allow renaming function Params structs

Author: skandragon

docs/howto/rename.md

@@ -21,7 +21,7 @@ sql:
   queries: "postgresql/query.sql"
   engine: "postgresql"
   gen:
-    go: 
+    go:
       package: "authors"
       out: "postgresql"
       rename:
@@ -116,6 +116,28 @@ type Publisher struct {
 }
 ```
 
+## Parameter Structure Names
+
+It is possible to rename the arguments a generated function would use.
+For example, if you had a generated function called `FindWriter`
+which used a generated name of `FindWriterParams`, you can choose to rename
+this:
+
+```yaml
+version: "2"
+sql:
+  - engine: postgresql
+    queries: query.sql
+    schema: query.sql
+overrides:
+  go:
+    rename:
+      FindWriterParams: SomeOtherNameParams
+```
+
+The target name must be unique, and even if multiple structures would
+have the same fields, there will be a conflict.
+
 ## Limitations
 
 Rename mappings apply to an entire package. Therefore, a column named `foo` and

internal/codegen/golang/result.go

@@ -353,7 +353,7 @@ func putOutColumns(query *plugin.Query) bool {
 // This is unlikely to happen, so don't fix it yet
 func columnsToStruct(req *plugin.GenerateRequest, options *opts.Options, name string, columns []goColumn, useID bool) (*Struct, error) {
 	gs := Struct{
-		Name: name,
+		Name: CheckRename(name, options),
 	}
 	seen := map[string][]int{}
 	suffixes := map[int]int{}

internal/codegen/golang/struct.go

@@ -16,6 +16,13 @@ type Struct struct {
 	Comment string
 }
 
+func CheckRename(name string, options *opts.Options) string {
+	if rename := options.Rename[name]; rename != "" {
+		return rename
+	}
+	return name
+}
+
 func StructName(name string, options *opts.Options) string {
 	if rename := options.Rename[name]; rename != "" {
 		return rename