init

scons-local-3.0.0/SCons/Conftest.py

@@ -0,0 +1,812 @@
+"""SCons.Conftest
+
+Autoconf-like configuration support; low level implementation of tests.
+"""
+
+#
+# Copyright (c) 2003 Stichting NLnet Labs
+# Copyright (c) 2001, 2002, 2003 Steven Knight
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+#
+# The purpose of this module is to define how a check is to be performed.
+# Use one of the Check...() functions below.
+#
+
+#
+# A context class is used that defines functions for carrying out the tests,
+# logging and messages.  The following methods and members must be present:
+#
+# context.Display(msg)  Function called to print messages that are normally
+#                       displayed for the user.  Newlines are explicitly used.
+#                       The text should also be written to the logfile!
+#
+# context.Log(msg)      Function called to write to a log file.
+#
+# context.BuildProg(text, ext)
+#                       Function called to build a program, using "ext" for the
+#                       file extention.  Must return an empty string for
+#                       success, an error message for failure.
+#                       For reliable test results building should be done just
+#                       like an actual program would be build, using the same
+#                       command and arguments (including configure results so
+#                       far).
+#
+# context.CompileProg(text, ext)
+#                       Function called to compile a program, using "ext" for
+#                       the file extention.  Must return an empty string for
+#                       success, an error message for failure.
+#                       For reliable test results compiling should be done just
+#                       like an actual source file would be compiled, using the
+#                       same command and arguments (including configure results
+#                       so far).
+#
+# context.AppendLIBS(lib_name_list)
+#                       Append "lib_name_list" to the value of LIBS.
+#                       "lib_namelist" is a list of strings.
+#                       Return the value of LIBS before changing it (any type
+#                       can be used, it is passed to SetLIBS() later.)
+#
+# context.PrependLIBS(lib_name_list)
+#                       Prepend "lib_name_list" to the value of LIBS.
+#                       "lib_namelist" is a list of strings.
+#                       Return the value of LIBS before changing it (any type
+#                       can be used, it is passed to SetLIBS() later.)
+#
+# context.SetLIBS(value)
+#                       Set LIBS to "value".  The type of "value" is what
+#                       AppendLIBS() returned.
+#                       Return the value of LIBS before changing it (any type
+#                       can be used, it is passed to SetLIBS() later.)
+#
+# context.headerfilename
+#                       Name of file to append configure results to, usually
+#                       "confdefs.h".
+#                       The file must not exist or be empty when starting.
+#                       Empty or None to skip this (some tests will not work!).
+#
+# context.config_h      (may be missing). If present, must be a string, which
+#                       will be filled with the contents of a config_h file.
+#
+# context.vardict       Dictionary holding variables used for the tests and
+#                       stores results from the tests, used for the build
+#                       commands.
+#                       Normally contains "CC", "LIBS", "CPPFLAGS", etc.
+#
+# context.havedict      Dictionary holding results from the tests that are to
+#                       be used inside a program.
+#                       Names often start with "HAVE_".  These are zero
+#                       (feature not present) or one (feature present).  Other
+#                       variables may have any value, e.g., "PERLVERSION" can
+#                       be a number and "SYSTEMNAME" a string.
+#
+
+import re
+
+#
+# PUBLIC VARIABLES
+#
+
+LogInputFiles = 1    # Set that to log the input files in case of a failed test
+LogErrorMessages = 1 # Set that to log Conftest-generated error messages
+
+#
+# PUBLIC FUNCTIONS
+#
+
+# Generic remarks:
+# - When a language is specified which is not supported the test fails.  The
+#   message is a bit different, because not all the arguments for the normal
+#   message are available yet (chicken-egg problem).
+
+
+def CheckBuilder(context, text = None, language = None):
+    """
+    Configure check to see if the compiler works.
+    Note that this uses the current value of compiler and linker flags, make
+    sure $CFLAGS, $CPPFLAGS and $LIBS are set correctly.
+    "language" should be "C" or "C++" and is used to select the compiler.
+    Default is "C".
+    "text" may be used to specify the code to be build.
+    Returns an empty string for success, an error message for failure.
