Fix the use of format string arguments in the fail macro.

The recent change to add #[must_use] to the fail macro put the generated code inside a function. This unfortunately does not work with captured format arguments -- that would require a closure rather than a function.

This change moves the creation of the message out of the function to the function call site, so nothing needs to be captured. It also adjusts the existing test to exercise the aforementioned issue.

PiperOrigin-RevId: 504214102

Author: hovinenb

googletest/integration_tests/failure_due_to_fail_macro_with_format_arguments.rs

@@ -20,7 +20,8 @@ mod tests {
 
     #[google_test]
     fn just_fails() -> Result<()> {
-        fail!("Failure message with argument: {}", "An argument").and_log_failure();
+        let argument = "An argument";
+        fail!("Failure message with argument: {argument}").and_log_failure();
         Ok(())
     }
 }

googletest/src/assertions.rs

@@ -186,18 +186,18 @@ macro_rules! fail {
         // We wrap this in a function so that we can annotate it with the must_use attribute.
         // must_use on expressions is still experimental.
         #[must_use = "The assertion result must be evaluated to affect the test result."]
-        fn create_fail_result() -> $crate::Result<()> {
+        fn create_fail_result(message: String) -> $crate::Result<()> {
             Err($crate::internal::test_outcome::TestAssertionFailure::create(format!(
                 "{}\n{}",
-                format!($($message),*),
+                message,
                 $crate::internal::source_location::SourceLocation::new(
                     file!(),
                     line!(),
                     column!(),
                 ),
             )))
         }
-        create_fail_result()
+        create_fail_result(format!($($message),*))
     }};
 
     () => { fail!("Test failed") };