Fix incorrect warning with %zi in format string (#3437)

Author: FabianWolff

lib/checkio.cpp

@@ -1782,7 +1782,7 @@ void CheckIO::invalidScanfArgTypeError_int(const Token* tok, nonneg int numForma
         else
             errmsg << "intmax_t";
     } else if (specifier[0] == 'z') {
-        if (specifier[1] == 'd')
+        if (specifier[1] == 'd' || specifier[1] == 'i')
             errmsg << "ssize_t";
         else
             errmsg << "size_t";
@@ -1875,7 +1875,7 @@ static void printfFormatType(std::ostream& os, const std::string& specifier, boo
         else
             os << "intmax_t";
     } else if (specifier[0] == 'z') {
-        if (specifier[1] == 'd')
+        if (specifier[1] == 'd' || specifier[1] == 'i')
             os << "ssize_t";
         else
             os << "size_t";

test/testio.cpp

@@ -1533,6 +1533,8 @@ class TestIO : public TestFixture {
         TEST_SCANF_NOWARN("%zd", "ssize_t", "ssize_t");
         TEST_SCANF_WARN_AKA("%zd", "ssize_t", "ptrdiff_t", "signed long", "signed long long");
 
+        TEST_SCANF_WARN_AKA("%zi", "ssize_t", "size_t", "unsigned long", "unsigned long long");
+
         TEST_SCANF_WARN("%tu", "unsigned ptrdiff_t", "bool");
         TEST_SCANF_WARN("%tu", "unsigned ptrdiff_t", "char");
         TEST_SCANF_WARN("%tu", "unsigned ptrdiff_t", "signed char");
@@ -3705,6 +3707,9 @@ class TestIO : public TestFixture {
         TEST_PRINTF_WARN_AKA("%jx", "uintmax_t", "std::intptr_t", "signed long", "signed long long");
         TEST_PRINTF_WARN_AKA("%jx", "uintmax_t", "std::uintptr_t", "unsigned long", "unsigned long long");
 
+        TEST_PRINTF_WARN_AKA("%zd", "ssize_t", "size_t", "unsigned long", "unsigned long long");
+        TEST_PRINTF_WARN_AKA("%zi", "ssize_t", "size_t", "unsigned long", "unsigned long long");
+
         TEST_PRINTF_WARN("%zu", "size_t", "bool");
         TEST_PRINTF_WARN("%zu", "size_t", "char");
         TEST_PRINTF_WARN("%zu", "size_t", "signed char");