[clang] [llvm] [Sema] Implement support for -Wformat-signedness (PR #74440)

[Yingchi Long via cfe-commits]

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@@ -0,0 +1,107 @@
+// RUN: %clang_cc1 -std=c11 -fsyntax-only -verify -Wformat -Wformat-signedness %s
+
+int printf(const char *restrict format, ...);
+int scanf(const char * restrict, ...);
+
+void test_printf_bool(_Bool x)
+{
+    printf("%d", x); // no-warning
+    printf("%u", x); // expected-warning{{format specifies type 'unsigned int' but the argument has type '_Bool'}}
+    printf("%x", x); // expected-warning{{format specifies type 'unsigned int' but the argument has type '_Bool'}}
+}
+
+void test_printf_char(char x)
+{
+    printf("%c", x); // no-warning
+}
+
+void test_printf_unsigned_char(unsigned char x)
+{
+    printf("%c", x); // no-warning
+}
+
+void test_printf_int(int x)
+{
+    printf("%d", x); // no-warning
+    printf("%u", x); // expected-warning{{format specifies type 'unsigned int' but the argument has type 'int'}}
+    printf("%x", x); // expected-warning{{format specifies type 'unsigned int' but the argument has type 'int'}}
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inclyc wrote:

will this be a little pedantic?

https://github.com/llvm/llvm-project/pull/74440