[clang-tools-extra] [clang-tidy] Add modernize-use-std-format check (PR #90397)

[Mike Crowe via cfe-commits]

================
@@ -0,0 +1,97 @@
+// RUN: %check_clang_tidy \
+// RUN:   -std=c++20 %s modernize-use-std-format %t -- \
+// RUN:   -config="{CheckOptions: [{key: StrictMode, value: true}]}" \
+// RUN:   -- -isystem %clang_tidy_headers
+// RUN: %check_clang_tidy \
+// RUN:   -std=c++20 %s modernize-use-std-format %t -- \
+// RUN:   -config="{CheckOptions: [{key: StrictMode, value: false}]}" \
+// RUN:   -- -isystem %clang_tidy_headers
+#include <string>
+// CHECK-FIXES: #include <format>
+
+namespace absl
+{
+// Use const char * for the format since the real type is hard to mock up.
+template <typename... Args>
+std::string StrFormat(const char *format, const Args&... args);
+} // namespace absl
+
+template <typename T>
+struct iterator {
+  T *operator->();
+  T &operator*();
+};
+
+std::string StrFormat_simple() {
+  return absl::StrFormat("Hello");
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("Hello");
+}
+
+std::string StrFormat_complex(const char *name, double value) {
+  return absl::StrFormat("'%s'='%f'", name, value);
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("'{}'='{:f}'", name, value);
+}
+
+std::string StrFormat_integer_conversions() {
+  return absl::StrFormat("int:%d int:%d char:%c char:%c", 65, 'A', 66, 'B');
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("int:{} int:{:d} char:{:c} char:{}", 65, 'A', 66, 'B');
+}
+
+// FormatConverter is capable of removing newlines from the end of the format
+// string. Ensure that isn't incorrectly happening for std::format.
+std::string StrFormat_no_newline_removal() {
+  return absl::StrFormat("a line\n");
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("a line\n");
+}
+
+// FormatConverter is capable of removing newlines from the end of the format
+// string. Ensure that isn't incorrectly happening for std::format.
+std::string StrFormat_cstr_removal(const std::string &s1, const std::string *s2) {
+  return absl::StrFormat("%s %s %s %s", s1.c_str(), s1.data(), s2->c_str(), s2->data());
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("{} {} {} {}", s1, s1, *s2, *s2);
+}
+
+std::string StrFormat_strict_conversion() {
+  const unsigned char uc = 'A';
+  return absl::StrFormat("Integer %hhd from unsigned char\n", uc);
+  // CHECK-MESSAGES: [[@LINE-1]]:10: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: return std::format("Integer {} from unsigned char\n", uc);
+}
+
+std::string StrFormat_field_width_and_precision() {
+  auto s1 = absl::StrFormat("width only:%*d width and precision:%*.*f precision only:%.*f", 3, 42, 4, 2, 3.14159265358979323846, 5, 2.718);
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: std::format("width only:{:{}} width and precision:{:{}.{}f} precision only:{:.{}f}", 42, 3, 3.14159265358979323846, 4, 2, 2.718, 5);
+
+  auto s2 = absl::StrFormat("width and precision positional:%1$*2$.*3$f after", 3.14159265358979323846, 4, 2);
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: std::format("width and precision positional:{0:{1}.{2}f} after", 3.14159265358979323846, 4, 2);
+
+  const int width = 10, precision = 3;
+  const unsigned int ui1 = 42, ui2 = 43, ui3 = 44;
+  auto s3 = absl::StrFormat("casts width only:%*d width and precision:%*.*d precision only:%.*d\n", 3, ui1, 4, 2, ui2, 5, ui3);
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES-NOTSTRICT: std::format("casts width only:{:{}} width and precision:{:{}.{}} precision only:{:.{}}", ui1, 3, ui2, 4, 2, ui3, 5);
+  // CHECK-FIXES-STRICT: std::format("casts width only:{:{}} width and precision:{:{}.{}} precision only:{:.{}}", static_cast<int>(ui1), 3, static_cast<int>(ui2), 4, 2, static_cast<int>(ui3), 5);
+
+  auto s4 = absl::StrFormat("c_str removal width only:%*s width and precision:%*.*s precision only:%.*s", 3, s1.c_str(), 4, 2, s2.c_str(), 5, s3.c_str());
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: std::format("c_str removal width only:{:>{}} width and precision:{:>{}.{}} precision only:{:.{}}", s1, 3, s2, 4, 2, s3, 5);
+
+  const std::string *ps1 = &s1, *ps2 = &s2, *ps3 = &s3;
+  auto s5 = absl::StrFormat("c_str() removal pointer width only:%-*s width and precision:%-*.*s precision only:%-.*s", 3, ps1->c_str(), 4, 2, ps2->c_str(), 5, ps3->c_str());
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: std::format("c_str() removal pointer width only:{:{}} width and precision:{:{}.{}} precision only:{:.{}}", *ps1, 3, *ps2, 4, 2, *ps3, 5);
+
+  iterator<std::string> is1, is2, is3;
+  auto s6 = absl::StrFormat("c_str() removal iterator width only:%-*s width and precision:%-*.*s precision only:%-.*s", 3, is1->c_str(), 4, 2, is2->c_str(), 5, is3->c_str());
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: use 'std::format' instead of 'StrFormat' [modernize-use-std-format]
+  // CHECK-FIXES: std::format("c_str() removal iterator width only:{:{}} width and precision:{:{}.{}} precision only:{:.{}}", *is1, 3, *is2, 4, 2, *is3, 5);
+
+  return s1 + s2 + s3 + s4 + s5 + s6;
+}
----------------
mikecrowe wrote:

https://github.com/llvm/llvm-project/blob/84a81343cdda86efa34a9340f2a7ab7d2b388731/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-format.cpp#L99

@PiotrZSL, were these the kinds of tests you were expecting when you made your request and are you happy with the behaviour of the check for them? If not, please can you provide more specific advice?


https://github.com/llvm/llvm-project/pull/90397