Switch over to using explicit tags and branches when invoking build-docker/local

Also, force the full Swift compiler to be built from source when building from a
branch, since there are no existing toolchain builds of arbitrary commits that
we can download.

Author: finagolfin

swift-ci/sdks/android/README.md

@@ -16,20 +16,15 @@ $ ./build-docker <version> <workdir>
 for example:
 
 ```
-$ ./build-docker release /tmp/android-sdk
+$ ./build-docker tag:swift-6.2-RELEASE /tmp/android-sdk
 ```
 
 This will create an Ubuntu 24.04 container with the necessary dependencies
 to build the Android SDK, including a Swift host toolchain and the
 Android NDK that will be used for cross-compilation.
 
-The `version` argument can be one of the following values:
-
-| version | Swift version example |
-| --- | --- |
-| `release` | swift-6.1-RELEASE |
-| `swift-6.2-branch` | swift-6.2-DEVELOPMENT-SNAPSHOT-yyyy-mm-dd |
-| `development` | swift-DEVELOPMENT-SNAPSHOT-yyyy-mm-dd |
+The `version` argument can be a branch scheme, like "scheme:release/6.2", or a
+tag, like "tag:swift-6.2-DEVELOPMENT-SNAPSHOT-2025-09-04-a".
 
 > [!WARNING]
 > The workdir argument must not be located in a git repository (e.g., it cannot be the
@@ -41,7 +36,7 @@ The top-level `./build-docker` script installs a host toolchain and the
 Android NDK, and then invokes `scripts/fetch-source.sh` which will
 fetch tagged sources for libxml2, curl, boringssl, and swift.
 
-It then applies some patches and invokes `scripts/build.sh`,
+It then applies some perl substitutions and invokes `scripts/build.sh`,
 which will build the sources for each of the specified
 architectures and then combines the SDKs into a single
 artifactbundle with targetTriples for each of the supported
@@ -50,7 +45,7 @@ and Android API levels (28-35).
 
 ## Specifying Architectures
 
-By default all the supported Android architectures
+By default, all the supported Android architectures
 will be built, but this can be reduced in order to speed
 up the build. This can be useful, e.g., as part of a CI that
 validates a pull request, as building a single architecture
@@ -60,19 +55,20 @@ whereas building for all the architectures takes over an hour.
 To build an artifactbundle for just the `x86_64` architecture, run:
 
 ```
-TARGET_ARCHS=x86_64 ./build-docker release /tmp/android-sdk
+TARGET_ARCHS=x86_64 ./build-docker scheme:main /tmp/android-sdk
 ```
 
-## Installing and validating the SDK
+## Building the Swift compiler from source and running the validation suite
 
-The `.github/workflows/pull_request.yml` workflow
-will create and upload an installable SDK named something like:
-`swift-6.1-RELEASE_android-0.1.artifactbundle.tar.gz`
+All tags that are specified will download the official release or snapshot
+toolchain and build only the bundle by default, while building from a branch
+scheme always builds the full Swift compiler from the latest commit in that
+branch. If you want to build the Swift compiler from source for a tag also and
+run the compiler validation suite, specify the `BUILD_COMPILER` variable:
 
-The GitHub workflow will also install the SDK locally and use
-[swift-android-action](https://github.com/marketplace/actions/swift-android-action)
-to build and test various Swift packages in an Android emulator using the
-freshly-created SDK bundle.
+```
+BUILD_COMPILER=yes ./build-docker tag:swift-DEVELOPMENT-SNAPSHOT-2025-09-04-a /tmp/android-sdk
+```
 
 ## Building locally
 
@@ -85,5 +81,5 @@ a GitHub runner). A local build can be run with the
 `build-local` script, such as:
 
 ```
-./build-local swift-6.2-branch /tmp/android-sdk-devel
+./build-local scheme:release/6.2 /tmp/android-sdk
 ```

swift-ci/sdks/android/build-docker

@@ -23,7 +23,7 @@ ANDROID_API=28
 BASEPATH=$(dirname $(realpath $0))
 cd ${BASEPATH}
 
