[vcpkg.targets] Skip applocal when the installed bin directory does not exist by azchohfi · Pull Request #54330 · microsoft/vcpkg

Alexandre Zollinger Chohfi (azchohfi) · 2026-10-06T04:14:45Z

AppLocalFromInstalled runs after every link and starts vcpkg.exe z-applocal to copy DLLs from
installed\<triplet>\[debug\]bin next to the binary. When that directory does not exist, there is
nothing to copy, but the process still starts. With the user-wide integration
(vcpkg integrate install), this happens in every C++ project built with MSBuild on the machine,
including ones that use no vcpkg packages. CMake's Visual Studio generator alone builds two such
projects in every fresh configure: the compiler-ID project and the ABI try_compile.

This adds one condition to the target:

   <Target Name="AppLocalFromInstalled" AfterTargets="CopyFilesToOutputDirectory" BeforeTargets="CopyLocalFilesOutputGroup;RegisterOutput"
-          Condition="'$(_ZVcpkgClassicOrManifest)' == 'true' and '$(VcpkgApplocalDeps)' == 'true' and '$(LinkSkippedExecution)' != 'true' and '@(Link)' != ''">
+          Condition="'$(_ZVcpkgClassicOrManifest)' == 'true' and '$(VcpkgApplocalDeps)' == 'true' and '$(LinkSkippedExecution)' != 'true' and '@(Link)' != ''
+                     and Exists('$(_ZVcpkgCurrentInstalledDir)$(_ZVcpkgConfigSubdir)bin')">

The path is the same one the target already passes as --installed-bin-dir.

Manifest mode

MSBuild evaluates a target's Condition when the target is about to run, not when the project is
loaded. In manifest mode, VcpkgInstallManifestDependencies (BeforeTargets="ClCompile") has
created vcpkg_installed\<triplet>\... by then, so the check sees it. Tested below, on a project
whose vcpkg_installed did not exist before the build.

Testing

Each case is a full -t:Rebuild of a real linked C++ project, CMake's generated
CompilerIdCXX.vcxproj, at -v:d. It records whether AppLocalFromInstalled ran and what it
copied. Integration from this branch; vcpkg-tool 2026-09-26.

mode	case	`AppLocalFromInstalled`	DLL deployed
classic	no `installed\` tree, without this change	runs (`z-applocal`, copies nothing)	—
classic	no `installed\` tree, with this change	skipped	—
classic	the bin directory the target resolves for this project (`installed\x64-windows\bin`) holds a DLL the binary imports	runs	yes
manifest	dependency on an overlay port that installs a DLL into `bin` and `debug\bin`; `vcpkg_installed` absent before the build	runs, after the install step	yes
manifest	no dependencies (`vcpkg_installed` created, no `bin`)	skipped	—

No CI or test in this repository covers scripts/buildsystems/msbuild. git diff --check is
clean. Not tested: x86/arm64 triplets, static triplets, vcpkg export --nuget packages,
Release configuration.

Numbers

CMake's Visual Studio 18 generator on a two-file C++ project with the user-wide integration and no
installed\ tree. Each pass runs every case once, in rotating order; values are medians in ms,
and the brackets are the 95% bootstrap CI of the per-pass paired difference. Windows 11, i9-14900K,
MSBuild 18.10, CMake 4.4.3.

`cmake -S . -B build` / `cmake --build build`	no integration	master	master + this change	saved by this change
configure, Dev Drive	2,082	2,424	2,079	242 [192, 480]
build, Dev Drive	2,110	2,232	2,105	137 [−16, 278]
configure, C: (NTFS)	2,509	2,799	2,471	360 [197, 542]
build, C:	2,091	2,358	2,216	187 [13, 281]

This run. Integration from master 9b4c015 (2026-10-05); 12 passes, on a shared machine
(load canary 1.17 before, 1.12 after).
An earlier run on a quiet machine. Integration from a9d71f3 (2026-10-03), whose
scripts/buildsystems/msbuild files are byte-identical to master's; 11 passes:
- configure: 184 ms saved [139, 263];
- build: 93 ms saved [55, 120];
- with the change, both are within noise of no integration: configure +41 [−19, 109], build
  +1 [−20, 90].

Context

#52315 made z-applocal the default instead of pwsh applocal.ps1, which removed most of this
cost (about 1.2 s per configure on a checkout from 2025). What remains is starting vcpkg.exe
once per linked project when there is nothing to deploy.

…ot exist AppLocalFromInstalled starts vcpkg.exe z-applocal after every link, to copy DLLs from installed\<triplet>\[debug\]bin next to the binary. When that directory does not exist, there is nothing it could copy. This happens with the user-wide integration (vcpkg integrate install) in every C++ project that uses no vcpkg packages, including the compiler-identification and try_compile projects that CMake's Visual Studio generator builds. Add Exists() on that directory to the target's condition. Target conditions are evaluated when the target is about to run, so in manifest mode the directory created by VcpkgInstallManifestDependencies earlier in the same build is seen.

