diff options
| author | Steven Knight <knight@baldmt.com> | 2007-08-17 03:17:04 (GMT) |
|---|---|---|
| committer | Steven Knight <knight@baldmt.com> | 2007-08-17 03:17:04 (GMT) |
| commit | 8cb34cccc26935bce5d07ed3f51cc29fbbd1ab03 (patch) | |
| tree | 7bc281e44fe45cae35656e0e457fef8f308fbb7b /doc/user/troubleshoot.xml | |
| parent | 5b4b4c6e5384712ab1835bdcf8beea09611b6e62 (diff) | |
| download | SCons-8cb34cccc26935bce5d07ed3f51cc29fbbd1ab03.zip SCons-8cb34cccc26935bce5d07ed3f51cc29fbbd1ab03.tar.gz SCons-8cb34cccc26935bce5d07ed3f51cc29fbbd1ab03.tar.bz2 | |
Merged revisions 2136-2200,2202-2290,2292-2301 via svnmerge from
http://scons.tigris.org/svn/scons/branches/core
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r2145 | stevenknight | 2007-07-17 09:15:12 -0500 (Tue, 17 Jul 2007) | 3 lines
Don't put null strings (from variable expansion) in a path list.
(They get turned into the current directory on later expansion.)
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r2146 | stevenknight | 2007-07-17 10:47:39 -0500 (Tue, 17 Jul 2007) | 3 lines
Add support for optional arguments on command-line long options
by specifying nargs='?'.
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r2149 | stevenknight | 2007-07-17 15:22:24 -0500 (Tue, 17 Jul 2007) | 2 lines
Remove left-over Optik mentions.
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r2150 | stevenknight | 2007-07-17 15:39:34 -0500 (Tue, 17 Jul 2007) | 4 lines
Add a $SWIGPATH variable for finding SWIG dependencies, with
$SWIGINC{PREFIX,SUFFIX} for adding them to the command line.
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r2154 | stevenknight | 2007-07-18 20:05:31 -0500 (Wed, 18 Jul 2007) | 2 lines
Fix variable misspellings in the doc added for $SWIGOUTPUT.
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r2155 | stevenknight | 2007-07-18 20:07:28 -0500 (Wed, 18 Jul 2007) | 2 lines
Add the Python eggs info file to the RPM packaging build.
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r2156 | stevenknight | 2007-07-18 20:15:08 -0500 (Wed, 18 Jul 2007) | 2 lines
Convert documentation from DocBook SGML to XML.
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r2158 | stevenknight | 2007-07-19 17:16:19 -0500 (Thu, 19 Jul 2007) | 3 lines
Conditionally add the .egg-info the RPM file list only if the distutils
in the version of Python that rpmbuild will execute knows about them.
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r2161 | stevenknight | 2007-07-19 19:12:29 -0500 (Thu, 19 Jul 2007) | 5 lines
Capture a test case (contributed by Tilo Prutz) where instantiation of
a private class causes javac to generate an additional anonymous inner
class file. (No solution yet, but there's no sense throwing away the
preparatory work.)
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r2162 | stevenknight | 2007-07-20 11:29:56 -0500 (Fri, 20 Jul 2007) | 3 lines
Support passing a list of .java files as source to the Java() builder.
(Leanid Nazdrynau)
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r2163 | garyo | 2007-07-20 12:00:35 -0500 (Fri, 20 Jul 2007) | 1 line
Fixed cut-n-paste error in Touch factory method doc in users guide.
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r2167 | stevenknight | 2007-07-21 22:59:40 -0500 (Sat, 21 Jul 2007) | 2 lines
Don't execute the SWIGOUTDIR test if swig isn't installed.
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r2168 | stevenknight | 2007-07-21 23:14:17 -0500 (Sat, 21 Jul 2007) | 2 lines
Fix the test's ability to run under a path name containing spaces.
