fix: distinguish build matrix build type from Makefile's BUILD_TYPE

build-neon uses `make postgres-...`.

The Makefile expects BUILD_TYPE to be debug or release.

Before this PR, the build matrix's BUILD_TYPE would be just that.
Now the build matrix's build type is something different than the
Makefile's BUILD_TYPE.

Make the difference explicit.

.github/workflows/build_and_test.yml

@@ -139,9 +139,13 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        build_type: [ debug, release, image ]
+        build_type:
+          - debug
+          - release
+          - image
     env:
-      BUILD_TYPE: ${{ matrix.build_type }}
+      # NB: BUILD_TYPE != MATRIX_BUILD_TYPE; the former is a Makefile variable
+      MATRIX_BUILD_TYPE: ${{ matrix.build_type }}
       GIT_VERSION: ${{ github.sha }}
 
     steps:
@@ -181,18 +185,20 @@ jobs:
       # corresponding Cargo.toml files for their descriptions.
       - name: Set env variables
         run: |
-          case "$BUILD_TYPE" in
+          case "$MATRIX_BUILD_TYPE" in
             debug)
               cov_prefix="scripts/coverage --profraw-prefix=$GITHUB_JOB --dir=/tmp/coverage run"
               CARGO_FEATURES="--features testing"
               CARGO_FLAGS="--locked"
               TARGET_DIR_NAME="debug"
+              BUILD_TYPE="debug"
               ;;
             release)
               cov_prefix=""
               CARGO_FEATURES="--features testing"
               CARGO_FLAGS="--locked --release"
               TARGET_DIR_NAME="release"
+              BUILD_TYPE="release"
               ;;
             image)
               # Like we do in the Dockerfile built by the neon-image stage.
@@ -202,9 +208,10 @@ jobs:
               CARGO_FEATURES=""
               CARGO_FLAGS="--locked --release"
               TARGET_DIR_NAME="release"
+              BUILD_TYPE="release"
               ;;
             *)
-              echo "Unknown BUILD_TYPE: $BUILD_TYPE"
+              echo "Unknown MATRIX_BUILD_TYPE: $MATRIX_BUILD_TYPE"
               exit 1
               ;;
           esac
@@ -213,6 +220,8 @@ jobs:
           echo "CARGO_FLAGS=${CARGO_FLAGS}" >> $GITHUB_ENV
           echo "CARGO_HOME=${GITHUB_WORKSPACE}/.cargo" >> $GITHUB_ENV
           echo "TARGET_DIR_NAME=${TARGET_DIR_NAME}" >> $GITHUB_ENV
+          echo "MATRIX_BUILD_TYPE=${MATRIX_BUILD_TYPE}" >> $GITHUB_ENV
+          echo "BUILD_TYPE=${BUILD_TYPE}" >> $GITHUB_ENV
 
       # Disabled for now
       # Don't include the ~/.cargo/registry/src directory. It contains just
@@ -288,7 +297,7 @@ jobs:
           done
 
           # Install test executables and write list of all binaries (for code coverage)
-          if [[ $BUILD_TYPE == "debug" ]]; then
+          if [[ $MATRIX_BUILD_TYPE == "debug" ]]; then
             # Keep bloated coverage data files away from the rest of the artifact
             mkdir -p /tmp/coverage/
 
@@ -313,7 +322,7 @@ jobs:
             done
           else
             if [ "$cov_prefix" != "" ]; then
-              echo "expecting coverage prefix to be empty for all build types except debug, got BUILD_TYPE=$BUILD_TYPE"
+              echo "expecting coverage prefix to be empty for all gh matrix build types except 'debug', got MATRIX_BUILD_TYPE=$MATRIX_BUILD_TYPE"
               exit 1
             fi
           fi