Enable -Wformat and -Wformat-security by default.


--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -412,7 +412,7 @@ C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning LangEnabledBy(C ObjC C++ O
 Warn about format strings that are not literals
 
 Wformat-security
-C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
+C ObjC C++ ObjC++ Var(warn_format_security) Init(1) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
 Warn about possible security problems with format functions
 
 Wformat-y2k
@@ -424,7 +424,7 @@ C ObjC C++ ObjC++ Var(warn_format_zero_length) Warning LangEnabledBy(C ObjC C++
 Warn about zero-length formats
 
 Wformat=
-C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_format) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0)
+C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_format) Init(1) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0)
 Warn about printf/scanf/strftime/strfmon format string anomalies
 
 Wignored-qualifiers
--- a/gcc/doc/gcc.info
+++ b/gcc/doc/gcc.info
@@ -3451,6 +3451,8 @@ compiler warns that an unrecognized option is present.
           '-Wno-format-contains-nul', '-Wno-format-extra-args', and
           '-Wno-format-zero-length'.  '-Wformat' is enabled by '-Wall'.
 
+          This option is enabled by default in Alpine Linux.
+
      '-Wno-format-contains-nul'
           If '-Wformat' is specified, do not warn about format strings
           that contain NUL bytes.
@@ -3496,6 +3498,8 @@ compiler warns that an unrecognized option is present.
           future warnings may be added to '-Wformat-security' that are
           not included in '-Wformat-nonliteral'.)
 
+          This option is enabled by default in Alpine Linux.
+
      '-Wformat-y2k'
           If '-Wformat' is specified, also warn about 'strftime' formats
           that may yield only a two-digit year.