Fix CMake package config generation with CMAKE_INSTALL_MODE=SYMLINK

[PeterCDMcLean]

When CMAKE_INSTALL_MODE=SYMLINK is used, CMake creates symlinks instead of copying files during install. The package config file generation was using REALPATH which follows symlinks to the actual file, breaking the relative path computation.

Changed from REALPATH to ABSOLUTE so that symlink paths are preserved, allowing the relative path calculation to work correctly with both copy and symlink install modes.

This fixes build failures for packages like hipBLASLt and rocRoller when using CMAKE_INSTALL_MODE=SYMLINK.

Motivation

Technical Details

Test Plan

Test Result

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[PeterCDMcLean]

REALPATH vs ABSOLUTE Explanation

The issue is in how CMake resolves file paths when dealing with symlinks:

REALPATH

• Follows all symlinks to their ultimate target
• Resolves to the actual physical file on disk
• Example:
  Symlink: /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common/hipblas-common-config.cmake
  ↓ (points to)
  Real file: /workspace/build/math-libs/BLAS/hipBLAS-common/build/hipblas-common-config.cmake

REALPATH returns: /workspace/build/math-libs/BLAS/hipBLAS-common/build/hipblas-common-config.cmake

ABSOLUTE

• Canonicalizes the path (removes . and ..)
• Does NOT follow symlinks - uses the symlink path itself
• Example:
  Symlink: /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common/hipblas-common-config.cmake

ABSOLUTE returns: /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common/hipblas-common-config.cmake

The Problem

When CMAKE_INSTALL_MODE=SYMLINK, CMake creates symlinks instead of copying files during install:

1. Config location (symlink): /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common/hipblas-common-config.cmake
2. Symlink target (real file): ../../../../build/hipblas-common-config.cmake

The config file code tries to compute PACKAGE_PREFIX_DIR by going up 3 directories:

With REALPATH (BROKEN):
get_filename_component(_ROCM_CMAKE_CURRENT_LIST_FILE_REAL "${CMAKE_CURRENT_LIST_FILE}" REALPATH)

Returns: /workspace/build/math-libs/BLAS/hipBLAS-common/build/hipblas-common-config.cmake

get_filename_component(_ROCM_CMAKE_CURRENT_LIST_DIR_REAL "${_ROCM_CMAKE_CURRENT_LIST_FILE_REAL}" DIRECTORY)

Returns: /workspace/build/math-libs/BLAS/hipBLAS-common/build

get_filename_component(PACKAGE_PREFIX_DIR "${_ROCM_CMAKE_CURRENT_LIST_DIR_REAL}/../../../" ABSOLUTE)

Goes up 3 from build/: ../../../ = /workspace/build/math-libs ❌ WRONG!

With ABSOLUTE (CORRECT):
get_filename_component(_ROCM_CMAKE_CURRENT_LIST_FILE_ABS "${CMAKE_CURRENT_LIST_FILE}" ABSOLUTE)

Returns: /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common/hipblas-common-config.cmake

get_filename_component(_ROCM_CMAKE_CURRENT_LIST_DIR_ABS "${_ROCM_CMAKE_CURRENT_LIST_FILE_ABS}" DIRECTORY)

Returns: /workspace/build/math-libs/BLAS/hipBLAS-common/dist/lib/cmake/hipblas-common

get_filename_component(PACKAGE_PREFIX_DIR "${_ROCM_CMAKE_CURRENT_LIST_DIR_ABS}/../../../" ABSOLUTE)

Goes up 3 from dist/lib/cmake/hipblas-common: ../../../ = /workspace/build/math-libs/BLAS/hipBLAS-common/dist ✅ CORRECT!

The fix changes line 73 in ROCMPackageConfigHelpers.cmake from REALPATH to ABSOLUTE so it respects symlink install mode. This makes package config files work correctly whether files are copied or symlinked.

[PeterCDMcLean]

I'm very happy that there are tests that caught this. Trying to understand the context of the failure. Looks like my change doesn't work with PREFIX:

Root Cause Analysis

The ABSOLUTE fix (changing from REALPATH to ABSOLUTE on line 73) works correctly for standard installations and CMAKE_INSTALL_MODE=SYMLINK, but breaks when using ROCM_PREFIX with rocm_install_symlink_subdir(). Here's why:

Path Depth Mismatch

When PREFIX=simple is set, the installation structure is:

Real files:

• Config: /usr/simple/lib/cmake/simple/simple-config.cmake (4 levels deep from /usr)
• Include: /usr/simple/include/simple.h

Symlinks created by rocm_install_symlink_subdir():

• Config: /usr/lib/cmake/simple/simple-config.cmake → ../../../simple/lib/cmake/simple/simple-config.cmake (3 levels deep from /usr)
• Include: /usr/include/simple.h → ../simple/include/simple.h

The PACKAGE_RELATIVE_PATH Calculation

In rocm_export_targets() with PREFIX:
CONFIG_PACKAGE_INSTALL_DIR = simple/lib/cmake/simple # 4 components

In rocm_configure_package_config_file():
ABSOLUTE_INSTALL_DIR = /usr/simple/lib/cmake/simple
INSTALL_PREFIX = /usr
PACKAGE_RELATIVE_PATH = ../../../../ # 4 levels up

This is correct for the real file location.

What Happens with REALPATH (original code)

  # Config found at: /usr/lib/cmake/simple/simple-config.cmake (symlink)
  get_filename_component(...REALPATH)
  # Follows symlink to: /usr/simple/lib/cmake/simple/simple-config.cmake
  # Directory: /usr/simple/lib/cmake/simple
  # Up 4 levels: /usr ✓ CORRECT

What Happens with ABSOLUTE (the fix)

  # Config found at: /usr/lib/cmake/simple/simple-config.cmake (symlink)
  get_filename_component(...ABSOLUTE)
  # Stays at: /usr/lib/cmake/simple/simple-config.cmake (doesn't follow symlink)
  # Directory: /usr/lib/cmake/simple
  # Up 4 levels: /../ ✗ ONE LEVEL TOO HIGH!

The error message confirms this:
Expected: .../pass-simple-prefix-EkB98/usr/simple/include
Actual: .../pass-simple-prefix-EkB98/simple/include # missing /usr/

Why This Happens

The PACKAGE_RELATIVE_PATH is always computed based on the real installation depth (4 levels when PREFIX adds an extra component), but with ABSOLUTE:

• Real path depth: /usr/simple/lib/cmake/simple = 4 levels from prefix
• Symlink path depth: /usr/lib/cmake/simple = 3 levels from prefix (PREFIX component removed)

Going up 4 levels from a 3-level-deep symlink overshoots by one directory level.

Solution Approaches

The fix would need to handle this mismatch. Possible approaches:

1. Detect symlink usage: Check if we're at a symlink and adjust the relative path count
2. Use PREFIX-aware relative paths: When PREFIX is used with symlinks, compute a separate PACKAGE_RELATIVE_PATH for the symlink location
3. Fix CHECK_PREFIX logic: The existing CHECK_PREFIX code (lines 39-50 in ROCMPackageConfigHelpers.cmake) tries to handle PREFIX but only for Windows - extend this to handle Unix symlinks
4. Change symlink strategy: Instead of flattening the PREFIX in symlinks, preserve the directory structure (but this would change the installation layout)

The ABSOLUTE fix is correct for the use case it was designed for (CMAKE_INSTALL_MODE=SYMLINK without PREFIX), but inadvertently breaks the PREFIX+symlink combination because of this path depth assumption mismatch.