Remove `set_sources_assignment_filter` function

The function has been deprecated since Oct 2020, only accepting an
empty list. All projects using it should have been converted. If
any break, they can just remove the function call.

Bug: 125
Change-Id: I49290e4fea588dc9275414479f7867515fceea6e
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/11160
Commit-Queue: Brett Wilson <brettw@chromium.org>
Reviewed-by: Brett Wilson <brettw@chromium.org>
diff --git a/docs/reference.md b/docs/reference.md
index ec19bfd..33ee391 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -58,7 +58,6 @@
     *   [rebase_path: Rebase a file or directory to another location.](#func_rebase_path)
     *   [set_default_toolchain: Sets the default toolchain name.](#func_set_default_toolchain)
     *   [set_defaults: Set default values for a target type.](#func_set_defaults)
-    *   [set_sources_assignment_filter: Deprecated feature.](#func_set_sources_assignment_filter)
     *   [split_list: Splits a list into N different sub-lists.](#func_split_list)
     *   [string_join: Concatenates a list of strings with a separator.](#func_string_join)
     *   [string_replace: Replaces substring in the given string.](#func_string_replace)
@@ -3099,12 +3098,6 @@
     configs -= [ "//tools/mything:settings" ]
   }
 ```
-### <a name="func_set_sources_assignment_filter"></a>**set_sources_assignment_filter**: Deprecated feature.
-
-```
-  This feature is deprecated. It will be removed once all usages have been
-  removed. Only supports a single argument that needs to be an empty list.
-```
 ### <a name="func_split_list"></a>**split_list**: Splits a list into N different sub-lists.
 
 ```
diff --git a/src/gn/functions.cc b/src/gn/functions.cc
index e627e2a..6acf41a 100644
--- a/src/gn/functions.cc
+++ b/src/gn/functions.cc
@@ -806,40 +806,6 @@
   return Value();
 }
 
-// set_sources_assignment_filter -----------------------------------------------
-
-const char kSetSourcesAssignmentFilter[] = "set_sources_assignment_filter";
-const char kSetSourcesAssignmentFilter_HelpShort[] =
-    "set_sources_assignment_filter: Deprecated feature.";
-const char kSetSourcesAssignmentFilter_Help[] =
-    R"(set_sources_assignment_filter: Deprecated feature.
-
-  This feature is deprecated. It will be removed once all usages have been
-  removed. Only supports a single argument that needs to be an empty list.
-)";
-
-Value RunSetSourcesAssignmentFilter(Scope* scope,
-                                    const FunctionCallNode* function,
-                                    const std::vector<Value>& args,
-                                    Err* err) {
-  if (args.size() != 1) {
-    *err = Err(function, "set_sources_assignment_filter takes one argument.");
-    return Value();
-  }
-
-  if (!args[0].VerifyTypeIs(Value::LIST, err)) {
-    return Value();
-  }
-
-  if (!args[0].list_value().empty()) {
-    *err = Err(function,
-               "set_sources_assignment_filter argument must be an empty list.");
-    return Value();
-  }
-
-  return Value();
-}
-
 // pool ------------------------------------------------------------------------
 
 const char kPool[] = "pool";
@@ -1431,7 +1397,6 @@
     INSERT_FUNCTION(RebasePath, false)
     INSERT_FUNCTION(SetDefaults, false)
     INSERT_FUNCTION(SetDefaultToolchain, false)
-    INSERT_FUNCTION(SetSourcesAssignmentFilter, false)
     INSERT_FUNCTION(SplitList, false)
     INSERT_FUNCTION(StringJoin, false)
     INSERT_FUNCTION(StringReplace, false)
diff --git a/src/gn/functions.h b/src/gn/functions.h
index dbcce39..e0af413 100644
--- a/src/gn/functions.h
+++ b/src/gn/functions.h
@@ -328,14 +328,6 @@
                              const std::vector<Value>& args,
                              Err* err);
 
-extern const char kSetSourcesAssignmentFilter[];
-extern const char kSetSourcesAssignmentFilter_HelpShort[];
-extern const char kSetSourcesAssignmentFilter_Help[];
-Value RunSetSourcesAssignmentFilter(Scope* scope,
-                                    const FunctionCallNode* function,
-                                    const std::vector<Value>& args,
-                                    Err* err);
-
 extern const char kSharedLibrary[];
 extern const char kSharedLibrary_HelpShort[];
 extern const char kSharedLibrary_Help[];