Microsoft KB Archive/113061

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BUG: Incorrect C4762 Generated with Optimizing Compiler

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Q113061

7.00 | 1.00 1.50 MS-DOS | WINDOWS kbtool kbbuglist - The information in this article applies to: - The Microsoft C/C++ Compiler (CL.EXE), included with: - Microsoft C/C++ for MS-DOS, version 7.0 - Microsoft Visual C++ for Windows, versions 1.0 and 1.5 - SYMPTOMS ======== When compiling in compact, large, or huge memory model, the optimizing compiler incorrectly generates the warning: warning C4762: Near/far mismatch in argument: conversion supplied The warning appears when generating far pointer references to near variables and then passing those references to functions that explicitly expect near pointers. STATUS ====== Microsoft has confirmed this to be a problem in C/C++ versions 7.0, 8.0, and 8.0c. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available. MORE INFORMATION ================ Code demonstrating this problem is shown below. When building under large or compact model, cases 1 and 2 will force a near/far conversion. Because the compiler does not know where the pointer reference to the near variables will be used, it produces a far pointer to conform with the model chosen. The compiler then converts the far pointer into a near pointer again because func1 expects a near pointer. Despite these warnings, the code is correct and the two function calls execute correctly. In the Case 3, the variable is already a near pointer. No conversions are necessary, and therefore no warning occurs. Sample Code --- /* Compile options needed: /AL ( or /AC or /AH) /f- */ /* Any type for "testtype" produces the error where noted */ typedef int testtype; testtype _near narrtype[ 100 ]; testtype _near ntype; testtype _near *nptype; void _near func1( testtype _near *np_funcvar) {} void main(void) { func1(narrtype); // Causes C4762 func1(&ntype); // Causes C4762 nptype = narrtype; func1(nptype); //Does NOT cause C4762 } Additional reference words: 1.00 1.50 7.00 8.00 8.00c KBCategory: kbtool kbbuglist KBSubcategory: CLIss

Keywords : kb16bitonly

Issue type : kbbug

Technology : kbVCsearch kbAudDeveloper kbCVCComp