Default the integer value limits to 128 bits when __int128 extensions are allowed. [GH edgcpp#38]

Author: mohitmishra786

cmake/macro-conf/support/platform/linux/base.cmakedef

@@ -42,9 +42,6 @@ LONG_LONG_ALLOWED=1
 INTEGER_VALUE_REPR_IS_A_HOST_INTEGER=0
 TYPE_FOR_AN_INTEGER_VALUE=unsigned long long
 TYPE_FOR_A_SIGNED_INTEGER_VALUE=long long
-MAX_INTEGER_VALUE=9223372036854775807LL
-MIN_INTEGER_VALUE=(-MAX_INTEGER_VALUE-1)
-MAX_UNSIGNED_INTEGER_VALUE=18446744073709551615ULL
 FP_LONG_DOUBLE_IS_80BIT_EXTENDED=1
 LINKER_CAN_DISCARD_DUPLICATE_DEFINITIONS=1
 

src/Changes

@@ -12,6 +12,22 @@ ref-qualifiers.  They now leave such types unchanged.  For example, with
   using F = __add_pointer(F);  // Previously a spurious error, now okay.
 
 
+10/20/26 [GH #38]
+Integer value limits for a 128-bit host integer representation
+
+When INTEGER_VALUE_REPR_IS_A_HOST_INTEGER is TRUE and __int128 extensions are
+allowed, the integer value types default to the 128-bit types, but
+MAX_INTEGER_VALUE, MIN_INTEGER_VALUE, and MAX_UNSIGNED_INTEGER_VALUE still
+defaulted to 64-bit limits.  As a result, constant arithmetic on __int128
+values that did not fit in 64 bits could be wrongly diagnosed as overflowing.
+For example, with --gnu_version 150200:
+
+  constexpr __int128 s = (__int128)1 << 100;
+  static_assert(s * 4 == ((__int128)1 << 102), "");  // Previously an error.
+
+This is now fixed.
+
+
 10/20/26 [GH #173]
 CTAD through a template template parameter of an alias template
 

src/defines_linux.h

@@ -282,9 +282,6 @@ Linux.
 #ifndef TYPE_FOR_A_SIGNED_INTEGER_VALUE
 #define TYPE_FOR_A_SIGNED_INTEGER_VALUE long long
 #endif /* TYPE_FOR_A_SIGNED_INTEGER_VALUE */
-#define MAX_INTEGER_VALUE 9223372036854775807LL
-#define MIN_INTEGER_VALUE (-MAX_INTEGER_VALUE-1)
-#define MAX_UNSIGNED_INTEGER_VALUE 18446744073709551615ULL
 
 #if defined(__aarch64__) || defined(__riscv)
 /* 64-bit ARM and RISC-V use a 128-bit long double representation. */

src/targ_def.h

@@ -1536,6 +1536,9 @@ typedef TYPE_FOR_A_SIGNED_INTEGER_VALUE a_signed_integer_value;
 
 /* Minimum and maximum values that can be represented in an_integer_value. */
 #ifndef MAX_INTEGER_VALUE
+#if INT128_EXTENSIONS_ALLOWED
+#define MAX_INTEGER_VALUE ((__int128_t)(~(__uint128_t)0 >> 1))
+#else /* !INT128_EXTENSIONS_ALLOWED */
 #if LONG_LONG_ALLOWED
 #ifdef LLONG_MAX
 #define MAX_INTEGER_VALUE LLONG_MAX
@@ -1545,8 +1548,12 @@ typedef TYPE_FOR_A_SIGNED_INTEGER_VALUE a_signed_integer_value;
 #else /* !LONG_LONG_ALLOWED */
 #define MAX_INTEGER_VALUE LONG_MAX
 #endif /* LONG_LONG_ALLOWED */
+#endif /* INT128_EXTENSIONS_ALLOWED */
 #endif /* ifndef MAX_INTEGER_VALUE */
 #ifndef MIN_INTEGER_VALUE
+#if INT128_EXTENSIONS_ALLOWED
+#define MIN_INTEGER_VALUE (-MAX_INTEGER_VALUE-1)
+#else /* !INT128_EXTENSIONS_ALLOWED */
 #if LONG_LONG_ALLOWED
 #if defined(LLONG_MIN) && LLONG_MIN < LLONG_MAX /*lint !e30*/
 /* The preceding condition detects an incorrect definition of LLONG_MIN
@@ -1558,8 +1565,12 @@ typedef TYPE_FOR_A_SIGNED_INTEGER_VALUE a_signed_integer_value;
 #else /* !LONG_LONG_ALLOWED */
 #define MIN_INTEGER_VALUE LONG_MIN
 #endif /* LONG_LONG_ALLOWED */
+#endif /* INT128_EXTENSIONS_ALLOWED */
 #endif /* ifndef MIN_INTEGER_VALUE */
 #ifndef MAX_UNSIGNED_INTEGER_VALUE
+#if INT128_EXTENSIONS_ALLOWED
+#define MAX_UNSIGNED_INTEGER_VALUE (~(__uint128_t)0)
+#else /* !INT128_EXTENSIONS_ALLOWED */
 #if LONG_LONG_ALLOWED
 #ifdef ULLONG_MAX
 #define MAX_UNSIGNED_INTEGER_VALUE ULLONG_MAX
@@ -1569,6 +1580,7 @@ typedef TYPE_FOR_A_SIGNED_INTEGER_VALUE a_signed_integer_value;
 #else /* !LONG_LONG_ALLOWED */
 #define MAX_UNSIGNED_INTEGER_VALUE ULONG_MAX
 #endif /* LONG_LONG_ALLOWED */
+#endif /* INT128_EXTENSIONS_ALLOWED */
 #endif /* ifndef MAX_UNSIGNED_INTEGER_VALUE */
 #ifndef BITS_IN_AN_INTEGER_VALUE
 #define BITS_IN_AN_INTEGER_VALUE (sizeof(an_integer_value) * CHAR_BIT)

