From 78c17a28d2089d4792b52fdf78176633cf2ea7b9 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Thu, 6 Feb 2025 14:07:32 +0100
Subject: [PATCH] Improve code generation to avoid unused variable warnings

The Rails test suite had these warnings for ages, which I'd like
to fix:

```
aws-sdk-s3/endpoint_provider.rb:22: warning: assigned but unused variable - key
aws-sdk-s3/endpoint_provider.rb:24: warning: assigned but unused variable - copy_source
aws-sdk-s3/endpoint_provider.rb:23: warning: assigned but unused variable - prefix
```

Ultimately I don't think pre-assigning to variables is really worth it,
as the `parameters` argument is a T_STRUCT so access is really fast.

But I suspect this was done to make the code generation simpler.
In the end this adds a little bit of complexity, but not that much.
---
 .../views/endpoint_provider_class.rb          | 25 +++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/build_tools/aws-sdk-code-generator/lib/aws-sdk-code-generator/views/endpoint_provider_class.rb b/build_tools/aws-sdk-code-generator/lib/aws-sdk-code-generator/views/endpoint_provider_class.rb
index 48eabb8a3cd..7993402f163 100644
--- a/build_tools/aws-sdk-code-generator/lib/aws-sdk-code-generator/views/endpoint_provider_class.rb
+++ b/build_tools/aws-sdk-code-generator/lib/aws-sdk-code-generator/views/endpoint_provider_class.rb
@@ -7,6 +7,7 @@ class EndpointProviderClass < View
       # @option options [required, Service] :service
       # @option options [required, Hash] :endpoint_rules
       def initialize(options)
+        @assigned_variables = []
         @service = options.fetch(:service)
         @endpoint_rules = @service.endpoint_rules
         # Used to collect metrics in the generated endpoint provider
@@ -33,10 +34,6 @@ def module_name
 
       def endpoint_rules_code
         res = StringIO.new
-        # map parameters first
-        @endpoint_rules["parameters"].each do |k,_v|
-          res << indent("#{underscore(k)} = parameters.#{underscore(k)}\n", 3)
-        end
 
         # map rules
         @endpoint_rules["rules"].each do |rule|
@@ -164,6 +161,7 @@ def conditions(conditions, level)
 
       def condition(condition)
         if condition['assign']
+          @assigned_variables << condition['assign']
           "(#{underscore(condition['assign'])} = #{fn(condition)})"
         else
           fn(condition)
@@ -173,7 +171,11 @@ def condition(condition)
       def str(s)
         if s.is_a?(Hash)
           if s['ref']
-            underscore(s['ref'])
+            if @assigned_variables.include?(s['ref'])
+              underscore(s['ref'])
+            else
+              "parameters.#{underscore(s['ref'])}"
+            end
           elsif s['fn']
             fn(s)
           else
@@ -195,7 +197,12 @@ def template_str(string, wrap=true)
 
       def template_replace(value)
         indexes = value.split("#")
-        res = underscore(indexes.shift)
+        variable = indexes.shift
+        res = if @assigned_variables.include?(variable)
+          underscore(variable)
+        else
+          "parameters.#{underscore(variable)}"
+        end
         res += indexes.map do |index|
           "['#{index}']"
         end.join("")
@@ -210,7 +217,11 @@ def fn(fn)
       def fn_arg(arg)
         if arg.is_a?(Hash)
           if arg['ref']
-            underscore(arg['ref'])
+            if @assigned_variables.include?(arg['ref'])
+              underscore(arg['ref'])
+            else
+              "parameters.#{underscore(arg['ref'])}"
+            end
           elsif arg['fn']
             fn(arg)
           else