bug(cmake): makeHeader target references deleted file src/misc/makeHeader.cpp - breaks musl/Alpine builds

[satwareAG-ironMike]

Problem

Firebird v5.0.4 src/CMakeLists.txt:997 contains:

add_executable(makeHeader misc/makeHeader.cpp)

But src/misc/makeHeader.cpp was deleted in commit 45d5e3aa7a ("Refactor public include files (#205)"). The add_executable call was not removed, leaving a dangling reference to a non-existent source file.

On glibc systems (Debian, Fedora, AlmaLinux), CMake apparently tolerates this (the makeHeader target is behind if (NOT CMAKE_CROSSCOMPILING) and may never be evaluated). On musl libc (Alpine Linux), CMake validates source file existence at configure time and fails with:

CMake Error at src/CMakeLists.txt:997 (add_executable):
  No SOURCES given to target: makeHeader

CMake Generate step failed. Build files cannot be regenerated correctly.

Reproduction

docker run --rm alpine:3.21 sh -c '
  apk add --no-cache cmake ninja build-base git
  git clone --depth 1 --branch v5.0.4 https://github.com/FirebirdSQL/firebird.git /fbsrc
  mkdir -p /fbsrc/build && cd /fbsrc/build
  cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release
'
# Fails: No SOURCES given to target: makeHeader

Root Cause

Commit 45d5e3aa7a refactored public include file generation and deleted src/misc/makeHeader.cpp (83 lines removed) but did not remove the corresponding add_executable and set_output_directory calls in src/CMakeLists.txt:997-998.

The makeHeader binary was a helper that generated ibase.h from public headers (ibase.h, types_pub.h, consts_pub.h, etc.) by concatenating them. Post-refactor, ibase.h is generated or managed differently, making this target dead code.

Proposed Fix

Option A (minimal): Guard with file existence check:

if (NOT CMAKE_CROSSCOMPILING)
    if (EXISTS ${CMAKE_SOURCE_DIR}/src/misc/makeHeader.cpp)
        add_executable          (makeHeader misc/makeHeader.cpp)
        set_output_directory    (makeHeader . CURRENT_DIR)
        # ... rest of makeHeader block ...
    endif()
endif()

Option B (clean): Remove the entire makeHeader block (lines 997-1018) since the source file was deleted and the functionality was refactored away. The add_custom_command at line 1016 that calls makeHeader should also be removed.

Impact

• Alpine Linux / musl libc: Cannot build Firebird client library from source
• php-firebird: APK packaging blocked (issue satwareAG/php-firebird Locally exploitable stack overflow [CORE167] #496)
• Downstream: Any distribution using musl libc cannot build Firebird from source

Environment

• Firebird: v5.0.4 (latest stable, released 2026-04-17)
• CMake: 3.31.1 (Alpine 3.21)
• OS: Alpine Linux 3.21 (musl libc 1.2.5)
• GCC: 14.2.0

Context

This was discovered during CI validation of php-firebird's Alpine APK packaging (packaging/apk/APKBUILD), which builds libfbclient from source for musl libc. The official FB5 client tarball is glibc-linked and cannot be used on Alpine without building from source.

The makeHeader target is behind if (NOT CMAKE_CROSSCOMPILING) — on glibc systems, CMake appears to skip evaluation of source existence for targets that are never built. On musl, CMake validates all add_executable calls at configure time regardless of whether the target will be built.