Build issue with MSVS 2010 and the C++ standard

问题:

I'm trying to build, using msvs 2010 the project found at the following git:

https://github.com/Joonhwan/exprtk

The problem is when I comment out the line 48 '#define exprtk_lean_and_mean' in exprtk.hpp file, I get the following compiler error:

Error   1   error C1128: number of sections exceeded object file format limit : compile with /bigobj

Googling the error, seems to indicate the the compiled translation unit has compiled to something larger than an arbitariy limit, and adding 'bigobj' to the command line should fix the problem (which it does). Compiling the code with gcc (4.3), works without a glitch.

My questions are:

1. Does c++ place a limit on the number of types that can be had in a translation unit?

2. Is the way the code is laid out in this project bad practice? (when googling I noticed a lot of boost libraries have the same problem eg: Boost.Sprit)

回答1:

Does c++ place a limit on the number of types that can be had in a translation unit?

Note that the maximum values of such parameters are left open for particular implementations. The standard only enforces minimum requirements that must be supported by an implementation. An implementation will document the maximum values it supports and in this case MSVC implementation does so.

These are defined in a special section of the C++ standard.

Annex B - Implementation quantities

1. Because computers are finite, C + + implementations are inevitably limited in the size of the programs they can successfully process. Every implementation shall document those limitations where known. This documentation may cite fixed limits where they exist, say how to compute variable limits as a function of available resources, or say that fixed limits do not exist or are unknown.

2. The limits may constrain quantities that include those described below or others. The bracketed number following each quantity is recommended as the minimum for that quantity. However, these quantities are only guidelines and do not determine compliance.
   — Nesting levels of compound statements, iteration control structures, and selection control structures [256].
   — Nesting levels of conditional inclusion [256].
   — Pointer, array, and function declarators (in any combination) modifying an arithmetic, structure, union, or incomplete type in a declaration [256].
   — Nesting levels of parenthesized expressions within a full expression [256].
   — Number of characters in an internal identifier or macro name [1 024].
   — Number of characters in an external identifier [1 024].
   — External identifiers in one translation unit [65 536].
   — Identifiers with block scope declared in one block [1 024].
   — Macro identifiers simultaneously defined in one translation unit [65 536].
   — Parameters in one function definition [256].
   — Arguments in one function call [256].**
   — Parameters in one macro definition [256].
   — Arguments in one macro invocation [256].
   — Characters in one logical source line [65 536].
   — Characters in a character string literal or wide string literal (after concatenation) [65 536].
   — Size of an object [262 144].
   — Nesting levels for #include files [256].
   — Case labels for a switch statement (excluding those for any nested switch statements) [16 384].
   — Data members in a single class, structure, or union [16 384].
   — Enumeration constants in a single enumeration [4 096].
   — Levels of nested class, structure, or union definitions in a single struct-declaration-list [256].
   — Functions registered by atexit()[32].
   — Direct and indirect base classes [16 384].
   — Direct base classes for a single class [1024].
   — Members declared in a single class [4 096].
   — Final overriding virtual functions in a class, accessible or not [16 384].
   — Direct and indirect virtual bases of a class [1 024].
   — Static members of a class [1 024].
   — Friend declarations in a class [4 096].
   — Access control declarations in a class [4 096].
   — Member initializers in a constructor definition [6 144].
   — Scope qualifications of one identifier [256].
   — Nested external specifications [1 024].
   — Template arguments in a template declaration [1 024].
   — Recursively nested template instantiations [17].
   — Handlers per try block [256].
   — Throw specifications on a single function declaration [256].

回答2:

The limitation is inside OBJ format used by old versions of MSVC and corresponding linkers. So while this restriction is arbitrary it could not be made default behavior for new versions of compilers. Check out description of the /bigobj option:

Linkers that shipped prior to Visual C++ 2005 cannot read .obj files that were produced with /bigobj.