Fix #2598: don't propagate build commands from root buildType to deps

[queelius]

Summary

• Fixes preBuildCommands/postBuildCommands tainting _all_ dependencies from root package #2598: preBuildCommands/postBuildCommands (and all other command hooks) defined in a custom buildType in the root package were incorrectly executed for every dependency during the build.
• When addBuildTypeSettings is called for a non-root package, command fields and their associated environments are now cleared from the buildType settings before propagation, matching the existing pattern that already strips unittest options for dependencies.
• Added a unit test that verifies commands from a custom buildType are present for the root package but absent for dependencies.

Root cause

In Project.addBuildTypeSettings() (source/dub/project.d), the root package's buildType settings (including all command hooks) were applied to every target via processVars(). The for_root_package flag was only used to strip unittest options, but commands were never filtered.

Test plan

• New unit test in source/dub/test/others.d that creates a project with a custom buildType containing all 6 command types, a dependency, and verifies commands appear only for the root package
• Confirmed the test fails without the fix (1/56 modules FAILED) and passes with it (56 modules passed)
• All existing tests continue to pass

🤖 Generated with Claude Code

[github-actions]

✅ PR OK, no changes in deprecations or warnings

Total deprecations: 0

Total warnings: 0

Build statistics:

 statistics (-before, +after)
 executable size=5710288 bin/dub
-rough build time=66s
+rough build time=68s

Full build output

DUB version 1.41.0, built on Mar  1 2026
LDC - the LLVM D compiler (1.42.0):
  based on DMD v2.112.1 and LLVM 21.1.8
  built with LDC - the LLVM D compiler (1.42.0)
  Default target: x86_64-unknown-linux-gnu
  Host CPU: znver3
  https://dlang.org - https://wiki.dlang.org/LDC


  Registered Targets:
    aarch64     - AArch64 (little endian)
    aarch64_32  - AArch64 (little endian ILP32)
    aarch64_be  - AArch64 (big endian)
    amdgcn      - AMD GCN GPUs
    arm         - ARM
    arm64       - ARM64 (little endian)
    arm64_32    - ARM64 (little endian ILP32)
    armeb       - ARM (big endian)
    avr         - Atmel AVR Microcontroller
    bpf         - BPF (host endian)
    bpfeb       - BPF (big endian)
    bpfel       - BPF (little endian)
    hexagon     - Hexagon
    lanai       - Lanai
    loongarch32 - 32-bit LoongArch
    loongarch64 - 64-bit LoongArch
    mips        - MIPS (32-bit big endian)
    mips64      - MIPS (64-bit big endian)
    mips64el    - MIPS (64-bit little endian)
    mipsel      - MIPS (32-bit little endian)
    msp430      - MSP430 [experimental]
    nvptx       - NVIDIA PTX 32-bit
    nvptx64     - NVIDIA PTX 64-bit
    ppc32       - PowerPC 32
    ppc32le     - PowerPC 32 LE
    ppc64       - PowerPC 64
    ppc64le     - PowerPC 64 LE
    r600        - AMD GPUs HD2XXX-HD6XXX
    riscv32     - 32-bit RISC-V
    riscv64     - 64-bit RISC-V
    sparc       - Sparc
    sparcel     - Sparc LE
    sparcv9     - Sparc V9
    spirv       - SPIR-V Logical
    spirv32     - SPIR-V 32-bit
    spirv64     - SPIR-V 64-bit
    systemz     - SystemZ
    thumb       - Thumb
    thumbeb     - Thumb (big endian)
    ve          - VE
    wasm32      - WebAssembly 32-bit
    wasm64      - WebAssembly 64-bit
    x86         - 32-bit X86: Pentium-Pro and above
    x86-64      - 64-bit X86: EM64T and AMD64
    xcore       - XCore
    xtensa      - Xtensa 32
   Upgrading project in /home/runner/work/dub/dub/
    Starting Performing "release" build using /opt/hostedtoolcache/dc/ldc2-1.42.0/x64/ldc2-1.42.0-linux-x86_64/bin/ldc2 for x86_64.
    Building dub 1.42.0-beta.1+commit.4.ge6de8b76: building configuration [application]
     Linking dub
STAT:statistics (-before, +after)
STAT:executable size=5710288 bin/dub
STAT:rough build time=68s

[Copilot]

Pull request overview

Fixes a long-standing issue where command hooks defined in the root package’s custom buildType were being applied to dependency targets, causing dependency builds to execute the root project’s commands.

Changes:

• Strip all command-hook fields (and their corresponding environment maps) from root buildType settings when applying build-type settings to non-root packages.
• Add a regression unittest ensuring command hooks from a root custom build type appear only for the root package and not dependencies.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
source/dub/project.d	Clears command hooks/envs from root buildType settings when propagating to dependencies.
source/dub/test/others.d	Adds unittest coverage for issue #2598 to prevent command-hook propagation to dependencies.

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[Copilot]

In this unittest, GeneratorSettings is only partially initialized (only buildType is set). To avoid the test depending on BuildPlatform.init behavior, consider explicitly setting gsettings.platform (e.g., BuildPlatform.any) so addBuildTypeSettings is exercised with a valid platform value.