[libc] Migrate ctype_utils to use char instead of int where applicable.

libc/src/__support/ctype_utils.h

@@ -27,7 +27,7 @@ namespace internal {
 // as well as a way to support non-ASCII character encodings.
 
 // Similarly, do not change these functions to use case ranges. e.g.
-//  bool islower(int ch) {
+//  bool islower(char ch) {
 //    switch(ch) {
 //    case 'a'...'z':
 //      return true;
@@ -37,7 +37,7 @@ namespace internal {
 // EBCDIC. Technically we could use some smaller ranges, but that's even harder
 // to read.
 
-LIBC_INLINE static constexpr bool islower(int ch) {
+LIBC_INLINE static constexpr bool islower(char ch) {
   switch (ch) {
   case 'a':
   case 'b':
@@ -71,7 +71,7 @@ LIBC_INLINE static constexpr bool islower(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr bool isupper(int ch) {
+LIBC_INLINE static constexpr bool isupper(char ch) {
   switch (ch) {
   case 'A':
   case 'B':
@@ -105,7 +105,7 @@ LIBC_INLINE static constexpr bool isupper(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr bool isdigit(int ch) {
+LIBC_INLINE static constexpr bool isdigit(char ch) {
   switch (ch) {
   case '0':
   case '1':
@@ -123,7 +123,7 @@ LIBC_INLINE static constexpr bool isdigit(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr int tolower(int ch) {
+LIBC_INLINE static constexpr char tolower(char ch) {
   switch (ch) {
   case 'A':
     return 'a';
@@ -182,7 +182,7 @@ LIBC_INLINE static constexpr int tolower(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr int toupper(int ch) {
+LIBC_INLINE static constexpr char toupper(char ch) {
   switch (ch) {
   case 'a':
     return 'A';
@@ -241,7 +241,7 @@ LIBC_INLINE static constexpr int toupper(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr bool isalpha(int ch) {
+LIBC_INLINE static constexpr bool isalpha(char ch) {
   switch (ch) {
   case 'a':
   case 'b':
@@ -301,7 +301,7 @@ LIBC_INLINE static constexpr bool isalpha(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr bool isalnum(int ch) {
+LIBC_INLINE static constexpr bool isalnum(char ch) {
   switch (ch) {
   case 'a':
   case 'b':
@@ -371,7 +371,7 @@ LIBC_INLINE static constexpr bool isalnum(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr int b36_char_to_int(int ch) {
+LIBC_INLINE static constexpr int b36_char_to_int(char ch) {
   switch (ch) {
   case '0':
     return 0;
@@ -476,7 +476,7 @@ LIBC_INLINE static constexpr int b36_char_to_int(int ch) {
   }
 }
 
-LIBC_INLINE static constexpr int int_to_b36_char(int num) {
+LIBC_INLINE static constexpr char int_to_b36_char(int num) {
   // Can't actually use LIBC_ASSERT here because it depends on integer_to_string
   // which depends on this.
 
@@ -559,7 +559,7 @@ LIBC_INLINE static constexpr int int_to_b36_char(int num) {
   }
 }
 
-LIBC_INLINE static constexpr bool isspace(int ch) {
+LIBC_INLINE static constexpr bool isspace(char ch) {
   switch (ch) {
   case ' ':
   case '\t':
@@ -574,7 +574,7 @@ LIBC_INLINE static constexpr bool isspace(int ch) {
 }
 
 // not yet encoding independent.
-LIBC_INLINE static constexpr bool isgraph(int ch) {
+LIBC_INLINE static constexpr bool isgraph(char ch) {
   return 0x20 < ch && ch < 0x7f;
 }
 

libc/src/__support/integer_to_string.h

@@ -378,9 +378,8 @@ template <typename T, typename Fmt = radix::Dec> class IntegerToString {
     using UNSIGNED_T = make_integral_or_big_int_unsigned_t<T>;
 
     LIBC_INLINE static char digit_char(uint8_t digit) {
-      const int result = internal::int_to_b36_char(digit);
-      return static_cast<char>(Fmt::IS_UPPERCASE ? internal::toupper(result)
-                                                 : result);
+      const char result = internal::int_to_b36_char(digit);
+      return Fmt::IS_UPPERCASE ? internal::toupper(result) : result;
     }
 
