[Impeller] Validation logs indicate where in code the validation error happened.

Earlier, all validation logs originated from validation.cc which was not
useful at all since you had to find the string in the source.

Author: chinmaygarde

impeller/base/validation.cc

@@ -33,31 +33,30 @@ ScopedValidationFatal::~ScopedValidationFatal() {
   sValidationLogsAreFatal--;
 }
 
-ValidationLog::ValidationLog() = default;
+ValidationLog::ValidationLog(const char* file, int line)
+    : file_(file), line_(line) {}
 
 ValidationLog::~ValidationLog() {
   if (sValidationLogsDisabledCount <= 0) {
-    ImpellerValidationBreak(stream_.str().c_str());
+    ImpellerValidationBreak(stream_.str().c_str(), file_, line_);
   }
 }
 
 std::ostream& ValidationLog::GetStream() {
   return stream_;
 }
 
-void ImpellerValidationBreak(const char* message) {
-  std::stringstream stream;
+void ImpellerValidationBreak(const char* message, const char* file, int line) {
+  const auto severity =
+      ImpellerValidationErrorsAreFatal() ? fml::LOG_FATAL : fml::LOG_ERROR;
+  auto fml_log = fml::LogMessage{severity, file, line, nullptr};
+  fml_log.stream() <<
 #if FLUTTER_RELEASE
-  stream << "Impeller validation: " << message;
-#else
-  stream << "Break on '" << __FUNCTION__
-         << "' to inspect point of failure: " << message;
-#endif
-  if (sValidationLogsAreFatal > 0) {
-    FML_LOG(FATAL) << stream.str();
-  } else {
-    FML_LOG(ERROR) << stream.str();
-  }
+      "Impeller validation: " << message;
+#else   // FLUTTER_RELEASE
+      "Break on '" << __FUNCTION__
+                   << "' to inspect point of failure: " << message;
+#endif  // FLUTTER_RELEASE
 }
 
 bool ImpellerValidationErrorsAreFatal() {

impeller/base/validation.h

@@ -11,13 +11,15 @@ namespace impeller {
 
 class ValidationLog {
  public:
-  ValidationLog();
+  ValidationLog(const char* file, int line);
 
   ~ValidationLog();
 
   std::ostream& GetStream();
 
  private:
+  const char* file_ = nullptr;
+  int line_ = 0;
   std::ostringstream stream_;
 
   ValidationLog(const ValidationLog&) = delete;
@@ -29,7 +31,7 @@ class ValidationLog {
   ValidationLog& operator=(ValidationLog&&) = delete;
 };
 
-void ImpellerValidationBreak(const char* message);
+void ImpellerValidationBreak(const char* message, const char* file, int line);
 
 void ImpellerValidationErrorsSetFatal(bool fatal);
 
@@ -70,6 +72,6 @@ struct ScopedValidationFatal {
 ///   are fatal. The runtime-mode restriction still applies. This usually
 ///   happens in test environments.
 ///
-#define VALIDATION_LOG ::impeller::ValidationLog{}.GetStream()
+#define VALIDATION_LOG ::impeller::ValidationLog{__FILE__, __LINE__}.GetStream()
 
 #endif  // FLUTTER_IMPELLER_BASE_VALIDATION_H_