-export BUILD_SCHEME=${1}
+export SWIFT_VERSION=${1}
 # note that WORKDIR must not be under the current checkout or the patches will fail to apply
 WORKDIR=${2}
 if [[ "${WORKDIR}" == '' ]]; then
@@ -34,18 +34,15 @@ mkdir -p ${WORKDIR}
 WORKDIR=$(realpath ${WORKDIR})
 
 HOST_OS=ubuntu24.04
+if [[ $SWIFT_VERSION == scheme:* ]]; then
+    BUILD_COMPILER=yes
+    echo "Branch scheme builds always build the Swift compiler from source and take much longer."
+fi
+
 source ./scripts/toolchain-vars.sh
 
 # Check-out and patch the sources
-if [[ "${BUILD_COMPILER}" != "1" ]]; then
-    ./scripts/fetch-source.sh --source-dir ${WORKDIR}/source --swift-tag ${SWIFT_TAG}
-else
-    if [[ "${BUILD_SCHEME}" == "development" ]]; then
-        ./scripts/fetch-source.sh --source-dir ${WORKDIR}/source --swift-scheme main
-    else
-        ./scripts/fetch-source.sh --source-dir ${WORKDIR}/source --swift-scheme release/6.2
-    fi
-fi
+./scripts/fetch-source.sh --source-dir ${WORKDIR}/source
 
 # This `git grep` invocation in a trunk test fails in our Docker for some
 # reason, so just turn it into a plain `grep` again.

swift-ci/sdks/android/build-local

@@ -23,7 +23,7 @@ ANDROID_API=28
 BASEPATH=$(dirname $(realpath $0))
 cd ${BASEPATH}
 
-export BUILD_SCHEME=${1}
+export SWIFT_VERSION=${1}
 # note that WORKDIR must not be under the current checkout or the patches will fail to apply
 WORKDIR=${2}
 if [[ "${WORKDIR}" == '' ]]; then
@@ -34,20 +34,29 @@ mkdir -p ${WORKDIR}
 WORKDIR=$(realpath ${WORKDIR})
 
 HOST_OS=ubuntu$(lsb_release -sr)
+if [[ $SWIFT_VERSION == scheme:* ]]; then
+    BUILD_COMPILER=yes
+    echo "Branch scheme builds always build the Swift compiler from source and take much longer."
+fi
+
 source ./scripts/toolchain-vars.sh
 
-if [[ "${BUILD_COMPILER}" != "1" ]]; then
-    SWIFT_ROOT=${WORKDIR}/host-toolchain
-    HOST_TOOLCHAIN=$SWIFT_ROOT/$SWIFT_BASE/usr
-    if [[ ! -d "$HOST_TOOLCHAIN" ]]; then
-        ./scripts/install-swift.sh ${HOST_TOOLCHAIN}
-    fi
+case $BUILD_COMPILER in
+    1|true|yes|YES)
+        ;;
+    *)
+        SWIFT_ROOT=${WORKDIR}/host-toolchain
+        HOST_TOOLCHAIN=$SWIFT_ROOT/$SWIFT_BASE/usr
+        if [[ ! -d "$HOST_TOOLCHAIN" ]]; then
+            ./scripts/install-swift.sh ${HOST_TOOLCHAIN}
+        fi
 
-    $HOST_TOOLCHAIN/bin/swift --version
+        $HOST_TOOLCHAIN/bin/swift --version
 
-    # ensure the correct Swift is first in the PATH
-    export PATH=$HOST_TOOLCHAIN/bin:$PATH
-fi
+        # ensure the correct Swift is first in the PATH
+        export PATH=$HOST_TOOLCHAIN/bin:$PATH
+    ;;
+esac
 
 export ANDROID_NDK_HOME=${WORKDIR}/ndk/${ANDROID_NDK_VERSION}
 
@@ -62,7 +71,7 @@ fi
 
 
 # Check-out and patch the sources
-./scripts/fetch-source.sh --source-dir ${WORKDIR}/source --swift-tag ${SWIFT_TAG}
+./scripts/fetch-source.sh --source-dir ${WORKDIR}/source
 # This `git grep` invocation in a trunk test fails in our Docker for some
 # reason, so just turn it into a plain `grep` again.
 perl -pi -e 's:"git",:#:' ${WORKDIR}/source/swift-project/swift/test/Misc/verify-swift-feature-testing.test-sh

