Don't ignore "null" values in variable expansions

Replace ${var:-default} with ${var-default}.

I learned something new about shell scripting today.  From bash manual:
===
When not performing substring expansion, using the form described
below (e.g., ‘:-’), Bash tests for a parameter that is unset or null.
Omitting the colon results in a test only for a parameter that is
unset. Put another way, if the colon is included, the operator tests
for both parameter’s existence and that its value is not null; if
the colon is omitted, the operator tests only for existence.
===

The immediate problem I need to fix is handling of
host_aarchXX_excludecheck and host_x86_64_excludecheck parameters
in tcwg-buildfarm.sh.  With ":-" syntax the empty ("null") values are
replaced by defaults, causing GCC testsuite to be ignored on aarchXX
hosts when "--host_aarchXX_excludecheck ''" is given.

There happens to be a single usage ":-" in ${rw:-rw} in
start-container-qemu.sh, where ":-" is actually needed.

Change-Id: Ibc8e070b698e1c76e2161eb65d40639b8cdec1f3

1 files changed, 24 insertions, 24 deletions

diff --git a/tcwg-buildfarm.sh b/tcwg-buildfarm.sh
index c5709d6f..7fa08486 100755
--- a/tcwg-buildfarm.sh
+++ b/tcwg-buildfarm.sh
@@ -9,30 +9,30 @@ convert_args_to_variables "$@"
 
 # Make shellcheck happy and workaround Jenkins not defining variables
 # for empty arguments.
-label="${label:-tcwg-x86_64-build}"
-target="${target:-aarch64-linux-gnu}"
-NODE_NAME="${NODE_NAME:-$(hostname)}"
-TCWG_SES_USER="${TCWG_SES_USER:-}"
-TCWG_SES_PASSWORD="${TCWG_SES_PASSWORD:-}"
-WORKSPACE="${WORKSPACE:-$(pwd)}"
-override="${override:-}"
-host_x86_64_languages="${host_x86_64_languages:-default}"
-host_aarchXX_languages="${host_aarchXX_languages:-c,c++}"
-runtests="${runtests:-aarch64-linux-gnu}"
-send_results_to="${send_results_to:-}"
-try_bootstrap="${try_bootstrap:-true}"
-host_x86_64_excludecheck="${host_x86_64_excludecheck:-gdb}"
-host_aarchXX_excludecheck="${host_aarchXX_excludecheck:-gcc}"
-extraconfig="${extraconfig:-}"
-rebuild="${rebuild:-true}"
-log_name="${log_name:-$target}"
-dont_fail="${dont_fail:-false}"
-log_server="${log_server:-dev-01.tcwglab:$HOME/logs}"
-abe_branch="${abe_branch:-refs/heads/tested}"
-build_container_tag="${build_container_tag:-xenial-tcwg-tested}"
-test_container_tag="${test_container_tag:-xenial-tcwg-tested}"
-binaries="${binaries:-false}"
-dryrun="${dryrun:-false}"
+label="${label-tcwg-x86_64-build}"
+target="${target-aarch64-linux-gnu}"
+NODE_NAME="${NODE_NAME-$(hostname)}"
+TCWG_SES_USER="${TCWG_SES_USER-}"
+TCWG_SES_PASSWORD="${TCWG_SES_PASSWORD-}"
+WORKSPACE="${WORKSPACE-$(pwd)}"
+override="${override-}"
+host_x86_64_languages="${host_x86_64_languages-default}"
+host_aarchXX_languages="${host_aarchXX_languages-c,c++}"
+runtests="${runtests-aarch64-linux-gnu}"
+send_results_to="${send_results_to-}"
+try_bootstrap="${try_bootstrap-true}"
+host_x86_64_excludecheck="${host_x86_64_excludecheck-gdb}"
+host_aarchXX_excludecheck="${host_aarchXX_excludecheck-gcc}"
+extraconfig="${extraconfig-}"
+rebuild="${rebuild-true}"
+log_name="${log_name-$target}"
+dont_fail="${dont_fail-false}"
+log_server="${log_server-dev-01.tcwglab:$HOME/logs}"
+abe_branch="${abe_branch-refs/heads/tested}"
+build_container_tag="${build_container_tag-xenial-tcwg-tested}"
+test_container_tag="${test_container_tag-xenial-tcwg-tested}"
+binaries="${binaries-false}"
+dryrun="${dryrun-false}"
 
 # Jenkins doesn't define variables when parameter value is empty,
 # so enable "set -u" only after above binding of variables.