2. Strict mode

In this section, we will cover the usage of strict vs non-strict build plans in conjunction with workspaces, and how this can help to improve your edit/compile/test cycles.

Note

This example is distributed with BuildStream in the doc/examples/strict-mode subdirectory.

2.1. Overview

When working with BuildStream to create integrations, it is typical that you have a lot of components to build, and you frequently need to modify a component at various levels of the stack. When developing one or more applications, you might want to open a workspace and fix a bug in an application, or you might need to open a workspace on a low level shared library to fix the behavior of one or more misbehaving applications.

By default, BuildStream will always choose to be deterministic in order to produce the most correct build results as possible. As such, modifying a low level library will result in rebuilding all of it’s reverse dependencies, but this can be very time consuming and inconvenient for your edit/compile/test cycles.

This is when enabling non-strict build plans can be helpful.

To illustrate the facets of how this works, this example will present a project consisting of an application which is linked both statically and dynamically linked to a common library.

2.2. Project structure

This project is mostly based on the integration commands example, as such we will ignore large parts of this project and only focus on the elements which are of specific interest.

To illustrate the relationship of these two applications and the library, let’s briefly take a look at the underlying Makefiles which are used in this project, starting with the library and followed by both Makefiles used to build the application.

2.2.1. files/libhello/Makefile

# Sample makefile for hello library
#
.PHONY: all install

all: libhello.so libhello.a

install: all
	install -d ${DESTDIR}${PREFIX}/lib
	install -d ${DESTDIR}${PREFIX}/include
	install -m 644 libhello.so ${DESTDIR}${PREFIX}/lib
	install -m 644 libhello.a ${DESTDIR}${PREFIX}/lib
	install -m 644 libhello.h ${DESTDIR}${PREFIX}/include

%.o: %.c %.h
	$(CC) -c $< -o $@ -Wall

libhello.a: libhello.o
	$(AR) rcs $@ $^

libhello.so: libhello.o
	$(CC) -shared -o $@ $<

2.2.2. files/hello/Makefile.dynamic

# Sample makefile for hello.c
#
.PHONY: all install

all: hello

install: all
	install -d ${DESTDIR}${PREFIX}/bin
	install -m 755 hello ${DESTDIR}${PREFIX}/bin

hello: hello.c
	$(CC) -Wall -o $@ $< -lhello

2.2.3. files/hello/Makefile.static

# Sample makefile for hello.c
#
.PHONY: all install

all: hello

install: all
	install -d ${DESTDIR}${PREFIX}/bin
	install -m 755 hello ${DESTDIR}${PREFIX}/bin

hello: hello.c
	$(CC) -Wall -o $@ $< /usr/lib/libhello.a

As we can see, we have a library that is distributed both as the dynamic library libhello.so and also as the static archive libhello.a.

Now let’s take a look at the two separate elements which build the application, first the dynamically linked version and then the static one.

2.2.4. elements/hello-dynamic.bst

kind: manual
description: |

  The dynamically linked hello application

# Depend on the hello library
depends:
- libhello.bst

# Stage the files/hello directory for building
sources:
  - kind: local
    path: files/hello

# Now configure the commands to run
config:

  build-commands:
  - make -f Makefile.dynamic PREFIX="%{prefix}"

  install-commands:
  - make -f Makefile.dynamic -j1 PREFIX="%{prefix}" DESTDIR="%{install-root}" install

Nothing very special to observe about this hello program, just a manual element quite similar to the one we’ve already seen in the running commands example.

2.2.5. elements/hello-static.bst

kind: manual
description: |

  The statically linked hello application

# Depend on the hello library with the strict option
#
depends:
- filename: libhello.bst
  strict: true

# Stage the files/hello directory for building
sources:
  - kind: local
    path: files/hello

# Now configure the commands to run
config:

  build-commands:
  - make -f Makefile.static PREFIX="%{prefix}"

  install-commands:
  - make -f Makefile.static -j1 PREFIX="%{prefix}" DESTDIR="%{install-root}" install

Almost the same as the dynamic element, except here we have declared the dependency to the libhello.bst element differently: this time we have enabled the strict option in the dependency declaration.

The side effect of setting this option is that hello-static.bst will be rebuilt any time that libhello.bst has changed, even when non-strict build plans have been enabled.

Tip

Some element plugins are designed to consume the content of their dependencies entirely, and output an artifact without any transient runtime dependencies, an example of this is the compose element.

In cases such as compose, it is not necessary to explicitly annotate their dependencies as strict.

