Allow Python to choose generator interpreter using shutil parameter to generators.

Author: cr1901

doc/source/user/build_system/generators.rst

@@ -68,6 +68,7 @@ Key                   Description
 ===================== ===========
 command               The command to run (relative to the core root) to invoke the generator. FuseSoC will pass a yaml configuration file as the first argument when calling the command.
 interpreter           If the command requires an interpreter (e.g. python or perl), this will be used called, with the string specified in `command` as the first argument, and the yaml file as the second argument.
+shutil                If `true`, use Python's `shutil.which` to find the path to the interpreter instead of the system `PATH`. Ignored if no `interpreter`.
 cache_type            If the result of the generator should be considered cacheable. Legal values are `none`, `input` or `generator`.
 file_input_parameters All parameters that are file inputs to the generator. This option can be used when `cache_type` is set to `input` if fusesoc should track if these files change.
 ===================== ===========

fusesoc/capi2/json_schema.py

@@ -317,9 +317,13 @@
               "type": "string"
             },
             "interpreter": {
-              "description": "If the command needs a custom interpreter (such as python) this will be inserted as the first argument before command when calling the generator. The interpreter needs to be on the system PATH.",
+              "description": "If the command needs a custom interpreter (such as python) this will be inserted as the first argument before command when calling the generator. If shutil is not true, the interpreter needs to be on the system PATH.",
               "type": "string"
             },
+            "shutil": {
+              "description": "If an interpreter is set, use the Python interpreter's shutil.which module to find it.",
+              "type": "boolean"
+            },
             "cache_type": {
               "description": "If the result of the generator should be considered cacheable. Legal values are *none*, *input* or *generator*.",
               "type": "string",

fusesoc/edalizer.py

@@ -601,7 +601,11 @@ def _run(self, generator_cwd):
         ]
 
         if "interpreter" in self.generator:
-            args[0:0] = [self.generator["interpreter"]]
+            if self.generator.get("shutil", False):
+                genpath = shutil.which(self.generator["interpreter"])
+                args[0:0] = [genpath]
+            else:
+                args[0:0] = [self.generator["interpreter"]]
 
         Launcher(args[0], args[1:], cwd=generator_cwd).run()