[clang] Add getUnsignedPointerDiffType method

C11 standard refers to the unsigned counterpart of the type ptrdiff_t 
in the paragraph 7.21.6.1p7 where it defines the format specifier %tu.
In Clang (in PrintfFormatString.cpp, lines 508-510) there is a FIXME for this case,
in particular, Clang didn't diagnose %tu issues at all, i.e.
it didn't emit any warnings on the code printf("%tu", 3.14).
In this diff we add a method getUnsignedPointerDiffType for getting the corresponding type
similarly to how it's already done in the other analogous cases (size_t, ssize_t, ptrdiff_t etc)
and fix -Wformat diagnostics for %tu plus the emitted fix-it as well.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D38270

llvm-svn: 314470

1 files changed, 30 insertions, 0 deletions

diff --git a/clang/test/Sema/format-strings-scanf.c b/clang/test/Sema/format-strings-scanf.c
index e700d10618d..b7cdd7dd4a9 100644
--- a/clang/test/Sema/format-strings-scanf.c
+++ b/clang/test/Sema/format-strings-scanf.c
@@ -13,6 +13,16 @@ typedef __SIZE_TYPE__ size_t;
                       unsigned short : (short)0,                               \
                       unsigned char : (signed char)0))
 typedef __SSIZE_TYPE__ ssize_t;                         
+
+typedef __PTRDIFF_TYPE__ ptrdiff_t;
+#define __UNSIGNED_PTRDIFF_TYPE__                                              \
+  __typeof__(_Generic((__PTRDIFF_TYPE__)0,                                     \
+                      long long int : (unsigned long long int)0,               \
+                      long int : (unsigned long int)0,                         \
+                      int : (unsigned int)0,                                   \
+                      short : (unsigned short)0,                               \
+                      signed char : (unsigned char)0))
+
 typedef struct _FILE FILE;
 typedef __WCHAR_TYPE__ wchar_t;
 
@@ -200,6 +210,26 @@ void test_size_types() {
   scanf("%zn", &d3); // expected-warning-re{{format specifies type 'ssize_t *' (aka '{{.+}}') but the argument has type 'double *'}}
 }
 
+void test_ptrdiff_t_types() {
+  __UNSIGNED_PTRDIFF_TYPE__ p1 = 0;
+  scanf("%tu", &p1); // No warning.
+
+  double d1 = 0.;
+  scanf("%tu", &d1); // expected-warning-re{{format specifies type 'unsigned ptrdiff_t *' (aka '{{.+}}') but the argument has type 'double *'}}
+
+  ptrdiff_t p2 = 0;
+  scanf("%td", &p2); // No warning.
+  
+  double d2 = 0.;
+  scanf("%td", &d2); // expected-warning-re{{format specifies type 'ptrdiff_t *' (aka '{{.+}}') but the argument has type 'double *'}}
+
+  ptrdiff_t p3 = 0;
+  scanf("%tn", &p3); // No warning.
+  
+  double d3 = 0.;
+  scanf("%tn", &d3); // expected-warning-re{{format specifies type 'ptrdiff_t *' (aka '{{.+}}') but the argument has type 'double *'}}
+}
+
 void check_conditional_literal(char *s, int *i) {
   scanf(0 ? "%s" : "%d", i); // no warning
   scanf(1 ? "%s" : "%d", i); // expected-warning{{format specifies type 'char *'}}