[clang-tidy] Fix modernize-use-std-print/format for fmt (#99021)

When fixing #92896 in 0e62d5c (#94104)
I failed to spot that I'd broken converting from fmt::printf,
fmt::fprintf and fmt::sprintf in these checks since the format parameter
of those functions is not a simple character pointer.

The first part of the previous fix to avoid the assert and instead
produce an error message was sufficient. It was only the second part
that required the format parameter of the called function to be a simple
character pointer that was problematic. Let's remove that second part
and add the now-expected error messages to the lit tests along with
fixing the prototype for the fmt functions to more accurately reflect
the ones used by the fmt library so they are actually useful.

Fixes #92896

Author: mikecrowe

clang-tools-extra/clang-tidy/modernize/UseStdFormatCheck.cpp

@@ -47,15 +47,13 @@ void UseStdFormatCheck::registerPPCallbacks(const SourceManager &SM,
 }
 
 void UseStdFormatCheck::registerMatchers(MatchFinder *Finder) {
-  auto CharPointerType =
-      hasType(pointerType(pointee(matchers::isSimpleChar())));
   Finder->addMatcher(
-      callExpr(
-          argumentCountAtLeast(1), hasArgument(0, stringLiteral(isOrdinary())),
-          callee(functionDecl(
-                     unless(cxxMethodDecl()), hasParameter(0, CharPointerType),
-                     matchers::matchesAnyListedName(StrFormatLikeFunctions))
-                     .bind("func_decl")))
+      callExpr(argumentCountAtLeast(1),
+               hasArgument(0, stringLiteral(isOrdinary())),
+               callee(functionDecl(unless(cxxMethodDecl()),
+                                   matchers::matchesAnyListedName(
+                                       StrFormatLikeFunctions))
+                          .bind("func_decl")))
           .bind("strformat"),
       this);
 }

clang-tools-extra/clang-tidy/modernize/UseStdPrintCheck.cpp

@@ -95,15 +95,12 @@ unusedReturnValue(clang::ast_matchers::StatementMatcher MatchedCallExpr) {
 }
 
 void UseStdPrintCheck::registerMatchers(MatchFinder *Finder) {
-  auto CharPointerType =
-      hasType(pointerType(pointee(matchers::isSimpleChar())));
   if (!PrintfLikeFunctions.empty())
     Finder->addMatcher(
         unusedReturnValue(
             callExpr(argumentCountAtLeast(1),
                      hasArgument(0, stringLiteral(isOrdinary())),
                      callee(functionDecl(unless(cxxMethodDecl()),
-                                         hasParameter(0, CharPointerType),
                                          matchers::matchesAnyListedName(
                                              PrintfLikeFunctions))
                                 .bind("func_decl")))
@@ -116,7 +113,6 @@ void UseStdPrintCheck::registerMatchers(MatchFinder *Finder) {
             callExpr(argumentCountAtLeast(2),
                      hasArgument(1, stringLiteral(isOrdinary())),
                      callee(functionDecl(unless(cxxMethodDecl()),
-                                         hasParameter(1, CharPointerType),
                                          matchers::matchesAnyListedName(
                                              FprintfLikeFunctions))
                                 .bind("func_decl")))

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

@@ -63,4 +63,5 @@ std::string unsupported_format_parameter_type()
   // No fixes here because the format parameter of the function called is not a
   // string.
   return bad_format_type_strprintf("");
+// CHECK-MESSAGES: [[@LINE-1]]:10: warning: unable to use 'fmt::format' instead of 'bad_format_type_strprintf' because first argument is not a narrow string literal [modernize-use-std-format]
 }

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

@@ -12,9 +12,9 @@
 
 namespace fmt
 {
-// Use const char * for the format since the real type is hard to mock up.
-template <typename... Args>
-std::string sprintf(const char *format, const Args&... args);
+template <typename S, typename... T,
+          typename Char = char>
+std::basic_string<Char> sprintf(const S& fmt, const T&... args);
 } // namespace fmt
 
 std::string fmt_sprintf_simple() {

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

@@ -1,8 +1,8 @@
 // RUN: %check_clang_tidy -std=c++23 %s modernize-use-std-print %t -- \
 // RUN:   -config="{CheckOptions: \
 // RUN:             { \
-// RUN:               modernize-use-std-print.PrintfLikeFunctions: 'unqualified_printf;::myprintf; mynamespace::myprintf2; bad_format_type_printf', \
-// RUN:               modernize-use-std-print.FprintfLikeFunctions: '::myfprintf; mynamespace::myfprintf2; bad_format_type_fprintf' \
+// RUN:               modernize-use-std-print.PrintfLikeFunctions: 'unqualified_printf;::myprintf; mynamespace::myprintf2; bad_format_type_printf; fmt::printf', \
+// RUN:               modernize-use-std-print.FprintfLikeFunctions: '::myfprintf; mynamespace::myfprintf2; bad_format_type_fprintf; fmt::fprintf' \
 // RUN:             } \
 // RUN:            }" \
 // RUN:   -- -isystem %clang_tidy_headers
@@ -106,5 +106,27 @@ void unsupported_format_parameter_type()
   // No fixes here because the format parameter of the function called is not a
   // string.
   bad_format_type_printf("Hello %s", "world");
+// CHECK-MESSAGES: [[@LINE-1]]:3: warning: unable to use 'std::print' instead of 'bad_format_type_printf' because first argument is not a narrow string literal [modernize-use-std-print]
+
   bad_format_type_fprintf(stderr, "Hello %s", "world");
+// CHECK-MESSAGES: [[@LINE-1]]:3: warning: unable to use 'std::print' instead of 'bad_format_type_fprintf' because first argument is not a narrow string literal [modernize-use-std-print]
+}
+
+namespace fmt {
+  template <typename S, typename... T>
+  inline int printf(const S& fmt, const T&... args);
+
+  template <typename S, typename... T>
+  inline int fprintf(std::FILE* f, const S& fmt, const T&... args);
+}
+
+void fmt_printf()
+{
+  fmt::printf("fmt::printf templated %s argument %d\n", "format", 424);
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::println' instead of 'printf' [modernize-use-std-print]
+  // CHECK-FIXES: std::println("fmt::printf templated {} argument {}", "format", 424);
+
+  fmt::fprintf(stderr, "fmt::fprintf templated %s argument %d\n", "format", 425);
+  // CHECK-MESSAGES: [[@LINE-1]]:3: warning: use 'std::println' instead of 'fprintf' [modernize-use-std-print]
+  // CHECK-FIXES: std::println(stderr, "fmt::fprintf templated {} argument {}", "format", 425);
 }