Copilot

Copilot review overview

🟢 Approval recommended

The focused condition uses the existing app-local path and is supported by relevant manual testing.

Review effort: Balanced
Findings: None

What changed in this PR

Avoids unnecessary MSBuild app-local deployment when the selected vcpkg binary directory is absent.

Changes:

Adds an execution-time directory existence check to AppLocalFromInstalled.
Preserves manifest-mode behavior after dependency installation.

File	Description
`scripts/buildsystems/msbuild/vcpkg.targets`	Skips app-local deployment when no installed `bin` directory exists.

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Pre-existing, reported by the PR whitespace check when the file is edited.

Billy O'Neal (BillyONeal)

Thanks for the analysis and fix!

VcpkgInstallManifestDependencies strips inherited MSBuild globals from the install child, but RemoveProperties takes precedence over Properties. When VcpkgAdditionalInstallOptions or VcpkgTriplet is supplied with /p:, it appears in both lists and is removed despite being explicitly forwarded. Project-local options work, but command-line overlay flags are lost and overlay-only dependencies fail to resolve. Define the forwarded property names and values once, exclude those names from the removal list, and escape all forwarded values consistently. Unrelated inherited globals remain isolated from the install child. This pre-existing problem was originally detected by GPT 6.1 Sol while reviewing microsoft#54330. It was not introduced by that PR. Regression coverage lives in the integrate-install-properties end-to-end suite in vcpkg-tool. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Alexandre Zollinger Chohfi (azchohfi) · 2026-10-08T06:42:45Z

Measured on two public CMake projects:

Projects: fmt 11.2.0 (FMT_TEST=ON) and GLFW 3.4 (examples and tests on).
Toolchain: Visual Studio 18 generator, Debug, x64. cmake --build with no --parallel, as most scripts run it, so one MSBuild node.
Integration: user-wide, as vcpkg integrate install writes it, with no installed\ tree. Three arms, interleaved in every pass:
- no integration;
- this repository's master (9b4c015);
- master + this PR.
Passes: 6 per arm. Each is a fresh configure followed by a full build. Windows 11, i9-14900K, Dev Drive.

	fmt	GLFW
linked projects (exe/dll) in the build	22	31
`z-applocal` runs in the build, master	22	31
`z-applocal` runs in the build, this PR	0	0
build, no integration	50.3 s	17.3 s
build, master	53.1 s	23.8 s
build, this PR	50.4 s	17.4 s
saved by this PR (paired median, 95% CI)	2.5 s (−0.9 to 6.6)	4.6 s (3.7 to 10.2)
saved, as a share of the master build	4.6%	19.3%
passes where this PR was faster	5 of 6	6 of 6
saving per linked project	~110 ms	~150 ms

With this PR, both builds are back at the no-integration time: +0.1 s on each.
The cost scales with the number of linked projects. It is about 0.1–0.15 s per exe or DLL: one vcpkg.exe start that finds nothing to copy.
Its weight depends on how long each project takes to compile. In fmt, compilation dominates, so the saving is about 5% and within noise on 6 passes. In GLFW, the projects are small C programs, so it is about a fifth of the build.
Configure builds two linked projects of its own (compiler ID and ABI check). The saving there is about 0.3 s on both projects, within noise at this sample size. An earlier 11-pass A/B on a smaller project measured 184 ms saved per configure (CI 139–263).

Not measured: --parallel builds, where the per-project cost is spread across nodes; Release; and C: drives.

Copilot AI balanced review requested due to automatic review settings October 6, 2026 04:14

Copilot started reviewing on behalf of Alexandre Zollinger Chohfi (azchohfi) October 6, 2026 04:15 View session

Copilot AI reviewed Oct 6, 2026

View reviewed changes

[vcpkg.targets] Remove trailing whitespace

0af0210

Pre-existing, reported by the PR whitespace check when the file is edited.

Billy O'Neal (BillyONeal) approved these changes Oct 6, 2026

View reviewed changes

Billy O'Neal (BillyONeal) merged commit 001713e into microsoft:master Oct 6, 2026
16 checks passed

Alexandre Zollinger Chohfi (azchohfi) deleted the applocal-skip-without-installed-bin branch October 6, 2026 18:38

Billy O'Neal (BillyONeal) mentioned this pull request Oct 6, 2026

[vcpkg.targets] Preserve explicit manifest install properties #54341

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[vcpkg.targets] Skip applocal when the installed bin directory does not exist - #54330

[vcpkg.targets] Skip applocal when the installed bin directory does not exist#54330
Billy O'Neal (BillyONeal) merged 2 commits into
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azchohfi:applocal-skip-without-installed-bin

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Alexandre Zollinger Chohfi (azchohfi) commented Oct 6, 2026

Manifest mode

Testing

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🟢 Approval recommended

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