Fix for PR9751 to change the behavior of -Wformat warnings. If the format

string is part of the function call, then there is no difference.  If the
format string is not, the warning will point to the call site and a note
will point to where the format string is.

Fix-it hints for strings are moved to the note if a note is emitted.  This will
prevent changes to format strings that may be used in multiple places.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143168 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 76 insertions, 0 deletions

diff --git a/test/Sema/format-strings.c b/test/Sema/format-strings.c
index 4f2ad99a57..c4bbc836d4 100644
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -393,3 +393,79 @@ void test_suppress_invalid_specifier() {
 #pragma clang diagnostic pop
 }
 
+// Make sure warnings are on for next test.
+#pragma GCC diagnostic warning "-Wformat"
+#pragma GCC diagnostic warning "-Wformat-security"
+
+// Test that the printf call site is where the warning is attached.  If the
+// format string is somewhere else, point to it in a note.
+void pr9751() {
+  const char kFormat1[] = "%d %d \n"; // expected-note{{format string is defined here}}}
+  printf(kFormat1, 0); // expected-warning{{more '%' conversions than data arguments}}
+  printf("%d %s\n", 0); // expected-warning{{more '%' conversions than data arguments}}
+
+  const char kFormat2[] = "%18$s\n"; // expected-note{{format string is defined here}}
+  printf(kFormat2, 1, "foo"); // expected-warning{{data argument position '18' exceeds the number of data arguments (2)}}
+  printf("%18$s\n", 1, "foo"); // expected-warning{{data argument position '18' exceeds the number of data arguments (2)}}
+
+  const char kFormat3[] = "%n"; // expected-note{{format string is defined here}}
+  printf(kFormat3, "as"); // expected-warning{{use of '%n' in format string discouraged}}
+  printf("%n", "as"); // expected-warning{{use of '%n' in format string discouraged}}
+
+  const char kFormat4[] = "%y"; // expected-note{{format string is defined here}}
+  printf(kFormat4, 5); // expected-warning{{invalid conversion specifier 'y'}}
+  printf("%y", 5); // expected-warning{{invalid conversion specifier 'y'}}
+
+  const char kFormat5[] = "%."; // expected-note{{format string is defined here}}
+  printf(kFormat5, 5); // expected-warning{{incomplete format specifier}}
+  printf("%.", 5); // expected-warning{{incomplete format specifier}}
+
+  const char kFormat6[] = "%s"; // expected-note{{format string is defined here}}
+  printf(kFormat6, 5); // expected-warning{{conversion specifies type 'char *' but the argument has type 'int'}}
+  printf("%s", 5); // expected-warning{{conversion specifies type 'char *' but the argument has type 'int'}}
+
+  const char kFormat7[] = "%0$"; // expected-note{{format string is defined here}}
+  printf(kFormat7, 5); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
+  printf("%0$", 5); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
+
+  const char kFormat8[] = "%1$d %d"; // expected-note{{format string is defined here}}
+  printf(kFormat8, 4, 4); // expected-warning{{cannot mix positional and non-positional arguments in format string}}
+  printf("%1$d %d", 4, 4); // expected-warning{{cannot mix positional and non-positional arguments in format string}}
+
+  const char kFormat9[] = ""; // expected-note{{format string is defined here}}
+  printf(kFormat9, 4, 4); // expected-warning{{format string is empty}}
+  printf("", 4, 4); // expected-warning{{format string is empty}}
+
+  const char kFormat10[] = "\0%d"; // expected-note{{format string is defined here}}
+  printf(kFormat10, 4); // expected-warning{{format string contains '\0' within the string body}}
+  printf("\0%d", 4); // expected-warning{{format string contains '\0' within the string body}}
+
+  const char kFormat11[] = "%*d"; // expected-note{{format string is defined here}}
+  printf(kFormat11); // expected-warning{{'*' specified field width is missing a matching 'int' argument}}
+  printf("%*d"); // expected-warning{{'*' specified field width is missing a matching 'int' argument}}
+
+  const char kFormat12[] = "%*d"; // expected-note{{format string is defined here}}
+  printf(kFormat12, 4.4); // expected-warning{{field width should have type 'int', but argument has type 'double'}}
+  printf("%*d", 4.4); // expected-warning{{field width should have type 'int', but argument has type 'double'}}
+
+  const char kFormat13[] = "%.3p"; // expected-note{{format string is defined here}}
+  void *p;
+  printf(kFormat13, p); // expected-warning{{precision used with 'p' conversion specifier, resulting in undefined behavior}}
+  printf("%.3p", p); // expected-warning{{precision used with 'p' conversion specifier, resulting in undefined behavior}}
+
+  const char kFormat14[] = "%0s"; // expected-note{{format string is defined here}}
+  printf(kFormat14, "a"); // expected-warning{{flag '0' results in undefined behavior with 's' conversion specifier}}
+  printf("%0s", "a"); // expected-warning{{flag '0' results in undefined behavior with 's' conversion specifier}}
+
+  const char kFormat15[] = "%hhs"; // expected-note{{format string is defined here}}
+  printf(kFormat15, "a"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
+  printf("%hhs", "a"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
+
+  const char kFormat16[] = "%-0d"; // expected-note{{format string is defined here}}
+  printf(kFormat16, 5); // expected-warning{{flag '0' is ignored when flag '-' is present}}
+  printf("%-0d", 5); // expected-warning{{flag '0' is ignored when flag '-' is present}}
+
+  // Make sure that the "format string is defined here" note is not emitted
+  // when the original string is within the argument expression.
+  printf(1 ? "yes %d" : "no %d"); // expected-warning 2{{more '%' conversions than data arguments}}
+}