It is only helpful to set the strict attribute on a dependency declaration in the case that the specific dependency relationship causes data to be consumed verbatim, as is the case with static linking.

2.3. Using the project

For the sake of brevity, let’s assume that you’ve already built all of the elements of this project, and that you want to make some changes to the libhello.bst element, and test how it might effect the hello program.

2.3.1. Everything is already built

user@host:~/strict-mode$ bst show hello-static.bst hello-dynamic.bst

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
      cached cfc97a856b683a50e0b18ee6073c6283763d6ccc3937717d60f4b7281fa5e562 libhello.bst 
      cached 27d2a1506044342dd91b6cfd0ca7ca98b5ed14d9c500b8e8beb9b2202dfb21db hello-static.bst 
      cached 4aacf94bf921018c2224754cdba580590bcdcd26a293bc770f4fd08152369bf4 hello-dynamic.bst 

2.3.2. Open a workspace and modify libhello.c

Now let’s open up a workspace on the hello library

user@host:~/strict-mode$ bst workspace open --directory workspace_libhello libhello.bst

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
[--:--:--][        ][    main:core activity                 ] STATUS  Creating workspace for element libhello.bst
[--:--:--][cfc97a85][    main:libhello.bst                  ] START   Staging sources to /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
[--:--:--][        ][    main:libhello.bst                  ] START   Staging local files into CAS
[00:00:00][        ][    main:libhello.bst                  ] SUCCESS Staging local files into CAS
[00:00:00][cfc97a85][    main:libhello.bst                  ] SUCCESS Staging sources to /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
[--:--:--][        ][    main:core activity                 ] INFO    Created a workspace for element libhello.bst

And go ahead and make a modification like this:

--- libhello.c
+++ libhello.c
@@ -5,5 +5,5 @@
 
 void hello(const char *person)
 {
-  printf("Hello %s\n", person);
+  printf("Good morning %s\n", person);
 }

2.3.3. Observing hello-dynamic.bst

Let’s take a look at the bst show output for the dynamically linked hello-dynamic.bst element.

user@host:~/strict-mode$ bst show hello-dynamic.bst

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
   buildable b7102fe1cfa4a0961e965e39f74fb115ca7f75bbc2bb5a9291543959356a2451 libhello.bst Workspace: /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
     waiting b1c96499c0a5ea7b6cca2e09a111b905ddd79aeeca01d6b6be7b21fd9f6f654d hello-dynamic.bst 

As one might expect, the libhello.bst element is ready to be built after having been modified, and the hello-dynamic.bst element is waiting for libhello.bst to be built before it can build.

Now let’s take a look at the same elements if we pass the --no-strict option to bst:

user@host:~/strict-mode$ bst --no-strict show hello-dynamic.bst

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
   buildable b7102fe1cfa4a0961e965e39f74fb115ca7f75bbc2bb5a9291543959356a2451 libhello.bst Workspace: /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
      cached 4aacf94bf921018c2224754cdba580590bcdcd26a293bc770f4fd08152369bf4 hello-dynamic.bst 

Note that this time, the libhello.bst still needs to be built, but the hello-dymamic.bst element is showing up as cached.

Tip

The bst show output will show some cache keys dimmed out in the case that they are not entirely deterministic.

Here we can see that hello-dynamic.bst is dimmed out because it will not be rebuilt against the changed libhello.bst element, and it also has a different cache key because of this.

2.3.4. Observing hello-static.bst

Now let’s observe the hello-static.bst element with strict mode disabled:

user@host:~/strict-mode$ bst --no-strict show hello-static.bst

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
   buildable b7102fe1cfa4a0961e965e39f74fb115ca7f75bbc2bb5a9291543959356a2451 libhello.bst Workspace: /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
     waiting e636e838030a7aca10060eec6a1067f4dc6b8c6c3a19824d46d2c70be4b8fc0f hello-static.bst 

Note that in this case the hello-strict.bst is going to be rebuilt even in strict mode. This is because we annotated the declaration of the libhello.bst dependency with the strict attribute.

We did this because hello-strict.bst consumes the input of libhello.bst verbatim, by way of statically linking to it, instead of merely being affected by the content of libhello.bst at runtime, as would be the case of static linking.

