From 3f9a434e4bfa5449234fc30668ea256a52497bd5 Mon Sep 17 00:00:00 2001
From: Matt Leon <mattleon@google.com>
Date: Tue, 7 Jan 2025 11:31:33 -0500
Subject: [PATCH] build: Upstream envoy's C++20 patch

Added in https://github.com/envoyproxy/envoy/pull/32585.

Required for https://github.com/proxy-wasm/proxy-wasm-cpp-host/pull/411

Signed-off-by: Matt Leon <mattleon@google.com>
---
 proxy_wasm_api.h | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/proxy_wasm_api.h b/proxy_wasm_api.h
index 45acdb5..9f996af 100644
--- a/proxy_wasm_api.h
+++ b/proxy_wasm_api.h
@@ -1712,8 +1712,9 @@ struct SimpleHistogram {
 template <typename... Tags> struct Counter : public MetricBase {
   static Counter<Tags...> *New(std::string_view name, MetricTagDescriptor<Tags>... fieldnames);
 
-  Counter<Tags...>(std::string_view name, MetricTagDescriptor<Tags>... descriptors)
-      : Counter<Tags...>(std::string(name), std::vector<MetricTag>({toMetricTag(descriptors)...})) {
+  template <typename... T>
+  Counter(std::string_view name, MetricTagDescriptor<T>... descriptors)
+      : Counter<T...>(std::string(name), std::vector<MetricTag>({toMetricTag(descriptors)...})) {
   }
 
   SimpleCounter resolve(Tags... f) {
@@ -1763,8 +1764,9 @@ inline Counter<Tags...> *Counter<Tags...>::New(std::string_view name,
 template <typename... Tags> struct Gauge : public MetricBase {
   static Gauge<Tags...> *New(std::string_view name, MetricTagDescriptor<Tags>... fieldnames);
 
-  Gauge<Tags...>(std::string_view name, MetricTagDescriptor<Tags>... descriptors)
-      : Gauge<Tags...>(std::string(name), std::vector<MetricTag>({toMetricTag(descriptors)...})) {}
+  template <typename... T>
+  Gauge(std::string_view name, MetricTagDescriptor<T>... descriptors)
+      : Gauge<T...>(std::string(name), std::vector<MetricTag>({toMetricTag(descriptors)...})) {}
 
   SimpleGauge resolve(Tags... f) {
     std::vector<std::string> fields{toString(f)...};
@@ -1809,8 +1811,9 @@ inline Gauge<Tags...> *Gauge<Tags...>::New(std::string_view name,
 template <typename... Tags> struct Histogram : public MetricBase {
   static Histogram<Tags...> *New(std::string_view name, MetricTagDescriptor<Tags>... fieldnames);
 
-  Histogram<Tags...>(std::string_view name, MetricTagDescriptor<Tags>... descriptors)
-      : Histogram<Tags...>(std::string(name),
+  template <typename... T>
+  Histogram(std::string_view name, MetricTagDescriptor<T>... descriptors)
+      : Histogram<T...>(std::string(name),
                            std::vector<MetricTag>({toMetricTag(descriptors)...})) {}
 
   SimpleHistogram resolve(Tags... f) {