Rename go buildtags constraints to make them more human-friendly

Summary:
Before `prelude//go/constraints:tag_sqlite__value`
After `prelude//go/tags/constraints:sqlite`

Reviewed By: awalterschulze

Differential Revision: D62521040

fbshipit-source-id: 41cbc4b93a6f1e01b4c8c6d82147321811cf6644

prelude/go/constraints/BUCK.v2

@@ -1,5 +1,4 @@
 load("@prelude//utils:source_listing.bzl", "source_listing")
-load(":defs.bzl", "generate_tag_constraints")
 
 oncall("build_infra")
 
@@ -95,5 +94,3 @@ constraint_value(
     constraint_setting = ":coverage_mode",
     visibility = ["PUBLIC"],
 )
-
-generate_tag_constraints()

prelude/go/tags/constraints/BUCK.v2

@@ -0,0 +1,8 @@
+load("@prelude//utils:source_listing.bzl", "source_listing")
+load(":defs.bzl", "generate_tag_constraints")
+
+oncall("build_infra")
+
+source_listing()
+
+generate_tag_constraints()

prelude/go/constraints/defs.bzl → prelude/go/tags/constraints/defs.bzl

@@ -10,14 +10,14 @@ load("@prelude//go/transitions:tags_helper.bzl", "allowed_tags")
 
 def generate_tag_constraints():
     for tag in allowed_tags:
-        setting_name = "tag_" + tag
+        setting_name = "setting__" + tag
         native.constraint_setting(
-            name = "tag_" + tag,
+            name = setting_name,
             visibility = ["PUBLIC"],
         )
 
         native.constraint_value(
-            name = setting_name + "__value",
+            name = tag,
             constraint_setting = ":" + setting_name,
             visibility = ["PUBLIC"],
         )

prelude/go/transitions/tags_helper.bzl

@@ -10,14 +10,14 @@ load("@prelude//utils:buckconfig.bzl", "read_list")
 allowed_tags = read_list("go", "allowed_tags", default = [], root_cell = True)
 
 def tag_to_constrant_value():
-    return {tag: "prelude//go/constraints:tag_{}__value".format(tag) for tag in allowed_tags}
+    return {tag: "prelude//go/tags/constraints:{}".format(tag) for tag in allowed_tags}
 
 def selects_for_tags():
     selects = []
     for tag in allowed_tags:
         selects += select({
             "DEFAULT": [],
-            "prelude//go/constraints:tag_{}__value".format(tag): [tag],
+            "prelude//go/tags/constraints:{}".format(tag): [tag],
         })
 
     return selects