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r2171 | stevenknight | 2007-07-24 15:54:41 -0500 (Tue, 24 Jul 2007) | 2 lines
Handle white space in key file names in the packaging build.
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r2172 | stevenknight | 2007-07-24 21:41:15 -0500 (Tue, 24 Jul 2007) | 2 lines
More efficient copying of construction environments.
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r2173 | stevenknight | 2007-07-25 10:56:02 -0500 (Wed, 25 Jul 2007) | 2 lines
Update the SCons build for Subversion and general clean-up.
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r2174 | stevenknight | 2007-07-25 11:35:16 -0500 (Wed, 25 Jul 2007) | 3 lines
Suppress the [brackets] around a node in the --tree=prune output if
the node is a source.
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r2175 | stevenknight | 2007-07-25 12:52:18 -0500 (Wed, 25 Jul 2007) | 3 lines
Commonize the skip_test() method and make its behavior configurable
via a TESTCOMMON_PASS_SKIPS environment variable.
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r2178 | stevenknight | 2007-07-25 21:43:47 -0500 (Wed, 25 Jul 2007) | 3 lines
Add $JAVACLASSPATH and $JAVASOURCEPATH construction variables. (Leanid
Nazdrynau)
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r2182 | stevenknight | 2007-07-30 12:10:20 -0500 (Mon, 30 Jul 2007) | 3 lines
Refactor Builder suffix-adjusting into its own method, so we can
(potentially) re-use it for Builders with attached source Builders.
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r2183 | stevenknight | 2007-07-30 14:51:53 -0500 (Mon, 30 Jul 2007) | 2 lines
More efficient source-builder suffix matching.
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r2184 | stevenknight | 2007-07-30 16:01:42 -0500 (Mon, 30 Jul 2007) | 4 lines
Encapsulate initialization of the default FS object by an accessor
function in SCons.Node.FS. (This also gets rid of an unnecessary
reference to SCons.Node.FS.default_fs in the LaTeX scanner.)
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r2193 | stevenknight | 2007-07-30 18:24:07 -0500 (Mon, 30 Jul 2007) | 3 lines
Fix interpretation of source arguments that have no suffix when the
called Builder has both a src_suffix and a src_builder.
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r2194 | stevenknight | 2007-07-31 10:25:31 -0500 (Tue, 31 Jul 2007) | 2 lines
Increase the number of tries for random output from three to ten.
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r2195 | stevenknight | 2007-07-31 10:52:28 -0500 (Tue, 31 Jul 2007) | 3 lines
Skip the test gracefully if the zipfile module can't read the file it
just wrote (which is the case for Python 2.1 on 64-bit systems).
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r2196 | stevenknight | 2007-07-31 13:06:21 -0500 (Tue, 31 Jul 2007) | 2 lines
Move the "import zipfile" so it doesn't fail on Python <= 2.0.
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r2197 | stevenknight | 2007-07-31 14:51:50 -0500 (Tue, 31 Jul 2007) | 3 lines
Commonize initialization of the various Java builders so they can be
hooked up into a multi-stage Builder chain. (Leanid Nazdrynau)
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r2198 | stevenknight | 2007-07-31 16:15:18 -0500 (Tue, 31 Jul 2007) | 3 lines
Fix use of ${TARGET.dir} and ${SOURCE.dir} expansions in $FORTRANMODDIR
$JARCHDIR, $JARFLAGS, $LEXFLAGS, $SWIGFLAGS, $SWIGOUTDIR and $YACCFLAGS.
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r2199 | stevenknight | 2007-07-31 16:25:48 -0500 (Tue, 31 Jul 2007) | 2 lines
Remove left-over Trace() call.
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r2202 | stevenknight | 2007-08-01 12:31:48 -0500 (Wed, 01 Aug 2007) | 3 lines
Bail out via test.skip_test() if wix ("candle") isn't found.
Put the main body of code flush left instead of under an if: block.
