[clang] [clang] Catch missing format attributes (PR #105479)

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,174 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,beforeCxx2b -Wmissing-format-attribute %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2b -Wmissing-format-attribute %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++23 -Wmissing-format-attribute %s
+// RUN: not %clang_cc1 -fsyntax-only -Wmissing-format-attribute -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+typedef __SIZE_TYPE__ size_t;
+typedef __builtin_va_list va_list;
+
+namespace std
+{
+    template<class Elem> struct basic_string_view {};
+    template<class Elem> struct basic_string {
+        const Elem *c_str() const noexcept;
+        basic_string(const basic_string_view<Elem> SW);
+    };
+
+    using string = basic_string<char>;
+    using wstring = basic_string<wchar_t>;
+    using string_view = basic_string_view<char>;
+    using wstring_view = basic_string_view<wchar_t>;
+}
+
+__attribute__((__format__(__printf__, 1, 2)))
+int printf(const char *, ...); // #printf
+
+__attribute__((__format__(__scanf__, 1, 2)))
+int scanf(const char *, ...); // #scanf
+
+__attribute__((__format__(__printf__, 1, 0)))
+int vprintf(const char *, va_list); // #vprintf
+
+__attribute__((__format__(__scanf__, 1, 0)))
+int vscanf(const char *, va_list); // #vscanf
+
+__attribute__((__format__(__printf__, 2, 0)))
+int vsprintf(char *, const char *, va_list); // #vsprintf
+
+__attribute__((__format__(__printf__, 3, 0)))
+int vsnprintf(char *ch, size_t, const char *, va_list); // #vsnprintf
+
+void f1(const std::string &str, ... /* args */) // #f1
+{
+    va_list args;
+    vscanf(str.c_str(), args); // expected-no-warning@#f1
+}
+
+__attribute__((format(printf, 1, 2))) // expected-error {{format argument not a string type}}
+void f2(const std::string &str, ... /* args */); // #f2
+
+void f3(std::string_view str, ... /* args */) // #f3
+{
+    va_list args;
+    vscanf(std::string(str).c_str(), args); // expected-no-warning@#f3
+}
+
+__attribute__((format(printf, 1, 2))) // expected-error {{format argument not a string type}}
+void f4(std::string_view str, ... /* args */); // #f4
+
+void f5(const std::wstring &str, ... /* args */) // #f5
+{
+    va_list args;
+    vprintf((const char *)str.c_str(), args); // expected-no-warning@#f5
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AaronBallman wrote:

Use `vwprintf` instead of casting.

https://github.com/llvm/llvm-project/pull/105479