fix: Let column names not invalidate Go field names

Characters in column names that do not qualify as a Go identifier
are stripped. The title casing as applied to underscores is applied
to stripped characters.

Author: rollulus

internal/codegen/golang/struct.go

@@ -20,6 +20,15 @@ func StructName(name string, settings *plugin.Settings) string {
 		return rename
 	}
 	out := ""
+	name = strings.Map(func(r rune) rune {
+		if unicode.IsLetter(r) {
+			return r
+		}
+		if unicode.IsDigit(r) {
+			return r
+		}
+		return rune('_')
+	}, name)
 	for _, p := range strings.Split(name, "_") {
 		if p == "id" {
 			out += "ID"

internal/endtoend/testdata/codegen_struct_field_names/stdlib/README.md

@@ -0,0 +1 @@
+This tests that Go struct field names are proper Go identifiers.

internal/endtoend/testdata/codegen_struct_field_names/stdlib/go/db.go

@@ -0,0 +1,7 @@
+CREATE TABLE bar (
+    id INT NOT NULL,
+    "!!!nobody,_,-would-believe---this-...?!" INT,
+    "parent        id" INT);
+
+-- name: test :one
+SELECT * from bar limit 1;

internal/endtoend/testdata/codegen_struct_field_names/stdlib/go/models.go

@@ -0,0 +1,11 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}