tests/expectations/edg_x86_32/changes.log

@@ -7,3 +7,4 @@ EDGcpfe28436.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[6.8] GNU/clang compatibility: larg
 EDGcpfe28794.sft.cpp:fp:-DTEST_NUMBER=1:REQUIREMENTS NOT MET:Abort on __builtin_bit_cast in dependent context
 EDGcpfe8330.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[4.1] Microsoft compatibility: Calling conventions and pointer-to-member-function
 EDGcpfe9522.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[4.1] Microsoft compatibility: __ptr64 on 64-bit targets
+GH38.sft.cpp:fn:-DTEST_NUMBER=1 --gnu_version 150200:REQUIREMENTS NOT MET:[GH #38] Integer value limits for a 128-bit host integer representation

tests/expectations/edg_x86_32_cp/changes.log

@@ -13,3 +13,4 @@ EDGcpfe28436.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[6.8] GNU/clang compatibility: larg
 EDGcpfe28794.sft.cpp:fp:-DTEST_NUMBER=1:REQUIREMENTS NOT MET:Abort on __builtin_bit_cast in dependent context
 EDGcpfe8330.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[4.1] Microsoft compatibility: Calling conventions and pointer-to-member-function
 EDGcpfe9522.sft.cpp:fp:-DTEST_NUMBER=1:FAIL:[4.1] Microsoft compatibility: __ptr64 on 64-bit targets
+GH38.sft.cpp:fn:-DTEST_NUMBER=1 --gnu_version 150200:REQUIREMENTS NOT MET:[GH #38] Integer value limits for a 128-bit host integer representation

tests/tests/changes/.GH38.rto/default.1.1.txt

@@ -0,0 +1,30 @@
+fe_only -DTEST_NUMBER=1 --gnu_version 150200 Test_name.c
+"Test_name.c", line 23: error: expression must have a constant value
+  static_assert(max + 1 != 0, "");   // Error: overflow
+                ^
+"Test_name.c", line 23: note: value exceeds range of "__int128"
+  static_assert(max + 1 != 0, "");   // Error: overflow
+                    ^
+
+"Test_name.c", line 24: error: expression must have a constant value
+  static_assert(min / -1 != 0, "");  // Error: overflow
+                ^
+"Test_name.c", line 24: note: integer operation result is out of range
+  static_assert(min / -1 != 0, "");  // Error: overflow
+                    ^
+
+"Test_name.c", line 25: error: expression must have a constant value
+  static_assert(max * 2 != 0, "");   // Error: overflow
+                ^
+"Test_name.c", line 25: note: value exceeds range of "__int128"
+  static_assert(max * 2 != 0, "");   // Error: overflow
+                    ^
+
+"Test_name.c", line 26: error: expression must have a constant value
+  static_assert(min * 2 != 0, "");   // Error: overflow
+                ^
+"Test_name.c", line 26: note: value exceeds range of "__int128"
+  static_assert(min * 2 != 0, "");   // Error: overflow
+                    ^
+
+4 errors detected in the compilation of "Test_name.c".

tests/tests/changes/GH38.sft.cpp

@@ -0,0 +1,26 @@
+//type:fn
+//options:--gnu_version 150200
+//require:INT128_EXTENSIONS_ALLOWED 1
+//remark:[GH #38] Integer value limits for a 128-bit host integer representation
+// 10/20/26 [GH #38]
+//
+// Constant arithmetic on __int128 values that do not fit in 64 bits is
+// accepted, and overflow of the 128-bit range is still diagnosed.
+
+constexpr __int128 s = (__int128)1 << 100;
+static_assert(s * 4 == ((__int128)1 << 102), "");
+static_assert(-s * 4 == -((__int128)1 << 102), "");
+
+constexpr unsigned __int128 u = (unsigned __int128)1 << 100;
+static_assert(u * 4 == ((unsigned __int128)1 << 102), "");
+static_assert(u + u == ((unsigned __int128)1 << 101), "");
+
+constexpr __int128 max = (__int128)(~(unsigned __int128)0 >> 1);
+constexpr __int128 min = -max - 1;
+static_assert(max / 3 * 3 + 1 == max, "");
+static_assert(min + 1 == -max, "");
+
+static_assert(max + 1 != 0, "");   // Error: overflow
+static_assert(min / -1 != 0, "");  // Error: overflow
+static_assert(max * 2 != 0, "");   // Error: overflow
+static_assert(min * 2 != 0, "");   // Error: overflow