+    """
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("%s\n" % msg)
+        return msg
+
+    if not text:
+        text = """
+int main() {
+    return 0;
+}
+"""
+
+    context.Display("Checking if building a %s file works... " % lang)
+    ret = context.BuildProg(text, suffix)
+    _YesNoResult(context, ret, None, text)
+    return ret
+
+def CheckCC(context):
+    """
+    Configure check for a working C compiler.
+
+    This checks whether the C compiler, as defined in the $CC construction
+    variable, can compile a C source file. It uses the current $CCCOM value
+    too, so that it can test against non working flags.
+
+    """
+    context.Display("Checking whether the C compiler works... ")
+    text = """
+int main()
+{
+    return 0;
+}
+"""
+    ret = _check_empty_program(context, 'CC', text, 'C')
+    _YesNoResult(context, ret, None, text)
+    return ret
+
+def CheckSHCC(context):
+    """
+    Configure check for a working shared C compiler.
+
+    This checks whether the C compiler, as defined in the $SHCC construction
+    variable, can compile a C source file. It uses the current $SHCCCOM value
+    too, so that it can test against non working flags.
+
+    """
+    context.Display("Checking whether the (shared) C compiler works... ")
+    text = """
+int foo()
+{
+    return 0;
+}
+"""
+    ret = _check_empty_program(context, 'SHCC', text, 'C', use_shared = True)
+    _YesNoResult(context, ret, None, text)
+    return ret
+
+def CheckCXX(context):
+    """
+    Configure check for a working CXX compiler.
+
+    This checks whether the CXX compiler, as defined in the $CXX construction
+    variable, can compile a CXX source file. It uses the current $CXXCOM value
+    too, so that it can test against non working flags.
+
+    """
+    context.Display("Checking whether the C++ compiler works... ")
+    text = """
+int main()
+{
+    return 0;
+}
+"""
+    ret = _check_empty_program(context, 'CXX', text, 'C++')
+    _YesNoResult(context, ret, None, text)
+    return ret
+
+def CheckSHCXX(context):
+    """
+    Configure check for a working shared CXX compiler.
+
+    This checks whether the CXX compiler, as defined in the $SHCXX construction
+    variable, can compile a CXX source file. It uses the current $SHCXXCOM value
+    too, so that it can test against non working flags.
+
+    """
+    context.Display("Checking whether the (shared) C++ compiler works... ")
+    text = """
+int main()
+{
+    return 0;
+}
+"""
+    ret = _check_empty_program(context, 'SHCXX', text, 'C++', use_shared = True)
+    _YesNoResult(context, ret, None, text)
+    return ret
+
+def _check_empty_program(context, comp, text, language, use_shared = False):
+    """Return 0 on success, 1 otherwise."""
+    if comp not in context.env or not context.env[comp]:
+        # The compiler construction variable is not set or empty
+        return 1
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        return 1
+
+    if use_shared:
+        return context.CompileSharedObject(text, suffix)
+    else:
+        return context.CompileProg(text, suffix)
+
+
+def CheckFunc(context, function_name, header = None, language = None):
+    """
+    Configure check for a function "function_name".
+    "language" should be "C" or "C++" and is used to select the compiler.
+    Default is "C".
+    Optional "header" can be defined to define a function prototype, include a
+    header file or anything else that comes before main().
+    Sets HAVE_function_name in context.havedict according to the result.
+    Note that this uses the current value of compiler and linker flags, make
+    sure $CFLAGS, $CPPFLAGS and $LIBS are set correctly.
+    Returns an empty string for success, an error message for failure.
+    """
+
+    # Remarks from autoconf:
+    # - Don't include <ctype.h> because on OSF/1 3.0 it includes <sys/types.h>
+    #   which includes <sys/select.h> which contains a prototype for select.
+    #   Similarly for bzero.
+    # - assert.h is included to define __stub macros and hopefully few
+    #   prototypes, which can conflict with char $1(); below.
+    # - Override any gcc2 internal prototype to avoid an error.
+    # - We use char for the function declaration because int might match the
+    #   return type of a gcc2 builtin and then its argument prototype would
+    #   still apply.
+    # - The GNU C library defines this for functions which it implements to
+    #   always fail with ENOSYS.  Some functions are actually named something
+    #   starting with __ and the normal name is an alias.
