Unexpected runtime issue when migrating from Intel C++ Compiler 2025.0.1.28 to 2025.3.0.326

Nilesh_Shinde — Fri, 26 Dec 2025 08:14:26 GMT

Hello,

I am working on an application that was previously compiled with Intel C++ Compiler 2025.0.1.28. The application includes the following function, which is intended to return 1 if the input string is empty and 0 otherwise. With version 2025.0.1.28, the function behaved as expected.

int ParserCheckZeroLengthString(char* pStr)

{
// check if this is a zero-length string
if (NULL== pStr || pStr[0]=='\0')
{
return 1;
}
return 0;
}

After upgrading to Intel C++ Compiler 2025.3.0.326, the build completes successfully, but at runtime the function incorrectly returns 0 instead of 1 when the string is empty.

We are suspecting this issue may be related to compiler optimisations.

To address this, we attempted to disable or reduce optimisation using the following CMake flags, but they had no effect: Function continued to return 0 for empty parameter string.

////Disable optimisation

-DCMAKE_CXX_FLAGS_RELEASE="/Od /DNDEBUG"
-DCMAKE_C_FLAGS_RELEASE="/Od /DNDEBUG"

and
////Reduce optimisation level
-DCMAKE_CXX_FLAGS_RELEASE="/O2 /Ob2 /DNDEBUG"
-DCMAKE_C_FLAGS_RELEASE="/O2 /Ob2/DNDEBUG"

Question:
How can we compile the existing code base with Intel C++ Compiler 2025.3.0.326 while preserving the same runtime behaviour as with version 2025.0.1.28?

Re: Unexpected runtime issue when migrating from Intel C++ Compiler 2025.0.1.28 to 2025.3.0.326

Nilesh_Shinde — Fri, 26 Dec 2025 08:30:01 GMT

Adding printf("returning 1"); just before 'return 1;' statement in ParserCheckZeroLengthString function, code starts behaving correctly again. How to diagnose or fix this issue.?

topic Unexpected runtime issue when migrating from Intel C++ Compiler 2025.0.1.28 to 2025.3.0.326 in Intel® oneAPI DPC++/C++ Compiler

Unexpected runtime issue when migrating from Intel C++ Compiler 2025.0.1.28 to 2025.3.0.326

Re: Unexpected runtime issue when migrating from Intel C++ Compiler 2025.0.1.28 to 2025.3.0.326