     LIBC_INLINE static void

libc/src/ctype/CMakeLists.txt

@@ -6,6 +6,7 @@ add_entrypoint_object(
     isalnum.h
   DEPENDS
     libc.include.ctype
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -16,6 +17,7 @@ add_entrypoint_object(
   HDRS
     isalpha.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -50,6 +52,7 @@ add_entrypoint_object(
   HDRS
     isdigit.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -60,6 +63,7 @@ add_entrypoint_object(
   HDRS
     isgraph.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -70,6 +74,7 @@ add_entrypoint_object(
   HDRS
     islower.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -88,6 +93,7 @@ add_entrypoint_object(
   HDRS
     ispunct.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -97,6 +103,9 @@ add_entrypoint_object(
     isspace.cpp
   HDRS
     isspace.h
+  DEPENDS
+    libc.src.__support.CPP.limits
+    libc.src.__support.ctype_utils
 )
 
 add_entrypoint_object(
@@ -106,6 +115,7 @@ add_entrypoint_object(
   HDRS
     isupper.h
   DEPENDS
+    libc.src.__support.CPP.limits  
     libc.src.__support.ctype_utils
 )
 
@@ -116,6 +126,7 @@ add_entrypoint_object(
   HDRS
     isxdigit.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -126,6 +137,7 @@ add_entrypoint_object(
   HDRS
     tolower.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -144,6 +156,7 @@ add_entrypoint_object(
   HDRS
     toupper.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
 )
 
@@ -160,6 +173,7 @@ add_entrypoint_object(
     isalnum_l.h
   DEPENDS
     libc.include.ctype
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -171,6 +185,7 @@ add_entrypoint_object(
   HDRS
     isalpha_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -202,6 +217,7 @@ add_entrypoint_object(
   HDRS
     isdigit_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -224,6 +240,7 @@ add_entrypoint_object(
   HDRS
     islower_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -257,6 +274,8 @@ add_entrypoint_object(
     isspace_l.h
   DEPENDS
     libc.hdr.types.locale_t
+    libc.src.__support.CPP.limits
+    libc.src.__support.ctype_utils
 )
 
 add_entrypoint_object(
@@ -266,6 +285,7 @@ add_entrypoint_object(
   HDRS
     isupper_l.h
   DEPENDS
+    libc.src.__support.CPP.limits  
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -277,6 +297,7 @@ add_entrypoint_object(
   HDRS
     isxdigit_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -288,6 +309,7 @@ add_entrypoint_object(
   HDRS
     tolower_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )
@@ -299,6 +321,7 @@ add_entrypoint_object(
   HDRS
     toupper_l.h
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.ctype_utils
     libc.hdr.types.locale_t
 )

libc/src/ctype/isalnum.cpp

@@ -7,15 +7,18 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/isalnum.h"
-#include "src/__support/ctype_utils.h"
 
+#include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
+#include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, isalnum, (int c)) {
-  return static_cast<int>(internal::isalnum(static_cast<unsigned>(c)));
+  if (c < 0 || c > cpp::numeric_limits<unsigned char>::max())
+    return 0;
+  return static_cast<int>(internal::isalnum(static_cast<char>(c)));
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/ctype/isalnum_l.cpp

@@ -7,15 +7,18 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/isalnum_l.h"
-#include "src/__support/ctype_utils.h"
 
+#include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
+#include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, isalnum_l, (int c, locale_t)) {
-  return static_cast<int>(internal::isalnum(static_cast<unsigned>(c)));
+  if (c < 0 || c > cpp::numeric_limits<unsigned char>::max())
+    return 0;
+  return static_cast<int>(internal::isalnum(static_cast<char>(c)));
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/ctype/isalpha.cpp

@@ -8,14 +8,17 @@
 
 #include "src/ctype/isalpha.h"
 
+#include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, isalpha, (int c)) {
-  return static_cast<int>(internal::isalpha(static_cast<unsigned>(c)));
+  if (c < 0 || c > cpp::numeric_limits<unsigned char>::max())
+    return 0;
+  return static_cast<int>(internal::isalpha(static_cast<char>(c)));
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/ctype/isalpha_l.cpp

@@ -8,14 +8,17 @@
 
 #include "src/ctype/isalpha_l.h"
 
+#include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, isalpha_l, (int c, locale_t)) {
-  return static_cast<int>(internal::isalpha(static_cast<unsigned>(c)));
+  if (c < 0 || c > cpp::numeric_limits<unsigned char>::max())
+    return 0;
+  return static_cast<int>(internal::isalpha(static_cast<char>(c)));
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/ctype/isdigit.cpp

@@ -7,14 +7,18 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/ctype/isdigit.h"
+
+#include "src/__support/CPP/limits.h"
 #include "src/__support/common.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(int, isdigit, (int c)) {
-  return static_cast<int>(internal::isdigit(static_cast<unsigned>(c)));
+  if (c < 0 || c > cpp::numeric_limits<unsigned char>::max())
+    return 0;
+  return static_cast<int>(internal::isdigit(static_cast<char>(c)));
 }
 
 } // namespace LIBC_NAMESPACE_DECL