[cfe-dev] Defines in preprocessed files

[Mikhail Ramalho via cfe-dev]

Hi Justin,

Thank you very much, it worked!

2016-01-25 22:08 GMT+00:00 Justin Bogner <mail at justinbogner.com>:

> Mikhail Ramalho via cfe-dev <cfe-dev at lists.llvm.org> writes:
> > Hi all,
> >
> > I'm working on a project to use clang as a frontend to a model checking
> > tool.
> >
> > It's almost done but I'm now facing a problem that I couldn't find a
> > solution: How to force the preprocessor to run in already preprocessed
> > files?
> >
> > For example, something as simples as:
> >
> > int main(void)
> > {
> >   int a = x();
> > }
> >
> > When using clangTool to generate the AST, it works fine if add something
> > like -Dx=x1. The generated AST looks like:
> >
> > FunctionDecl 0x3a8c290 </home/mramalho/main.c:2:1, line:5:1> line:2:5
> main
> > 'int (void)'
> > `-CompoundStmt 0x3a8c5c0 <line:3:1, line:5:1>
> >   `-DeclStmt 0x3a8c5a8 <line:4:3, col:14>
> >     `-VarDecl 0x3a8c3b8 <col:3, col:13> col:7 a 'int' cinit
> >       `-CallExpr 0x3a8c580 <<command line>:6:11,
> > /home/mramalho/main.c:4:13> 'int'
> >         `-ImplicitCastExpr 0x3a8c568 <<command line>:6:11> 'int (*)()'
> > <FunctionToPointerDecay>
> > *          `-DeclRefExpr 0x3a8c510 <col:11> 'int ()' Function 0x3a8c468
> > 'x1' 'int ()'*
> >
> > But if I preprocess the file:
> >
> > $ clang -E main.c > main.c.i
> >
> > # 1 "main.c"
> > # 1 "<built-in>" 1
> > # 1 "<built-in>" 3
> > # 316 "<built-in>" 3
> > # 1 "<command line>" 1
> > # 1 "<built-in>" 2
> > # 1 "main.c" 2
> >
> > int main(void)
> > {
> >   int a = x();
> > }
> >
> > and run with the same define -Dx=x1, the AST is:
> >
> > FunctionDecl 0x2e583a0 <main.c:2:1, line:5:1> line:2:5 main 'int (void)'
> > `-CompoundStmt 0x2e586d0 <line:3:1, line:5:1>
> >   `-DeclStmt 0x2e586b8 <line:4:3, col:14>
> >     `-VarDecl 0x2e584c8 <col:3, col:13> col:7 a 'int' cinit
> >       `-CallExpr 0x2e58690 <col:11, col:13> 'int'
> >         `-ImplicitCastExpr 0x2e58678 <col:11> 'int (*)()'
> > <FunctionToPointerDecay>
> > *          `-DeclRefExpr 0x2e58620 <col:11> 'int ()' Function 0x2e58578
> 'x'
> > 'int ()'*
> >
> > I guess the preprocessor is not running, given the following message I
> get
> > when directly using clang:
> >
> > $ clang -E -Dx=x1 main.c.i
> > clang: warning: main.c.i: previously preprocessed input
> > clang: warning: argument unused during compilation: '-D x=x1'
> >
> > Is there an option to force the preprocessor to run again?
>
> clang is guessing that this is preprocessed based on the extension. One
> option is to tell clang what language you want to treat the file as with
> a -x argument:
>
>   clang -E -Dx=x1 -x c main.c.i
>
> > Unfortunately, I need to change some function calls, even when the file
> is
> > preprocessed.
> >
> > Thank you,
>



-- 

Mikhail Ramalho.
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