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r2203 | stevenknight | 2007-08-01 15:35:55 -0500 (Wed, 01 Aug 2007) | 5 lines
Fix Tool.packaging.rpm.package() so it doesn't always overwrite
$RPMFLAGS with -ta.
Set --buildroot in RPM packaging tests so they don't overwrite
each other when run simultaneously.
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r2204 | stevenknight | 2007-08-01 15:37:36 -0500 (Wed, 01 Aug 2007) | 2 lines
Fix a nested scope issue with the internal build_sources() function.
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r2205 | stevenknight | 2007-08-01 15:46:08 -0500 (Wed, 01 Aug 2007) | 5 lines
Normalize (X out) the CreationDate field inside embedded, compressed
PostScript streams within the generated PDF files. Also normalize
preceding Length field, since compression length is affected by different
patterns of input, including the variable CreationDate value.
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r2211 | stevenknight | 2007-08-02 08:52:06 -0500 (Thu, 02 Aug 2007) | 2 lines
Add the new modules from branches/packaging to the SCons packaging build.
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r2212 | stevenknight | 2007-08-02 19:59:01 -0500 (Thu, 02 Aug 2007) | 2 lines
Fix the JAVACLASSPATH test when javah isn't on the default $PATH.
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r2214 | stevenknight | 2007-08-03 15:05:21 -0500 (Fri, 03 Aug 2007) | 4 lines
Hook up the Java builders into a multi-step chain underneath a Java()
pseudo-builder (wrapper) that examines its arguments and calls the
appropriate underlying file-or-dir builder.
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r2215 | stevenknight | 2007-08-03 15:49:58 -0500 (Fri, 03 Aug 2007) | 2 lines
Fix for old Python versions: use apply() instead of *args, **kw.
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r2216 | stevenknight | 2007-08-03 16:49:31 -0500 (Fri, 03 Aug 2007) | 2 lines
Hook up the SWIG builder as a source builder for .java files.
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r2217 | stevenknight | 2007-08-03 17:28:19 -0500 (Fri, 03 Aug 2007) | 2 lines
Don't use .endswith(), which didn't appear until later Python versions.
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r2218 | stevenknight | 2007-08-03 17:29:38 -0500 (Fri, 03 Aug 2007) | 2 lines
Replace tabs with spaces.
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r2219 | stevenknight | 2007-08-04 08:06:23 -0500 (Sat, 04 Aug 2007) | 3 lines
Initialize a loop-invariant lambda for matching .java suffixes outside
the loop.
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r2220 | stevenknight | 2007-08-07 15:06:13 -0500 (Tue, 07 Aug 2007) | 2 lines
Refactor parallel class-generation loops into one.
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r2221 | stevenknight | 2007-08-07 16:04:06 -0500 (Tue, 07 Aug 2007) | 5 lines
Have the Java multi-step builder test actually check for generated files,
and fix the generation of .java and .class file names, and interaction
with the SWIG builder, so that the files are generated in the correct
place.
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r2222 | stevenknight | 2007-08-07 16:45:05 -0500 (Tue, 07 Aug 2007) | 3 lines
Fix dependencies on SWIG-generated .java files so they don't have to
be built in multiple passes.
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r2226 | stevenknight | 2007-08-07 18:00:22 -0500 (Tue, 07 Aug 2007) | 2 lines
Fix SWIG when used with BuildDir().
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r2227 | stevenknight | 2007-08-07 22:15:55 -0500 (Tue, 07 Aug 2007) | 5 lines
User's guide updates:
- Make the multiple files example match its text.
- Expand a truncated sentence about being able to use Python function actions
in the Command() Builder.
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r2228 | stevenknight | 2007-08-07 23:25:18 -0500 (Tue, 07 Aug 2007) | 3 lines
Don't generate an error if a #include file matches a same-named
directory in $CPPPATH (or $FORTRANPATH, etc.).
