GPU: Shader Preprocess: Add support for template inside namespaces

And also support for template definition on single line.

source/blender/gpu/glsl_preprocess/glsl_preprocess.hh

@@ -687,12 +687,17 @@ class Preprocessor {
       std::string out_content = content;
 
       /* Parse all global symbols (struct / functions) inside the content. */
-      std::regex regex(R"(\n(?:const )?\w+ (\w+)\(?)");
+      std::regex regex(R"([\n\>] ?(?:const )?(\w+) (\w+)\(?)");
       regex_global_search(content, regex, [&](const std::smatch &match) {
-        std::string function = match[1].str();
+        std::string return_type = match[1].str();
+        if (return_type == "template") {
+          /* Matched a template instantiation. */
+          return;
+        }
+        std::string function = match[2].str();
         /* Replace all occurrences of the non-namespace specified symbol.
          * Reject symbols that contain the target symbol name. */
-        std::regex regex(R"(([^:\w]))" + function + R"(([\s\(]))");
+        std::regex regex(R"(([^:\w]))" + function + R"(([\s\(\<]))");
         out_content = std::regex_replace(
             out_content, regex, "$1" + namespace_name + "::" + function + "$2");
       });

source/blender/gpu/tests/shader_preprocess_test.cc

@@ -682,6 +682,35 @@ using C = B::func;
               "from the same namespace declared in another scope, potentially from another "
               "file.");
   }
+  {
+    /* Template on the same line as function signature inside a namespace.
+     * Template instantiation with other functions. */
+    string input = R"(
+namespace NS {
+template<typename T> T read(T a)
+{
+  return a;
+}
+template float read<float>(float);
+float write(float a){ return a; }
+}
+)";
+
+    string expect = R"(
+
+#define NS_read_TEMPLATE(T) T NS_read(T a) \
+{ \
+  return a; \
+}
+NS_read_TEMPLATE(float)/*float*/
+float NS_write(float a){ return a; }
+
+)";
+    string error;
+    string output = process_test_string(input, error);
+    EXPECT_EQ(output, expect);
+    EXPECT_EQ(error, "");
+  }
 }
 GPU_TEST(preprocess_namespace);