Merge 'Add a ninja help build target' from Pekka Enberg

This pull request adds a "ninja help" build target in hopes of making
the different build targets more discoverable to developers.

Closes #8454

* github.com:scylladb/scylla:
  building.md: Document "ninja help" target
  configure.py: "ninja help" target
  building.md: Document "ninja <mode>-dist" target
  configure.py: Add <mode>-dist target as alias for dist-<mode>

configure.py

@@ -1983,7 +1983,8 @@ with open(buildfile_tmp, 'w') as f:
         build $builddir/{mode}/dist/tar/{scylla_product}-tools-package.tar.gz: copy tools/java/build/{scylla_product}-tools-package.tar.gz
         build $builddir/{mode}/dist/tar/{scylla_product}-jmx-package.tar.gz: copy tools/jmx/build/{scylla_product}-jmx-package.tar.gz
 
-        build dist-{mode}: phony dist-server-{mode} dist-python3-{mode} dist-tools-{mode} dist-jmx-{mode} dist-unified-{mode}
+        build {mode}-dist: phony dist-server-{mode} dist-python3-{mode} dist-tools-{mode} dist-jmx-{mode} dist-unified-{mode}
+        build dist-{mode}: phony {mode}-dist
         build dist-check-{mode}: dist-check
           mode = {mode}
             '''))
@@ -2025,6 +2026,9 @@ with open(buildfile_tmp, 'w') as f:
         rule extract_node_exporter
             command = tar -C build -xvpf {node_exporter_filename} && rm -rfv build/node_exporter && mv -v build/{node_exporter_dirname} build/node_exporter
         build $builddir/node_exporter: extract_node_exporter | always
+        rule print_help
+             command = ./scripts/build-help.sh
+        build help: print_help | always
         ''').format(**globals()))
 
 os.rename(buildfile_tmp, buildfile)

docs/guides/building.md

@@ -48,6 +48,12 @@ or launch a Scylla server locally with:
 ./tools/toolchain/dbuild ./build/dev/scylla --workdir tmp --developer-mode 1 --smp 1 --memory 1G
 ```
 
+For more help with build targets, run:
+
+```console
+./tools/toolchain/dbuild ninja help
+```
+
 That's it!
 
 ## Configuring
@@ -114,7 +120,7 @@ To build packages, run:
 Alternatively, to build packages for a specific build mode, run:
 
 ```console
-./tools/toolchain/dbuild ninja dist-<mode>
+./tools/toolchain/dbuild ninja <mode>-dist
 ```
 
 To verify the packages, run:

scripts/build-help.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+cat << EOF
+usage: ninja [options] [targets...]
+
+Run \`ninja -h\` for help on supported options.
+
+Build targets:
+  build             Build artifacts for all configured build modes.
+  <mode>-build      Build artifacts for a specific build mode.
+
+Test targets:
+  test              Run tests for all configured build modes.
+  <mode>-test       Run tests for a specific build mode.
+
+Packaging targets:
+  dist              Build distribution packages (.rpm, .deb) for all build modes.
+  <mode>-dist       Build distribution packages (.rpm, .deb) for a specific build mode.
+EOF