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r2229 | stevenknight | 2007-08-07 23:40:00 -0500 (Tue, 07 Aug 2007) | 2 lines
Fix a code example. (Gary Oberbrunner)
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r2230 | stevenknight | 2007-08-08 00:05:43 -0500 (Wed, 08 Aug 2007) | 3 lines
Capture a test case to make sure AddPostAction() doesn't interfere
with normal linking. (Matt Doar, Gary Oberbrunner)
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r2233 | stevenknight | 2007-08-08 14:15:44 -0500 (Wed, 08 Aug 2007) | 2 lines
Fix documentation typo in a construction variable cross-reference.
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r2234 | stevenknight | 2007-08-08 17:03:25 -0500 (Wed, 08 Aug 2007) | 2 lines
Changes to SCons packaging to support checkpoint releases.
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r2235 | stevenknight | 2007-08-09 10:10:01 -0500 (Thu, 09 Aug 2007) | 2 lines
Sidestep false negatives on heavily loaded systems.
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r2236 | garyo | 2007-08-09 11:16:26 -0500 (Thu, 09 Aug 2007) | 1 line
Allow unpackaged files (e.g. *.pyo) to exist in the build dir without being packaged in the RPM. Without this, on some systems the rpmbuild may error out.
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r2237 | stevenknight | 2007-08-09 11:27:56 -0500 (Thu, 09 Aug 2007) | 5 lines
Fix test/SWIG/build-dir.py so it works on old Python versions without
distutils.sysconfig.
Instead of just cutting-and-pasting initialization code from other
SWIG tests, centralize it in some new TestSCons methods.
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r2238 | garyo | 2007-08-09 11:30:58 -0500 (Thu, 09 Aug 2007) | 1 line
Use docbook 4.3 instead of 4.4 for the XML doctype since some older(?) jade parsers can't handle new 4-byte Unicode chars in the 4.4 version of isogrk4.ent.
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r2240 | stevenknight | 2007-08-09 16:35:06 -0500 (Thu, 09 Aug 2007) | 2 lines
User's Guide updates (post packaging changes).
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r2243 | stevenknight | 2007-08-10 10:31:51 -0500 (Fri, 10 Aug 2007) | 3 lines
Fix the User's Guide build to use openjade, and to accomodate a change
in the name of the main generated file (book1.html => index.html).
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r2245 | stevenknight | 2007-08-10 11:09:16 -0500 (Fri, 10 Aug 2007) | 2 lines
Update the {CHANGES,RELEASE}.txt datestamp lines.
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r2253 | stevenknight | 2007-08-10 16:21:54 -0500 (Fri, 10 Aug 2007) | 2 lines
Fix the wix Tool module's ability to handle null entries in $PATH.
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r2261 | stevenknight | 2007-08-11 23:08:12 -0500 (Sat, 11 Aug 2007) | 3 lines
Remove unnecessary files (.svnt/*, .{ae,cvs}ignore, www/*) from the
scons-src packages.
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r2262 | stevenknight | 2007-08-11 23:24:49 -0500 (Sat, 11 Aug 2007) | 2 lines
Add missing __revision__ lines.
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r2263 | stevenknight | 2007-08-11 23:33:42 -0500 (Sat, 11 Aug 2007) | 2 lines
Skip the test if the MANIFEST file hasn't been built.
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r2264 | stevenknight | 2007-08-11 23:36:30 -0500 (Sat, 11 Aug 2007) | 2 lines
Add recent compatibility modules to the relevant exceptions lists.
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r2265 | stevenknight | 2007-08-11 23:39:00 -0500 (Sat, 11 Aug 2007) | 3 lines
Update __VERSION__ strings in the QMTest/*.py modules, so that packaging
tests (src/test_*.py) will pass after builds of checkpoint releases.
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r2266 | stevenknight | 2007-08-12 07:36:19 -0500 (Sun, 12 Aug 2007) | 2 lines
Add a comment about why we construct the __VERSION__ string at run time.
