fbt: added support for FBT_NO_SYNC environment variable to skip submo…

…dule update at start (flipperdevices#1363)

documentation/fbt.md

@@ -10,7 +10,10 @@ Make sure that `gcc-arm-none-eabi` toolchain & OpenOCD executables are in system
 
 ## NB
 
-FBT constructs all referenced environments & their targets' dependency trees on startup. So, to keep startup time as low as possible, we're hiding construction of certain targets behind command-line options.
+* `fbt` constructs all referenced environments & their targets' dependency trees on startup. So, to keep startup time as low as possible, we're hiding construction of certain targets behind command-line options.
+* `fbt` always performs `git submodule update --init` on start, unless you set `FBT_NO_SYNC=1` in environment:
+    * On Windows, that's `set "FBT_NO_SYNC=1"` in the shell you're running `fbt` from
+    * On \*nix, it's `$ FBT_NO_SYNC=1 ./fbt ...`
 
 ## Invoking FBT
 

fbt

@@ -5,12 +5,13 @@ set -e
 SCRIPTDIR="$( dirname -- "$0"; )";
 SCONS_EP=${SCRIPTDIR}/lib/scons/scripts/scons.py
 
-if [[ -d .git ]]; then
-    git submodule update --init
-else # Not in a git repo
-    echo Not in a git repo, please clone with git clone --recursive
-    # Return error code 1 to indicate failure
-    exit 1
+if [[ -z "${FBT_NO_SYNC:-}" ]] ; then
+    if [[ -d .git ]]; then
+        git submodule update --init
+    else
+        echo Not in a git repo, please clone with git clone --recursive
+        exit 1
+    fi
 fi
 
 SCONS_DEFAULT_FLAGS="-Q --warn=target-not-built"

fbt.cmd

@@ -2,8 +2,13 @@
 
 set SCONS_EP=%~dp0\lib\scons\scripts\scons.py
 
-if exist ".git" (
-	git submodule update --init
+if [%FBT_NO_SYNC%] == [] (
+	if exist ".git" (
+		git submodule update --init
+	) else (
+		echo Not in a git repo, please clone with git clone --recursive
+		exit /b 1
+	)
 )
 
 set "SCONS_DEFAULT_FLAGS=-Q --warn=target-not-built"