swift-ci/sdks/android/scripts/fetch-source.sh

@@ -86,8 +86,8 @@ EOF
 }
 
 # Defaults
-if [[ -z "${SWIFT_VERSION}" ]]; then
-    SWIFT_VERSION=scheme:release/6.1
+if [[ -z "${SWIFT_VERSION}" || ($SWIFT_VERSION != scheme:* && $SWIFT_VERSION != tag:*) ]]; then
+    SWIFT_VERSION=scheme:release/6.2
 fi
 if [[ -z "${BORINGSSL_VERSION}" ]]; then
     BORINGSSL_VERSION=fips-20220613

swift-ci/sdks/android/scripts/toolchain-vars.sh

@@ -6,7 +6,7 @@
 #
 #  This source file is part of the Swift.org open source project
 #
-#  Copyright (c) 2024 Apple Inc. and the Swift project authors
+#  Copyright (c) 2025 Apple Inc. and the Swift project authors
 #  Licensed under Apache License v2.0 with Runtime Library Exception
 #
 #  See https://swift.org/LICENSE.txt for license information
@@ -15,10 +15,9 @@
 # ===----------------------------------------------------------------------===
 
 # This script is meant to be sourced from another script that sets the
-# BUILD_SCHEME environment variable to one of "release", "swift-VERSION-branch", or "development"
-# and will set check the latest builds for each build type in order
-# to provide information about the Swift tag name in use and where to
-# obtain the latest toolchain for building.
+# SWIFT_VERSION environment variable to one of "scheme:release/6.2" or
+# "tag:swift-6.2-RELEASE" and will get the latest builds for each build
+# type.
 
 OS=$(echo $HOST_OS | tr -d '.')
 # e.g., "swift-6.1-RELEASE"
@@ -27,22 +26,31 @@ RELEASE_TAG=$(curl -fsSL https://www.swift.org/api/v1/install/releases.json | jq
 # e.g., "swift-6.1-release"
 RELEASE_BRANCH=$(echo "${RELEASE_TAG}" | tr '[A-Z]' '[a-z]')
 
-case "${BUILD_SCHEME}" in
-    release)
-        export SWIFT_TAG=$RELEASE_TAG
-        export SWIFT_BRANCH=$RELEASE_BRANCH
-        ;;
-    development|swift-*-branch)
-        # e.g., swift-6.2-DEVELOPMENT-SNAPSHOT-2025-05-15-a
-        # e.g., swift-DEVELOPMENT-SNAPSHOT-2025-05-14-a
-        export SWIFT_TAG=$(curl -fsSL https://download.swift.org/$BUILD_SCHEME/$OS/latest-build.yml | grep '^dir: ' | cut -f 2 -d ' ')
-        export SWIFT_BRANCH=$BUILD_SCHEME
-        ;;
+if [[ $SWIFT_VERSION == tag:* ]]; then
+    SWIFT_TAG=${SWIFT_VERSION#tag:}
+    case "${SWIFT_TAG}" in
+        swift-*-RELEASE)
+            SWIFT_BRANCH=$(echo "${SWIFT_TAG}" | tr '[A-Z]' '[a-z]')
+            ;;
+        swift-6.*-DEVELOPMENT-SNAPSHOT-*)
+            # e.g., swift-6.2-DEVELOPMENT-SNAPSHOT-2025-05-15-a
+            SWIFT_BRANCH=${SWIFT_TAG//DEVEL*/branch}
+            ;;
+        swift-DEVELOPMENT-SNAPSHOT-*)
+            # e.g., swift-DEVELOPMENT-SNAPSHOT-2025-05-14-a
+            SWIFT_BRANCH=development
+            ;;
     *)
-        echo "$0: invalid BUILD_SCHEME=${BUILD_SCHEME}"
+        echo "$0: invalid tag=${SWIFT_TAG}"
         exit 1
         ;;
-esac
+    esac
+elif [[ $SWIFT_VERSION == scheme:* ]]; then
+    echo "Building $SWIFT_VERSION with prebuilt Swift $RELEASE_TAG compiler"
+else
+    echo "Invalid Swift version=${SWIFT_VERSION}"
+    exit 1
+fi
 
 SWIFT_BASE=$SWIFT_TAG-$HOST_OS