+
+    if context.headerfilename:
+        includetext = '#include "%s"' % context.headerfilename
+    else:
+        includetext = ''
+    if not header:
+        header = """
+#ifdef __cplusplus
+extern "C"
+#endif
+char %s();""" % function_name
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("Cannot check for %s(): %s\n" % (function_name, msg))
+        return msg
+
+    text = """
+%(include)s
+#include <assert.h>
+%(hdr)s
+
+int main() {
+#if defined (__stub_%(name)s) || defined (__stub___%(name)s)
+  fail fail fail
+#else
+  %(name)s();
+#endif
+
+  return 0;
+}
+""" % { 'name': function_name,
+        'include': includetext,
+        'hdr': header }
+
+    context.Display("Checking for %s function %s()... " % (lang, function_name))
+    ret = context.BuildProg(text, suffix)
+    _YesNoResult(context, ret, "HAVE_" + function_name, text,
+                 "Define to 1 if the system has the function `%s'." %\
+                 function_name)
+    return ret
+
+
+def CheckHeader(context, header_name, header = None, language = None,
+                                                        include_quotes = None):
+    """
+    Configure check for a C or C++ header file "header_name".
+    Optional "header" can be defined to do something before including the
+    header file (unusual, supported for consistency).
+    "language" should be "C" or "C++" and is used to select the compiler.
+    Default is "C".
+    Sets HAVE_header_name in context.havedict according to the result.
+    Note that this uses the current value of compiler and linker flags, make
+    sure $CFLAGS and $CPPFLAGS are set correctly.
+    Returns an empty string for success, an error message for failure.
+    """
+    # Why compile the program instead of just running the preprocessor?
+    # It is possible that the header file exists, but actually using it may
+    # fail (e.g., because it depends on other header files).  Thus this test is
+    # more strict.  It may require using the "header" argument.
+    #
+    # Use <> by default, because the check is normally used for system header
+    # files.  SCons passes '""' to overrule this.
+
+    # Include "confdefs.h" first, so that the header can use HAVE_HEADER_H.
+    if context.headerfilename:
+        includetext = '#include "%s"\n' % context.headerfilename
+    else:
+        includetext = ''
+    if not header:
+        header = ""
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("Cannot check for header file %s: %s\n"
+                                                          % (header_name, msg))
+        return msg
+
+    if not include_quotes:
+        include_quotes = "<>"
+
+    text = "%s%s\n#include %s%s%s\n\n" % (includetext, header,
+                             include_quotes[0], header_name, include_quotes[1])
+
+    context.Display("Checking for %s header file %s... " % (lang, header_name))
+    ret = context.CompileProg(text, suffix)
+    _YesNoResult(context, ret, "HAVE_" + header_name, text, 
+                 "Define to 1 if you have the <%s> header file." % header_name)
+    return ret
+
+
+def CheckType(context, type_name, fallback = None,
+                                               header = None, language = None):
+    """
+    Configure check for a C or C++ type "type_name".
+    Optional "header" can be defined to include a header file.
+    "language" should be "C" or "C++" and is used to select the compiler.
+    Default is "C".
+    Sets HAVE_type_name in context.havedict according to the result.
+    Note that this uses the current value of compiler and linker flags, make
+    sure $CFLAGS, $CPPFLAGS and $LIBS are set correctly.
+    Returns an empty string for success, an error message for failure.
+    """
+
+    # Include "confdefs.h" first, so that the header can use HAVE_HEADER_H.
+    if context.headerfilename:
+        includetext = '#include "%s"' % context.headerfilename
+    else:
+        includetext = ''
+    if not header:
+        header = ""
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("Cannot check for %s type: %s\n" % (type_name, msg))
+        return msg
+
+    # Remarks from autoconf about this test:
+    # - Grepping for the type in include files is not reliable (grep isn't
+    #   portable anyway).
+    # - Using "TYPE my_var;" doesn't work for const qualified types in C++.
+    #   Adding an initializer is not valid for some C++ classes.
+    # - Using the type as parameter to a function either fails for K&$ C or for
+    #   C++.
+    # - Using "TYPE *my_var;" is valid in C for some types that are not
+    #   declared (struct something).
+    # - Using "sizeof(TYPE)" is valid when TYPE is actually a variable.
+    # - Using the previous two together works reliably.
