Merge pull request #21110 from jketema/jketema/rm-decimal

C++: Remove decimal floating point types

cpp/downgrades/d2d611b3fdcc7c4fe370f0d115200a3aa6ad5837/upgrade.properties

@@ -0,0 +1,2 @@
+description: Remove _Decimal{32,64,128} types
+compatibility: full

cpp/ql/lib/change-notes/2026-01-02-decimal-removal.md

@@ -0,0 +1,4 @@
+---
+category: breaking
+---
+* The `_Decimal32`, `_Decimal64`, and `_Decimal128` types are no longer exposed as builtin types. Support for these gcc-specific types was incomplete, and are generally not used in C/C++ codebases.

cpp/ql/lib/semmle/code/cpp/Type.qll

@@ -802,15 +802,6 @@ private predicate floatingPointTypeMapping(
   // _Complex __float128
   kind = 39 and base = 2 and domain = TComplexDomain() and realKind = 38 and extended = false
   or
-  // _Decimal32
-  kind = 40 and base = 10 and domain = TRealDomain() and realKind = 40 and extended = false
-  or
-  // _Decimal64
-  kind = 41 and base = 10 and domain = TRealDomain() and realKind = 41 and extended = false
-  or
-  // _Decimal128
-  kind = 42 and base = 10 and domain = TRealDomain() and realKind = 42 and extended = false
-  or
   // _Float32
   kind = 45 and base = 2 and domain = TRealDomain() and realKind = 45 and extended = false
   or
@@ -871,9 +862,8 @@ private predicate floatingPointTypeMapping(
 
 /**
  * The C/C++ floating point types. See 4.5.  This includes `float`, `double` and `long double`, the
- * fixed-size floating-point types like `_Float32`, the extended-precision floating-point types like
- * `_Float64x`, and the decimal floating-point types like `_Decimal32`. It also includes the complex
- * and imaginary versions of all of these types.
+ * fixed-size floating-point types like `_Float32`, and the extended-precision floating-point types
+ * like `_Float64x`. It also includes the complex and imaginary versions of all of these types.
  */
 class FloatingPointType extends ArithmeticType {
   final int base;
@@ -991,42 +981,6 @@ class Float128Type extends RealNumberType, BinaryFloatingPointType {
   override string getAPrimaryQlClass() { result = "Float128Type" }
 }
 