2.3.5. Building and running hello-dynamic.bst

Now let’s build hello-dynamic.bst with strict mode disabled.

user@host:~/strict-mode$ bst --no-strict build hello-dynamic.bst

[--:--:--][        ][    main:core activity                 ] START   Build
[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache

BuildStream Version 2.2.1
    Session Start: Wednesday, 22-05-2024 at 09:45:37
    Project:       strict-mode (/home/user/buildstream/doc/examples/strict-mode)
    Targets:       hello-dynamic.bst

User Configuration
    Configuration File:      /home/user/buildstream/doc/run-bst-ljsi0uth/buildstream.conf
    Cache Directory:         /home/user/buildstream/doc/run-bst-ljsi0uth
    Log Files:               /home/user/buildstream/doc/run-bst-ljsi0uth/logs
    Source Mirrors:          /home/user/buildstream/doc/run-bst-ljsi0uth/sources
    Build Area:              /home/user/buildstream/doc/run-bst-ljsi0uth/build
    Strict Build Plan:       No
    Maximum Fetch Tasks:     10
    Maximum Build Tasks:     4
    Maximum Push Tasks:      4
    Maximum Network Retries: 2

Project: strict-mode

    Element Plugins
        manual: core plugin
        stack:  core plugin
        import: core plugin

    Source Plugins
        local:     core plugin
        workspace: core plugin
        tar:       core plugin

Pipeline
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
   buildable b7102fe1cfa4a0961e965e39f74fb115ca7f75bbc2bb5a9291543959356a2451 libhello.bst Workspace: /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
      cached 4aacf94bf921018c2224754cdba580590bcdcd26a293bc770f4fd08152369bf4 hello-dynamic.bst 
===============================================================================
[--:--:--][b7102fe1][   fetch:libhello.bst                  ] START   strict-mode/libhello/b7102fe1-fetch.20240522-094537.log
[00:00:00][b7102fe1][   fetch:libhello.bst                  ] SUCCESS strict-mode/libhello/b7102fe1-fetch.20240522-094537.log
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   strict-mode/libhello/b7102fe1-build.20240522-094537.log
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   Staging dependencies at: /
[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS Staging dependencies at: /
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   Integrating sandbox
[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS Integrating sandbox
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   Staging sources
[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS Staging sources
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   Running commands

    make PREFIX="/usr"
    make -j1 PREFIX="/usr" DESTDIR="/buildstream-install" install

[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS Running commands
[--:--:--][b7102fe1][   build:libhello.bst                  ] START   Caching artifact
[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS Caching artifact
[00:00:00][b7102fe1][   build:libhello.bst                  ] SUCCESS strict-mode/libhello/b7102fe1-build.20240522-094537.log
[00:00:00][        ][    main:core activity                 ] SUCCESS Build

Pipeline Summary
    Total:       4
    Session:     4
    Fetch Queue: processed 1, skipped 3, failed 0 
    Build Queue: processed 1, skipped 3, failed 0

Note that the bst build command completed without having to build hello-dynamic.bst at all.

And now we can also run hello-dynamic.bst

user@host:~/strict-mode$ bst --no-strict shell hello-dynamic.bst -- hello

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
[--:--:--][4aacf94b][    main:hello-dynamic.bst             ] START   Staging dependencies
[00:00:00][4aacf94b][    main:hello-dynamic.bst             ] SUCCESS Staging dependencies
[--:--:--][4aacf94b][    main:hello-dynamic.bst             ] START   Integrating sandbox
[--:--:--][        ][    main:hello-dynamic.bst             ] START   Running commands

    ldconfig "/usr/lib"

+ sh -e -c ldconfig "/usr/lib"
[00:00:00][        ][    main:hello-dynamic.bst             ] SUCCESS Running commands
[00:00:00][4aacf94b][    main:hello-dynamic.bst             ] SUCCESS Integrating sandbox
[--:--:--][4aacf94b][    main:hello-dynamic.bst             ] STATUS  Running command

    hello

Good morning stranger

When running hello-dynamic.bst with no-strict mode, we are actually reusing the old build of hello-dynamic.bst staged against the new build of the modified libhello.bst element.

2.3.6. Building and running hello-static.bst

Finally, if we build hello-static.bst with strict mode disabled, we can see that it will be rebuilt regardless of strict mode being enabled.

user@host:~/strict-mode$ bst --no-strict build hello-static.bst

[--:--:--][        ][    main:core activity                 ] START   Build
[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache

BuildStream Version 2.2.1
    Session Start: Wednesday, 22-05-2024 at 09:45:40
    Project:       strict-mode (/home/user/buildstream/doc/examples/strict-mode)
    Targets:       hello-static.bst