+    text = """
+%(include)s
+%(header)s
+
+int main() {
+  if ((%(name)s *) 0)
+    return 0;
+  if (sizeof (%(name)s))
+    return 0;
+}
+""" % { 'include': includetext,
+        'header': header,
+        'name': type_name }
+
+    context.Display("Checking for %s type %s... " % (lang, type_name))
+    ret = context.BuildProg(text, suffix)
+    _YesNoResult(context, ret, "HAVE_" + type_name, text,
+                 "Define to 1 if the system has the type `%s'." % type_name)
+    if ret and fallback and context.headerfilename:
+        f = open(context.headerfilename, "a")
+        f.write("typedef %s %s;\n" % (fallback, type_name))
+        f.close()
+
+    return ret
+
+def CheckTypeSize(context, type_name, header = None, language = None, expect = None):
+    """This check can be used to get the size of a given type, or to check whether
+    the type is of expected size.
+
+    Arguments:
+        - type : str
+            the type to check
+        - includes : sequence
+            list of headers to include in the test code before testing the type
+        - language : str
+            'C' or 'C++'
+        - expect : int
+            if given, will test wether the type has the given number of bytes.
+            If not given, will automatically find the size.
+
+        Returns:
+            status : int
+                0 if the check failed, or the found size of the type if the check succeeded."""
+    
+    # Include "confdefs.h" first, so that the header can use HAVE_HEADER_H.
+    if context.headerfilename:
+        includetext = '#include "%s"' % context.headerfilename
+    else:
+        includetext = ''
+
+    if not header:
+        header = ""
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("Cannot check for %s type: %s\n" % (type_name, msg))
+        return msg
+
+    src = includetext + header 
+    if not expect is None:
+        # Only check if the given size is the right one
+        context.Display('Checking %s is %d bytes... ' % (type_name, expect))
+
+        # test code taken from autoconf: this is a pretty clever hack to find that
+        # a type is of a given size using only compilation. This speeds things up
+        # quite a bit compared to straightforward code using TryRun
+        src = src + r"""
+typedef %s scons_check_type;
+
+int main()
+{
+    static int test_array[1 - 2 * !(((long int) (sizeof(scons_check_type))) == %d)];
+    test_array[0] = 0;
+
+    return 0;
+}
+"""
+
+        st = context.CompileProg(src % (type_name, expect), suffix)
+        if not st:
+            context.Display("yes\n")
+            _Have(context, "SIZEOF_%s" % type_name, expect, 
+                  "The size of `%s', as computed by sizeof." % type_name)
+            return expect
+        else:
+            context.Display("no\n")
+            _LogFailed(context, src, st)
+            return 0
+    else:
+        # Only check if the given size is the right one
+        context.Message('Checking size of %s ... ' % type_name)
+
+        # We have to be careful with the program we wish to test here since
+        # compilation will be attempted using the current environment's flags.
+        # So make sure that the program will compile without any warning. For
+        # example using: 'int main(int argc, char** argv)' will fail with the
+        # '-Wall -Werror' flags since the variables argc and argv would not be
+        # used in the program...
+        #
+        src = src + """
+#include <stdlib.h>
+#include <stdio.h>
+int main() {
+    printf("%d", (int)sizeof(""" + type_name + """));
+    return 0;
+}
+    """
+        st, out = context.RunProg(src, suffix)
+        try:
+            size = int(out)
+        except ValueError:
+            # If cannot convert output of test prog to an integer (the size),
+            # something went wront, so just fail
+            st = 1
+            size = 0
+
+        if not st:
+            context.Display("yes\n")
+            _Have(context, "SIZEOF_%s" % type_name, size,
+                  "The size of `%s', as computed by sizeof." % type_name)
+            return size
+        else:
+            context.Display("no\n")
+            _LogFailed(context, src, st)
+            return 0
+
+    return 0
+
+def CheckDeclaration(context, symbol, includes = None, language = None):
+    """Checks whether symbol is declared.
+
+    Use the same test as autoconf, that is test whether the symbol is defined
+    as a macro or can be used as an r-value.
+
+    Arguments:
+        symbol : str
+            the symbol to check
+        includes : str
+            Optional "header" can be defined to include a header file.
+        language : str
+            only C and C++ supported.
+
+    Returns:
+        status : bool
+            True if the check failed, False if succeeded."""
+    
+    # Include "confdefs.h" first, so that the header can use HAVE_HEADER_H.
