this a known IFX 2026 debugger limitation/bug related to:

• adjustable arrays with runtime bounds?
• local automatic arrays?
• Visual Studio 2026 integration?

Has anyone found a workaround that allows array contents to be inspected in the debugger?

Thanks.

[henry_collins]

Yes, this looks like a known limitation or regression with IFX + VS 2026 debug visualization for assumed or automatic arrays. The fact that scalars show fine and the $superbound metadata appears means the debugger is seeing the symbol info, but failing to materialize the runtime buffer for dynamic-shaped locals.

A few people have hit this specifically with adjustable or automatic arrays especially in x64 Debug with IFX 2026.

Workarounds that usually help:

• Try compiling with -Od -g plus disabling optimization completely (IFX sometimes still “partially optimizes” array storage).

• Temporarily convert to explicit-shape allocatable arrays:

INTEGER, ALLOCATABLE :: REM_WELL_CELL(:,:)

• Or copy into a fixed-size debug buffer (what you already tried, but ensure it’s not optimized away, use VOLATILE on the source dest).
• In some cases, switching debug format to /debug:full  improves watch evaluation.

Also worth noting: VS Watch window often fails with IFX unless the array has fully resolvable bounds at compile time, so this may be more of a debug info + VS natvis gap than your code.

[DonRobinsonESSA]

This might be due to a problem with the Fortran Expression Evaluator. Check under the Extensions tab and see if this is extension installed. You may need to Uninstall then re-install. This resulted in much better resolution of variables for me and resolved many of the error messages you're seeing.