Improve errors in variable definitions by adding labels to the variables.

BEGIN_PUBLIC
Improve errors in variable definitions by adding labels to the variables.
END_PUBLIC

PiperOrigin-RevId: 618984216
Change-Id: I5d6d11ba2b72f426b9f01bcbb528b0914c98c964

cc/toolchains/cc_toolchain_info.bzl

@@ -50,6 +50,7 @@ VariableInfo = provider(
     # @unsorted-dict-items
     fields = {
         "name": "(str) The variable name",
+        "label": "(Label) The label defining this provider. Place in error messages to simplify debugging",
         "actions": "(Optional[depset[ActionTypeInfo]]) The actions this variable is available for",
         "type": "A type constructed using variables.types.*",
     },
@@ -58,7 +59,7 @@ VariableInfo = provider(
 BuiltinVariablesInfo = provider(
     doc = "The builtin variables",
     fields = {
-        "variables": "(dict[str, struct(type=type, actions=Optional[depset[ActionTypeInfo]]) A mapping from variable name to variable metadata.",
+        "variables": "(dict[str, VariableInfo]) A mapping from variable name to variable metadata.",
     },
 )
 

cc/toolchains/impl/variables.bzl

@@ -52,6 +52,7 @@ types = struct(
 def _cc_variable_impl(ctx):
     return [VariableInfo(
         name = ctx.label.name,
+        label = ctx.label,
         type = json.decode(ctx.attr.type),
         actions = collect_action_types(ctx.attr.actions) if ctx.attr.actions else None,
     )]
@@ -84,10 +85,7 @@ def cc_variable(name, type, **kwargs):
 
 def _cc_builtin_variables_impl(ctx):
     return [BuiltinVariablesInfo(variables = {
-        variable.name: struct(
-            actions = variable.actions,
-            type = variable.type,
-        )
+        variable.name: variable
         for variable in collect_provider(ctx.attr.srcs, VariableInfo)
     })]
 
@@ -131,7 +129,7 @@ def get_type(*, name, variables, overrides, actions, args_label, nested_label, f
         for action in actions:
             if action not in valid_actions:
                 fail("The variable {var} is inaccessible from the action {action}. This is required because it is referenced in {nested_label}, which is included by {args_label}, which references that action".format(
-                    var = outer,
+                    var = variables[outer].label,
                     nested_label = nested_label,
                     args_label = args_label,
                     action = action.label,

tests/rule_based_toolchain/variables/variables_test.bzl

@@ -84,7 +84,7 @@ nested_str_list: List[string]""")
 
     expect_type("struct", actions = [c_compile]).ok()
     expect_type("struct", actions = [c_compile, cpp_compile]).err().equals(
-        "The variable struct is inaccessible from the action %s. This is required because it is referenced in %s, which is included by %s, which references that action" % (cpp_compile.label, _NESTED_LABEL, _ARGS_LABEL),
+        "The variable %s is inaccessible from the action %s. This is required because it is referenced in %s, which is included by %s, which references that action" % (targets.struct.label, cpp_compile.label, _NESTED_LABEL, _ARGS_LABEL),
     )
 
     expect_type("struct.nested_str_list", actions = [c_compile]).ok()