[SDK] Avoid throwing for non-string process executable names

CHANGELOG.md

@@ -24,6 +24,9 @@ Increment the:
 * [API] Remove regex from trace_state.h
   [#4570](https://github.com/open-telemetry/opentelemetry-cpp/pull/4570)
 
+* [SDK] Avoid throwing from `Resource::Create` when `process.executable.name`
+  has a non-string value and `service.name` is not set.
+  [#4535](https://github.com/open-telemetry/opentelemetry-cpp/issues/4535)
 * [SDK] Add a missing `<cstdint>` include to `predicate_factory.h`, which
   uses `uint8_t` without including the header that declares it. This relied
   on a transitive include from elsewhere in the translation unit and failed

sdk/src/resource/resource.cc

@@ -51,7 +51,12 @@ Resource Resource::Create(const ResourceAttributes &attributes, const std::strin
         resource.attributes_.find(semconv::process::kProcessExecutableName);
     if (it_process_executable_name != resource.attributes_.end())
     {
-      default_service_name += ":" + nostd::get<std::string>(it_process_executable_name->second);
+      const auto *process_executable_name =
+          nostd::get_if<std::string>(&it_process_executable_name->second);
+      if (process_executable_name != nullptr)
+      {
+        default_service_name += ":" + *process_executable_name;
+      }
     }
     resource.attributes_[semconv::service::kServiceName] = default_service_name;
   }

sdk/test/resource/resource_test.cc

@@ -14,6 +14,7 @@
 #include "opentelemetry/sdk/resource/resource.h"
 #include "opentelemetry/sdk/resource/resource_detector.h"
 #include "opentelemetry/sdk/version/version.h"
+#include "opentelemetry/semconv/incubating/process_attributes.h"
 #include "opentelemetry/semconv/service_attributes.h"
 #include "opentelemetry/semconv/telemetry_attributes.h"
 
@@ -84,6 +85,31 @@ TEST(ResourceTest, create_without_servicename)
   EXPECT_EQ(received_attributes.size(), expected_attributes.size());  // for missing service.name
 }
 
+TEST(ResourceTest, create_with_non_string_process_executable_name)
+{
+  ResourceAttributes attributes = {{semconv::process::kProcessExecutableName, true}};
+
+  auto resource                   = Resource::Create(attributes);
+  const auto &received_attributes = resource.GetAttributes();
+  auto service_name               = received_attributes.find(semconv::service::kServiceName);
+
+  ASSERT_NE(service_name, received_attributes.end());
+  EXPECT_EQ(nostd::get<std::string>(service_name->second), "unknown_service");
+}
+
+TEST(ResourceTest, create_with_process_executable_name)
+{
+  ResourceAttributes attributes = {
+      {semconv::process::kProcessExecutableName, std::string{"otel-service"}}};
+
+  auto resource                   = Resource::Create(attributes);
+  const auto &received_attributes = resource.GetAttributes();
+  auto service_name               = received_attributes.find(semconv::service::kServiceName);
+
+  ASSERT_NE(service_name, received_attributes.end());
+  EXPECT_EQ(nostd::get<std::string>(service_name->second), "unknown_service:otel-service");
+}
+
 TEST(ResourceTest, create_with_servicename)
 {
   ResourceAttributes expected_attributes = {