+    if context.headerfilename:
+        includetext = '#include "%s"' % context.headerfilename
+    else:
+        includetext = ''
+
+    if not includes:
+        includes = ""
+
+    lang, suffix, msg = _lang2suffix(language)
+    if msg:
+        context.Display("Cannot check for declaration %s: %s\n" % (symbol, msg))
+        return msg
+
+    src = includetext + includes 
+    context.Display('Checking whether %s is declared... ' % symbol)
+
+    src = src + r"""
+int main()
+{
+#ifndef %s
+    (void) %s;
+#endif
+    ;
+    return 0;
+}
+""" % (symbol, symbol)
+
+    st = context.CompileProg(src, suffix)
+    _YesNoResult(context, st, "HAVE_DECL_" + symbol, src,
+                 "Set to 1 if %s is defined." % symbol)
+    return st
+
+def CheckLib(context, libs, func_name = None, header = None,
+             extra_libs = None, call = None, language = None, autoadd = 1,
+             append = True):
+    """
+    Configure check for a C or C++ libraries "libs".  Searches through
+    the list of libraries, until one is found where the test succeeds.
+    Tests if "func_name" or "call" exists in the library.  Note: if it exists
+    in another library the test succeeds anyway!
+    Optional "header" can be defined to include a header file.  If not given a
+    default prototype for "func_name" is added.
+    Optional "extra_libs" is a list of library names to be added after
+    "lib_name" in the build command.  To be used for libraries that "lib_name"
+    depends on.
+    Optional "call" replaces the call to "func_name" in the test code.  It must
+    consist of complete C statements, including a trailing ";".
+    Both "func_name" and "call" arguments are optional, and in that case, just
+    linking against the libs is tested.
+    "language" should be "C" or "C++" and is used to select the compiler.
+    Default is "C".
+    Note that this uses the current value of compiler and linker flags, make
+    sure $CFLAGS, $CPPFLAGS and $LIBS are set correctly.
+    Returns an empty string for success, an error message for failure.
+    """
+    # Include "confdefs.h" first, so that the header can use HAVE_HEADER_H.
+    if context.headerfilename:
+        includetext = '#include "%s"' % context.headerfilename
+    else:
+        includetext = ''
+    if not header:
+        header = ""
+
+    text = """
+%s
+%s""" % (includetext, header)
+
+    # Add a function declaration if needed.
+    if func_name and func_name != "main":
+        if not header:
+            text = text + """
+#ifdef __cplusplus
+extern "C"
+#endif
+char %s();
+""" % func_name
+
+        # The actual test code.
+        if not call:
+            call = "%s();" % func_name
+
+    # if no function to test, leave main() blank
+    text = text + """
+int
+main() {
+  %s
+return 0;
+}
+""" % (call or "")
+
+    if call:
+        i = call.find("\n")
+        if i > 0:
+            calltext = call[:i] + ".."
+        elif call[-1] == ';':
+            calltext = call[:-1]
+        else:
+            calltext = call
+
+    for lib_name in libs:
+
+        lang, suffix, msg = _lang2suffix(language)
+        if msg:
+            context.Display("Cannot check for library %s: %s\n" % (lib_name, msg))
+            return msg
+
+        # if a function was specified to run in main(), say it
+        if call:
+                context.Display("Checking for %s in %s library %s... "
+                                % (calltext, lang, lib_name))
+        # otherwise, just say the name of library and language
+        else:
+                context.Display("Checking for %s library %s... "
+                                % (lang, lib_name))
+
+        if lib_name:
+            l = [ lib_name ]
+            if extra_libs:
+                l.extend(extra_libs)
+            if append:
+                oldLIBS = context.AppendLIBS(l)
+            else:
+                oldLIBS = context.PrependLIBS(l)
+            sym = "HAVE_LIB" + lib_name
+        else:
+            oldLIBS = -1
+            sym = None
+
+        ret = context.BuildProg(text, suffix)
+
+        _YesNoResult(context, ret, sym, text,
+                     "Define to 1 if you have the `%s' library." % lib_name)
+        if oldLIBS != -1 and (ret or not autoadd):
+            context.SetLIBS(oldLIBS)
+            
+        if not ret:
+            return ret
+
+    return ret
+
+def CheckProg(context, prog_name):
+    """
+    Configure check for a specific program.