-/**
- * The GNU C `_Decimal32` primitive type.  This is not standard C/C++.
- * ```
- * _Decimal32 d32;
- * ```
- */
-class Decimal32Type extends RealNumberType, DecimalFloatingPointType {
-  Decimal32Type() { builtintypes(underlyingElement(this), _, 40, _, _, _) }
-
-  override string getAPrimaryQlClass() { result = "Decimal32Type" }
-}
-
-/**
- * The GNU C `_Decimal64` primitive type.  This is not standard C/C++.
- * ```
- * _Decimal64 d64;
- * ```
- */
-class Decimal64Type extends RealNumberType, DecimalFloatingPointType {
-  Decimal64Type() { builtintypes(underlyingElement(this), _, 41, _, _, _) }
-
-  override string getAPrimaryQlClass() { result = "Decimal64Type" }
-}
-
-/**
- * The GNU C `_Decimal128` primitive type.  This is not standard C/C++.
- * ```
- * _Decimal128 d128;
- * ```
- */
-class Decimal128Type extends RealNumberType, DecimalFloatingPointType {
-  Decimal128Type() { builtintypes(underlyingElement(this), _, 42, _, _, _) }
-
-  override string getAPrimaryQlClass() { result = "Decimal128Type" }
-}
-
 /**
  * The C/C++ `void` type. See 4.7.
  * ```

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -617,9 +617,9 @@ case @builtintype.kind of
 | 37 = @signed_int128         // signed __int128
 | 38 = @float128              // __float128
 | 39 = @complex_float128      // _Complex __float128
-| 40 = @decimal32             // _Decimal32
-| 41 = @decimal64             // _Decimal64
-| 42 = @decimal128            // _Decimal128
+// ... 40 _Decimal32
+// ... 41 _Decimal64
+// ... 42 _Decimal128
 | 43 = @char16_t
 | 44 = @char32_t
 | 45 = @std_float32           // _Float32

cpp/ql/lib/upgrades/a42ce5fc943254097f85471b94ae2247e819104a/builtintypes.ql

@@ -0,0 +1,11 @@
+class BuiltinType extends @builtintype {
+  string toString() { none() }
+}
+
+predicate isDecimalBuiltinType(BuiltinType type) { builtintypes(type, _, [40, 41, 42], _, _, _) }
+
+from BuiltinType type, string name, int kind, int kind_new, int size, int sign, int alignment
+where
+  builtintypes(type, name, kind, size, sign, alignment) and
+  if isDecimalBuiltinType(type) then kind_new = 1 else kind_new = kind
+select type, name, kind_new, size, sign, alignment

cpp/ql/lib/upgrades/a42ce5fc943254097f85471b94ae2247e819104a/upgrade.properties

@@ -0,0 +1,3 @@
+description: Remove _Decimal{32,64,128} types
+compatibility: partial
+builtintypes.rel: run builtintypes.qlo

cpp/ql/test/library-tests/builtins/types/types.c

@@ -1,5 +0,0 @@
-
-_Decimal32 d32;
-_Decimal64 d64;
-_Decimal128 d128;
-

cpp/ql/test/library-tests/builtins/types/types.expected

@@ -1,7 +0,0 @@
-| file://:0:0:0:0 | fp_offset | file://:0:0:0:0 | unsigned int |
-| file://:0:0:0:0 | gp_offset | file://:0:0:0:0 | unsigned int |
-| file://:0:0:0:0 | overflow_arg_area | file://:0:0:0:0 | void * |
-| file://:0:0:0:0 | reg_save_area | file://:0:0:0:0 | void * |
-| types.c:2:12:2:14 | d32 | file://:0:0:0:0 | _Decimal32 |
-| types.c:3:12:3:14 | d64 | file://:0:0:0:0 | _Decimal64 |
-| types.c:4:13:4:16 | d128 | file://:0:0:0:0 | _Decimal128 |

cpp/ql/test/library-tests/builtins/types/types.ql

@@ -1,5 +0,0 @@
-import cpp
-
-from Variable v, Type t
-where t = v.getType()
-select v, t

cpp/ql/test/library-tests/literals/literals/literals.c

@@ -1,6 +1,4 @@
 
-double dd = 1.0d;
-double dD = 1.0D;
 double df = 1.0f;
 double dF = 1.0F;
 double di = 1.0i;

cpp/ql/test/library-tests/literals/literals/literals.expected

@@ -1,14 +1,12 @@
 | literals.c:2:13:2:16 | 1.0 |
 | literals.c:3:13:3:16 | 1.0 |
-| literals.c:4:13:4:16 | 1.0 |
-| literals.c:5:13:5:16 | 1.0 |
+| literals.c:4:13:4:16 | (0.0,1.0i) |
+| literals.c:5:13:5:16 | (0.0,1.0i) |
 | literals.c:6:13:6:16 | (0.0,1.0i) |
 | literals.c:7:13:7:16 | (0.0,1.0i) |
-| literals.c:8:13:8:16 | (0.0,1.0i) |
-| literals.c:9:13:9:16 | (0.0,1.0i) |
+| literals.c:8:13:8:16 | 1.0 |
+| literals.c:9:13:9:16 | 1.0 |
 | literals.c:10:13:10:16 | 1.0 |
 | literals.c:11:13:11:16 | 1.0 |
 | literals.c:12:13:12:16 | 1.0 |
 | literals.c:13:13:13:16 | 1.0 |
-| literals.c:14:13:14:16 | 1.0 |
-| literals.c:15:13:15:16 | 1.0 |

cpp/ql/test/library-tests/templates/type_instantiations/types.expected

@@ -12,9 +12,6 @@
 | file://:0:0:0:0 | _Complex float |
 | file://:0:0:0:0 | _Complex long double |
 | file://:0:0:0:0 | _Complex std::float16_t |
-| file://:0:0:0:0 | _Decimal32 |
-| file://:0:0:0:0 | _Decimal64 |
-| file://:0:0:0:0 | _Decimal128 |
 | file://:0:0:0:0 | _Float16 |
 | file://:0:0:0:0 | _Float32 |
 | file://:0:0:0:0 | _Float32x |

cpp/ql/test/library-tests/type_sizes/type_sizes.expected

@@ -32,9 +32,6 @@
 | file://:0:0:0:0 | _Complex float | 8 |
 | file://:0:0:0:0 | _Complex long double | 32 |
 | file://:0:0:0:0 | _Complex std::float16_t | 4 |
-| file://:0:0:0:0 | _Decimal32 | 4 |
-| file://:0:0:0:0 | _Decimal64 | 8 |
-| file://:0:0:0:0 | _Decimal128 | 16 |
 | file://:0:0:0:0 | _Float16 | 2 |
 | file://:0:0:0:0 | _Float32 | 4 |
 | file://:0:0:0:0 | _Float32x | 8 |

cpp/ql/test/library-tests/unspecified_type/types/unspecified_type.expected

@@ -14,9 +14,6 @@
 | file://:0:0:0:0 | _Complex float | _Complex float |
 | file://:0:0:0:0 | _Complex long double | _Complex long double |
 | file://:0:0:0:0 | _Complex std::float16_t | _Complex std::float16_t |
-| file://:0:0:0:0 | _Decimal32 | _Decimal32 |
-| file://:0:0:0:0 | _Decimal64 | _Decimal64 |
-| file://:0:0:0:0 | _Decimal128 | _Decimal128 |
 | file://:0:0:0:0 | _Float16 | _Float16 |
 | file://:0:0:0:0 | _Float32 | _Float32 |
 | file://:0:0:0:0 | _Float32x | _Float32x |

cpp/ql/test/library-tests/variables/variables/types.expected

@@ -13,9 +13,6 @@
 | _Complex float | BinaryFloatingPointType, ComplexNumberType, GuardConditionImpl |  |  |  |  |
 | _Complex long double | BinaryFloatingPointType, ComplexNumberType, GuardConditionImpl |  |  |  |  |
 | _Complex std::float16_t | BinaryFloatingPointType, ComplexNumberType, GuardConditionImpl |  |  |  |  |
-| _Decimal32 | Decimal32Type, GuardConditionImpl |  |  |  |  |
-| _Decimal64 | Decimal64Type, GuardConditionImpl |  |  |  |  |
-| _Decimal128 | Decimal128Type, GuardConditionImpl |  |  |  |  |
 | _Float16 | BinaryFloatingPointType, GuardConditionImpl, RealNumberType |  |  |  |  |
 | _Float32 | BinaryFloatingPointType, GuardConditionImpl, RealNumberType |  |  |  |  |
 | _Float32x | BinaryFloatingPointType, GuardConditionImpl, RealNumberType |  |  |  |  |