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

[Aaron Ballman via cfe-commits]

================
@@ -0,0 +1,393 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,c_diagnostics -Wmissing-format-attribute %s
+// RUN: %clang_cc1 -fsyntax-only -Wmissing-format-attribute -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s --check-prefixes=CHECK,C-CHECK
+// RUN: %clang_cc1 -fsyntax-only -x c++ -verify=expected,cpp_diagnostics -Wmissing-format-attribute %s
+// RUN: %clang_cc1 -fsyntax-only -x c++ -verify=expected,cpp_diagnostics -std=c++2b -Wmissing-format-attribute %s
+// RUN: %clang_cc1 -fsyntax-only -x c++ -verify=expected,cpp_diagnostics -std=c++23 -Wmissing-format-attribute %s
+// RUN: not %clang_cc1 -fsyntax-only -x c++ -Wmissing-format-attribute -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+#ifndef __cplusplus
+typedef __CHAR16_TYPE__ char16_t;
+typedef __CHAR32_TYPE__ char32_t;
+typedef __WCHAR_TYPE__ wchar_t;
+#endif
+
+typedef __SIZE_TYPE__ size_t;
+typedef __builtin_va_list va_list;
+
+__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
+
+__attribute__((__format__(__scanf__, 1, 4)))
+void f1(char *out, const size_t len, const char *format, ... /* args */) // #f1
+{
+    va_list args;
+    vsnprintf(out, len, format, args); // expected-no-warning@#f1
+}
+
+__attribute__((__format__(__printf__, 1, 4)))
+void f2(char *out, const size_t len, const char *format, ... /* args */) // #f2
+{
+    va_list args;
+    vsnprintf(out, len, format, args); // expected-warning@#f2 {{diagnostic behavior may be improved by adding the 'printf' format attribute to the declaration of 'f2'}}
+                                       // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:6-[[@LINE-4]]:6}:"__attribute__((format(printf, 3, 4)))"
+}
+
+void f3(char *out, va_list args) // #f3
+{
+    vprintf(out, args); // expected-warning@#f3 {{diagnostic behavior may be improved by adding the 'printf' format attribute to the declaration of 'f3'}}
+                        // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:6-[[@LINE-3]]:6}:"__attribute__((format(printf, 1, 0)))"
+}
+
+void f4(char* out, ... /* args */) // #f4
+{
+    va_list args;
+    vprintf("test", args); // expected-no-warning@#f4
+
+    const char *ch;
+    vprintf(ch, args); // expected-no-warning@#f4
+}
+
+void f5(va_list args) // #f5
+{
+    char *ch;
+    vscanf(ch, args); // expected-no-warning@#f5
+}
+
+void f6(char *out, va_list args) // #f6
+{
+    char *ch;
+    vprintf(ch, args); // expected-no-warning@#f6
+    vprintf("test", args); // expected-no-warning@#f6
+    vprintf(out, args); // expected-warning@#f6 {{diagnostic behavior may be improved by adding the 'printf' format attribute to the declaration of 'f6'}}
+                        // CHECK: fix-it:"{{.*}}":{[[@LINE-6]]:6-[[@LINE-6]]:6}:"__attribute__((format(printf, 1, 0)))"
+}
+
+void f7(const char *out, ... /* args */) // #f7
+{
+    va_list args;
+
+    vscanf(out, args); // expected-warning@#f7 {{diagnostic behavior may be improved by adding the 'scanf' format attribute to the declaration of 'f7'}}
+                       // CHECK: fix-it:"{{.*}}":{[[@LINE-5]]:6-[[@LINE-5]]:6}:"__attribute__((format(scanf, 1, 2)))"
+}
+
+void f8(const char *out, ... /* args */) // #f8
+{
+    va_list args;
+
+    vscanf(out, args); // expected-no-warning@#f8
+    vprintf(out, args); // expected-no-warning@#f8
+}
+
+void f9(const char out[], ... /* args */) // #f9
+{
+    va_list args;
+    char *ch;
+    vprintf(ch, args); // expected-no-warning
+    vsprintf(ch, out, args); // expected-warning@#f9 {{diagnostic behavior may be improved by adding the 'printf' format attribute to the declaration of 'f9'}}
+                             // CHECK: fix-it:"{{.*}}":{[[@LINE-6]]:6-[[@LINE-6]]:6}:"__attribute__((format(printf, 1, 2)))"
+}
+
+void f10(const wchar_t *out, ... /* args */) // #f10
+{
+    va_list args;
+    vscanf(out, args);
+#if (defined(__aarch64__) && !defined(_WIN64)) || (defined(__arm__) && !defined(_WIN32))
+                        // c_diagnostics-warning at -2 {{incompatible pointer types passing 'const wchar_t *' (aka 'const unsigned int *') to parameter of type 'const char *'}}
+#elif __SIZEOF_WCHAR_T__ == 4
+                        // c_diagnostics-warning at -4 {{incompatible pointer types passing 'const wchar_t *' (aka 'const int *') to parameter of type 'const char *'}}
+#else
+                        // c_diagnostics-warning at -6 {{incompatible pointer types passing 'const wchar_t *' (aka 'const unsigned short *') to parameter of type 'const char *'}}
+#endif
+                        // c_diagnostics-note@#vscanf {{passing argument to parameter here}}
+                        // c_diagnostics-warning@#f10 {{diagnostic behavior may be improved by adding the 'scanf' format attribute to the declaration of 'f10'}}
+                        // C-CHECK: fix-it:"{{.*}}":{[[@LINE-13]]:6-[[@LINE-13]]:6}:"__attribute__((format(scanf, 1, 2)))"
+                        // cpp_diagnostics-error at -11 {{no matching function for call to 'vscanf'}}
+                        // cpp_diagnostics-note@#vscanf {{candidate function not viable: no known conversion from 'const wchar_t *' to 'const char *' for 1st argument}}
+}
+
+void f11(const wchar_t *out, ... /* args */) // #f11
+{
+    va_list args;
+    vscanf((const char *) out, args); // expected-warning@#f11 {{diagnostic behavior may be improved by adding the 'scanf' format attribute to the declaration of 'f11'}}
+                                      // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:6-[[@LINE-4]]:6}:"__attribute__((format(scanf, 1, 2)))"
+}
+
+void f12(const wchar_t *out, ... /* args */) // #f12
+{
+    va_list args;
+    vscanf((char *) out, args); // expected-warning@#f12 {{diagnostic behavior may be improved by adding the 'scanf' format attribute to the declaration of 'f12'}}
----------------
AaronBallman wrote:

Here too.

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