Print float literals at full precision

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -2329,7 +2329,19 @@ bool Converter::VisitIntegerLiteral(clang::IntegerLiteral *expr) {
 }
 
 bool Converter::VisitFloatingLiteral(clang::FloatingLiteral *expr) {
-  StrCat(GetNumAsString(expr->getValue()));
+  auto value = expr->getValue();
+  if (&value.getSemantics() != &llvm::APFloat::IEEEsingle()) {
+    bool loses_info = false;
+    value.convert(llvm::APFloat::IEEEdouble(),
+                  llvm::APFloat::rmNearestTiesToEven, &loses_info);
+  }
+  llvm::SmallString<32> str;
+  if (value.isInfinity()) {
+    str = "f64::INFINITY";
+  } else {
+    value.toString(str, /*FormatPrecision=*/0, /*FormatMaxPadding=*/0);
+  }
+  StrCat(str);
   computed_expr_type_ = ComputedExprType::FreshValue;
   return false;
 }

tests/unit/types.cpp

@@ -1,6 +1,7 @@
 // ADDITIONAL_COMPILE_FLAGS: -std=c++23
 
 #include <cassert>
+#include <cfloat>
 #include <cstddef>
 #include <cstdint>
 #include <inttypes.h>
@@ -25,6 +26,12 @@ int main() {
   std::nullptr_t xnp = nullptr;
   assert(xu8 + xu16 + xu32 + xu64 + xsz1 + xsz2 + xi1 + xi2 + xi3 + xi4 == 352);
   assert(xld * 2 == 3);
+  double pi = 3.14159265358979;
+  assert(pi < 3.141592654);
+  double dmax = -DBL_MAX;
+  assert(dmax < -1e308);
+  long double ldmax = LDBL_MAX;
+  assert(ldmax > DBL_MAX);
   assert(xwc + xc8 + xc16 + xc32 == 266);
   assert(xnp == nullptr);
   return 0;