User Configuration
    Configuration File:      /home/user/buildstream/doc/run-bst-ljsi0uth/buildstream.conf
    Cache Directory:         /home/user/buildstream/doc/run-bst-ljsi0uth
    Log Files:               /home/user/buildstream/doc/run-bst-ljsi0uth/logs
    Source Mirrors:          /home/user/buildstream/doc/run-bst-ljsi0uth/sources
    Build Area:              /home/user/buildstream/doc/run-bst-ljsi0uth/build
    Strict Build Plan:       No
    Maximum Fetch Tasks:     10
    Maximum Build Tasks:     4
    Maximum Push Tasks:      4
    Maximum Network Retries: 2

Project: strict-mode

    Element Plugins
        manual: core plugin
        stack:  core plugin
        import: core plugin

    Source Plugins
        local:     core plugin
        workspace: core plugin
        tar:       core plugin

Pipeline
      cached 96140a6856a5276cd062a2af48b425f332024bf2205a481fc1c965dfefa3bacd base/alpine.bst 
      cached ecfab63c8a863e21bdcecc1f2be78cfd7a03400d378710d981724674fbab7bb5 base.bst 
      cached b7102fe1cfa4a0961e965e39f74fb115ca7f75bbc2bb5a9291543959356a2451 libhello.bst Workspace: /home/user/buildstream/doc/examples/strict-mode/workspace_libhello
   buildable e636e838030a7aca10060eec6a1067f4dc6b8c6c3a19824d46d2c70be4b8fc0f hello-static.bst 
===============================================================================
[--:--:--][e636e838][   build:hello-static.bst              ] START   strict-mode/hello-static/e636e838-build.20240522-094540.log
[--:--:--][e636e838][   build:hello-static.bst              ] START   Staging dependencies at: /
[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS Staging dependencies at: /
[--:--:--][e636e838][   build:hello-static.bst              ] START   Integrating sandbox
[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS Integrating sandbox
[--:--:--][e636e838][   build:hello-static.bst              ] START   Staging sources
[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS Staging sources
[--:--:--][e636e838][   build:hello-static.bst              ] START   Running commands

    make -f Makefile.static PREFIX="/usr"
    make -f Makefile.static -j1 PREFIX="/usr" DESTDIR="/buildstream-install" install

[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS Running commands
[--:--:--][e636e838][   build:hello-static.bst              ] START   Caching artifact
[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS Caching artifact
[00:00:00][e636e838][   build:hello-static.bst              ] SUCCESS strict-mode/hello-static/e636e838-build.20240522-094540.log
[00:00:00][        ][    main:core activity                 ] SUCCESS Build

Pipeline Summary
    Total:       4
    Session:     4
    Fetch Queue: processed 0, skipped 4, failed 0 
    Build Queue: processed 1, skipped 3, failed 0

This is of course because we declared its dependency on libhello.bst as a strict dependency.

And by the same virtue, we can see that when we run the example it has properly relinked against the changed static archive, and has the updated text in the greeting:

user@host:~/strict-mode$ bst --no-strict shell hello-static.bst -- hello

[--:--:--][        ][    main:core activity                 ] START   Loading elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Loading elements
[--:--:--][        ][    main:core activity                 ] START   Resolving elements
[00:00:00][        ][    main:core activity                 ] SUCCESS Resolving elements
[--:--:--][        ][    main:core activity                 ] START   Initializing remote caches
[00:00:00][        ][    main:core activity                 ] SUCCESS Initializing remote caches
[--:--:--][        ][    main:core activity                 ] START   Query cache
[00:00:00][        ][    main:core activity                 ] SUCCESS Query cache
[--:--:--][e636e838][    main:hello-static.bst              ] START   Staging dependencies
[00:00:00][e636e838][    main:hello-static.bst              ] SUCCESS Staging dependencies
[--:--:--][e636e838][    main:hello-static.bst              ] START   Integrating sandbox
[--:--:--][        ][    main:hello-static.bst              ] START   Running commands

    ldconfig "/usr/lib"

+ sh -e -c ldconfig "/usr/lib"
[00:00:00][        ][    main:hello-static.bst              ] SUCCESS Running commands
[00:00:00][e636e838][    main:hello-static.bst              ] SUCCESS Integrating sandbox
[--:--:--][e636e838][    main:hello-static.bst              ] STATUS  Running command

    hello

Good morning stranger

2.4. Summary

In this chapter we’ve explored how to use non-strict build plans in order to avoid rebuilding reverse dependencies of a lower level element you might be working with in a workspace, consequently improving your edit/compile/test experience.

We’ve also explained how to ensure your project still works properly with non-strict build plans when some elements perform static linking (or other operations which consume data from their dependencies verbatim), by annotating dependency declarations as strict.