Fix #12282 (Internal error: fail to parse 1.0e4931L)

A float literal out of the range of double, such as 1.0e4931L or glibc's
HUGE_VAL for compilers other than GCC (1e10000), stopped the analysis of
the whole file with
  Internal Error. MathLib::toDoubleNumber: conversion failed: 1e10000
The stream stores the largest finite value and fails on such a literal;
compilers make it infinity, so do the same.

Author: pduchi

lib/mathlib.cpp

@@ -532,8 +532,15 @@ double MathLib::toDoubleNumber(const std::string &str, const Token * const tok)
     std::istringstream istr(str);
     istr.imbue(std::locale::classic());
     double ret;
-    if (!(istr >> ret))
-        throw InternalError(tok, "Internal Error. MathLib::toDoubleNumber: conversion failed: " + str);
+    if (!(istr >> ret)) {
+        // Out of the range of double, such as 1e10000 (glibc's HUGE_VAL for
+        // compilers other than GCC): the stream stores the largest finite
+        // value and fails, a compiler makes it infinity.
+        if (!isFloat(str) || std::fabs(ret) < std::numeric_limits<double>::max())
+            throw InternalError(tok, "Internal Error. MathLib::toDoubleNumber: conversion failed: " + str);
+        ret = std::copysign(std::numeric_limits<double>::infinity(), ret);
+        istr.clear();
+    }
     std::string s;
     if (istr >> s) {
         if (isDecimalFloat(str))

test/testmathlib.cpp

@@ -22,6 +22,7 @@
 #include "token.h"
 #include "tokenlist.h"
 
+#include <cmath>
 #include <limits>
 #include <memory>
 #include <string>
@@ -677,6 +678,13 @@ class TestMathLib : public TestFixture {
         ASSERT_EQUALS_DOUBLE(static_cast<double>('\200'), MathLib::toDoubleNumber("'\\200'"), 0.000001);
         ASSERT_EQUALS_DOUBLE(static_cast<double>(L'A'),   MathLib::toDoubleNumber("L'A'"), 0.000001);
 
+        // out of the range of double, like glibc's HUGE_VAL for compilers other than GCC
+        ASSERT_EQUALS(true, std::isinf(MathLib::toDoubleNumber("1e10000")));
+        ASSERT_EQUALS(true, std::isinf(MathLib::toDoubleNumber("1e10000f")));
+        ASSERT_EQUALS(true, std::isinf(MathLib::toDoubleNumber("1e10000L")));
+        ASSERT_EQUALS(true, std::isinf(MathLib::toDoubleNumber("1.5E+400")));
+        ASSERT_EQUALS(true, std::isinf(MathLib::toDoubleNumber("1.0e4931L"))); // #12282
+
         ASSERT_THROW_INTERNAL_EQUALS(MathLib::toDoubleNumber("invalid"), INTERNAL, "Internal Error. MathLib::toDoubleNumber: conversion failed: invalid");
 
         // AppleClang before 18 reports a different error