Handle missing kotlinc gracefully

Author: smowton

java/kotlin-extractor/build.py

@@ -201,6 +201,10 @@ def compile_standalone(version):
             'build/temp_src',
             version)
 
+if shutil.which(kotlinc) == None:
+    print("Cannot build the Kotlin extractor: no '%s' found on your PATH" % kotlinc, file = sys.stderr)
+    sys.exit(1)
+
 if args.many:
     for version in kotlin_plugin_versions.many_versions:
         compile_standalone(version)

java/kotlin-extractor/kotlin_plugin_versions.py

@@ -22,9 +22,15 @@ def version_string_to_tuple(version):
 
 many_versions_tuples = [version_string_to_tuple(v) for v in many_versions]
 
+class KotlincNotFoundException(Exception):
+    pass
+
 def get_single_version(fakeVersionOutput = None):
     # TODO: `shell=True` is a workaround to get CI working on Windows. It breaks the build on Linux.
-    versionOutput = subprocess.run(['kotlinc', '-version'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True, shell=is_windows()).stderr if fakeVersionOutput is None else fakeVersionOutput
+    try:
+        versionOutput = subprocess.run(['kotlinc', '-version'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True, shell=is_windows()).stderr if fakeVersionOutput is None else fakeVersionOutput
+    except FileNotFoundError as e:
+        raise KotlincNotFoundException(e)
     m = re.match(r'.* kotlinc-jvm ([0-9]+\.[0-9]+\.[0-9]+) .*', versionOutput)
     if m is None:
         raise Exception('Cannot detect version of kotlinc (got ' + str(versionOutput) + ')')