+
+    Check whether program prog_name exists in path.  If it is found,
+    returns the path for it, otherwise returns None.
+    """
+    context.Display("Checking whether %s program exists..." % prog_name)
+    path = context.env.WhereIs(prog_name)
+    if path:
+        context.Display(path + "\n")
+    else:
+        context.Display("no\n")
+    return path
+
+
+#
+# END OF PUBLIC FUNCTIONS
+#
+
+def _YesNoResult(context, ret, key, text, comment = None):
+    """
+    Handle the result of a test with a "yes" or "no" result.
+
+    :Parameters:
+      - `ret` is the return value: empty if OK, error message when not.
+      - `key` is the name of the symbol to be defined (HAVE_foo).
+      - `text` is the source code of the program used for testing.
+      - `comment` is the C comment to add above the line defining the symbol (the comment is automatically put inside a /\* \*/). If None, no comment is added.
+    """
+    if key:
+        _Have(context, key, not ret, comment)
+    if ret:
+        context.Display("no\n")
+        _LogFailed(context, text, ret)
+    else:
+        context.Display("yes\n")
+
+
+def _Have(context, key, have, comment = None):
+    """
+    Store result of a test in context.havedict and context.headerfilename.
+
+    :Parameters:
+      - `key` - is a "HAVE_abc" name.  It is turned into all CAPITALS and non-alphanumerics are replaced by an underscore.
+      - `have`   - value as it should appear in the header file, include quotes when desired and escape special characters!
+      - `comment` is the C comment to add above the line defining the symbol (the comment is automatically put inside a /\* \*/). If None, no comment is added.
+
+
+    The value of "have" can be:
+      - 1      - Feature is defined, add "#define key".
+      - 0      - Feature is not defined, add "/\* #undef key \*/". Adding "undef" is what autoconf does.  Not useful for the compiler, but it shows that the test was done.
+      - number - Feature is defined to this number "#define key have". Doesn't work for 0 or 1, use a string then.
+      - string - Feature is defined to this string "#define key have".
+
+
+    """
+    key_up = key.upper()
+    key_up = re.sub('[^A-Z0-9_]', '_', key_up)
+    context.havedict[key_up] = have
+    if have == 1:
+        line = "#define %s 1\n" % key_up
+    elif have == 0:
+        line = "/* #undef %s */\n" % key_up
+    elif isinstance(have, int):
+        line = "#define %s %d\n" % (key_up, have)
+    else:
+        line = "#define %s %s\n" % (key_up, str(have))
+    
+    if comment is not None:
+        lines = "\n/* %s */\n" % comment + line
+    else:
+        lines = "\n" + line
+
+    if context.headerfilename:
+        f = open(context.headerfilename, "a")
+        f.write(lines)
+        f.close()
+    elif hasattr(context,'config_h'):
+        context.config_h = context.config_h + lines
+
+
+def _LogFailed(context, text, msg):
+    """
+    Write to the log about a failed program.
+    Add line numbers, so that error messages can be understood.
+    """
+    if LogInputFiles:
+        context.Log("Failed program was:\n")
+        lines = text.split('\n')
+        if len(lines) and lines[-1] == '':
+            lines = lines[:-1]              # remove trailing empty line
+        n = 1
+        for line in lines:
+            context.Log("%d: %s\n" % (n, line))
+            n = n + 1
+    if LogErrorMessages:
+        context.Log("Error message: %s\n" % msg)
+
+
+def _lang2suffix(lang):
+    """
+    Convert a language name to a suffix.
+    When "lang" is empty or None C is assumed.
+    Returns a tuple (lang, suffix, None) when it works.
+    For an unrecognized language returns (None, None, msg).
+
+    Where:
+      - lang   = the unified language name
+      - suffix = the suffix, including the leading dot
+      - msg    = an error message
+    """
+    if not lang or lang in ["C", "c"]:
+        return ("C", ".c", None)
+    if lang in ["c++", "C++", "cpp", "CXX", "cxx"]:
+        return ("C++", ".cpp", None)
+
+    return None, None, "Unsupported language: %s" % lang
+
+
+# vim: set sw=4 et sts=4 tw=79 fo+=l:
+
+# Local Variables:
+# tab-width:4
+# indent-tabs-mode:nil
+# End:
+# vim: set expandtab tabstop=4 shiftwidth=4: