Add testcase and release notes

Author: zeyi2

clang-tools-extra/docs/ReleaseNotes.rst

@@ -69,7 +69,7 @@ Potentially Breaking Changes
   - `CharTypdefsToIgnore` to `CharTypedefsToIgnore` in
     :doc:`bugprone-signed-char-misuse
     <clang-tidy/checks/bugprone/signed-char-misuse>`
-  
+
 - Modified the custom message format of :doc:`bugprone-unsafe-functions
   <clang-tidy/checks/bugprone/unsafe-functions>` by assigning a special meaning
   to the character ``>`` at the start of the value of the option
@@ -394,7 +394,7 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/unhandled-self-assignment>` check by adding
   an additional matcher that generalizes the copy-and-swap idiom pattern
   detection.
-  
+
 - Improved :doc:`bugprone-unsafe-functions
   <clang-tidy/checks/bugprone/unsafe-functions>` check by hiding the default
   suffix when the reason starts with the character `>` in the `CustomFunctions`
@@ -497,7 +497,8 @@ Changes in existing checks
 - Improved :doc:`modernize-use-std-print
   <clang-tidy/checks/modernize/use-std-print>` check to correctly match
   when the format string is converted to a different type by an implicit
-  constructor call.
+  constructor call, and fixed a crash when handling format strings
+  containing non-ASCII characters.
 
 - Improved :doc:`performance-unnecessary-copy-initialization
   <clang-tidy/checks/performance/unnecessary-copy-initialization>` by printing

clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp

@@ -54,6 +54,13 @@ void printf_deceptive_newline() {
   // CHECK-FIXES: std::println("Hello");
 }
 
+void printf_utf8_text() {
+  // Non-ASCII UTF-8 in format string should not crash.
+  printf("你好世界\n");
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+  // CHECK-FIXES: std::println("你好世界");
+}
+
 void printf_crlf_newline() {
   printf("Hello\r\n");
   // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::print' instead of 'printf' [modernize-use-std-print]
@@ -303,6 +310,13 @@ void fprintf_simple() {
   // CHECK-FIXES: std::print(stderr, "Hello");
 }
 
+void fprintf_utf8_text() {
+  // Non-ASCII UTF-8 in format string should not crash.
+  fprintf(stderr, "你好世界\n");
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+  // CHECK-FIXES: std::println(stderr, "你好世界");
+}
+
 void std_printf_simple() {
   std::printf("std::Hello");
   // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::print' instead of 'printf' [modernize-use-std-print]