PRB: /Tp and /Tc Show Unexpected Behavior with Wildcards (85498)

SYMPTOMS

When compiling multiple .CPP or .CXX files using a wildcard syntax and the /Tc command line option, for example

   cl /Tc *.cpp

the C compiler is invoked only for the first source file matching the wildcard specification. For all subsequent files, the C++ compiler is invoked. The inverse is also true. That is, when compiling multiple .C files using a wildcard syntax and the /Tp command line option, the C++ compiler is invoked only for the first file; for all subsequent files, the C compiler is invoked.

CAUSE

This behavior is by design. As stated in the online and hard copy documentation for Microsoft C/C++ version 7.0 and all versions of Microsoft Visual C++ 16- and 32-bit Editions, the following is the correct syntax for the /Tc and /Tp command line options:

/Tc<filename>   -or-   /Tc <filename>
/Tp<filename>   -or-   /Tp <filename>

Each option refers to only one source file. Therefore, the first file matching the wildcard specification will be compiled as directed by the corresponding /T? option. All other files matching the wildcard will be compiled in accordance with their extension. (The C compiler is invoked for .C files, the C++ compiler for .CPP or .CXX files.)

MORE INFORMATION

The following are two possible workarounds for the potential inconvenience presented by this behavior:

Use a makefile to control compilations involving the /Tc or /Tp switch. Instead of using wildcards, list the files as dependents of the respective .OBJ files. This offers two advantages over using wildcards:
- Only the files that have changed with respect to their .OBJ are recompiled.
- The proper compiler is invoked for the file to be compiled.
-or-
Rename all files in question such that they have the expected extensions. For example, rename SRC.CPP to SRC.C if you want the C compiler to be invoked on the source.

The sample code below is a makefile that could be used to replace the wildcard command-line compilation:

Sample Code

If you wish to compile file1.c, file2.c and file3.c with the C++ compiler and link them to create exefile.exe, use the following makefile:

.c.obj:
   cl /c /Tp $<

exefile.exe : file1.obj file2.obj file3.obj
   link $**, exefile.exe;