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r2267 | stevenknight | 2007-08-12 07:42:30 -0500 (Sun, 12 Aug 2007) | 2 lines
Avoid reading the MANIFEST file twice. (Courtesy review by Greg Noel.)
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r2268 | stevenknight | 2007-08-12 08:14:53 -0500 (Sun, 12 Aug 2007) | 3 lines
Shift Install() and InstallAs() from being documented as functions
to being documented as Builders.
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r2269 | garyo | 2007-08-13 08:49:52 -0500 (Mon, 13 Aug 2007) | 1 line
Tests: Skip some more Java tests if javac is not installed on the test machine so they don't get marked as failing.
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r2270 | garyo | 2007-08-13 11:09:39 -0500 (Mon, 13 Aug 2007) | 1 line
Fixed typo in test (shows up on non-Linux platforms).
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r2271 | garyo | 2007-08-13 14:09:05 -0500 (Mon, 13 Aug 2007) | 4 lines
Test portability fixes for Darwin/OSX and IRIX.
This does not make all the tests pass on those OSes,
but it takes care of some of the more obvious errors that
I have time for right now. More to come.
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r2272 | stevenknight | 2007-08-13 15:33:29 -0500 (Mon, 13 Aug 2007) | 2 lines
Tab => space fix.
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r2273 | stevenknight | 2007-08-13 15:33:52 -0500 (Mon, 13 Aug 2007) | 2 lines
Test for swig, too, which is used to build from the .i file.
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r2277 | garyo | 2007-08-14 10:40:00 -0500 (Tue, 14 Aug 2007) | 8 lines
Test portability on IRIX: test/Actions/pre-post creates target file
before building target, then IRIX CC does not chmod +x afterwards.
I think this change is safe on all OSes.
test/AS/ml.py: I think this is only supposed to be run on win32
(not skipped only on win32); the sense of the skip test was backwards.
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r2278 | stevenknight | 2007-08-14 11:04:40 -0500 (Tue, 14 Aug 2007) | 2 lines
Add -tt when running tests, to catch inconsistent tab usage.
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r2279 | stevenknight | 2007-08-14 14:00:43 -0500 (Tue, 14 Aug 2007) | 2 lines
Minor refactor of logic in File.retrieve_from_cache().
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r2280 | stevenknight | 2007-08-15 01:11:40 -0500 (Wed, 15 Aug 2007) | 2 lines
Refactor CacheDir support into its own module.
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r2281 | stevenknight | 2007-08-15 07:24:51 -0500 (Wed, 15 Aug 2007) | 2 lines
Move the cachepath() method from FS.File to the CacheDir class.
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r2282 | stevenknight | 2007-08-15 08:31:34 -0500 (Wed, 15 Aug 2007) | 2 lines
Python 1.5.2 fix in the new Null class.
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r2283 | stevenknight | 2007-08-15 10:45:53 -0500 (Wed, 15 Aug 2007) | 5 lines
Refactor CacheDir unit tests to:
- restore functionality that was dropped in the transition;
- commonize creation of test Nodes and other (mock) objects
- separate CacheDir tests from tests of CacheDir through Node.FS.File.
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r2284 | stevenknight | 2007-08-15 11:46:38 -0500 (Wed, 15 Aug 2007) | 3 lines
Replace the Executor.Null.NullEnvironment object with a real Null object,
so it will absorb the CacheDir method calls as well.
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r2285 | stevenknight | 2007-08-15 11:52:57 -0500 (Wed, 15 Aug 2007) | 5 lines
Add a get_CacheDir() method to a construction environment, which will
be used to fetch per-environment CacheDir specifications. (Right now
all calls to it still just return the one attached to underlying default
FS object.)
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r2286 | stevenknight | 2007-08-15 15:15:46 -0500 (Wed, 15 Aug 2007) | 2 lines
Support per-construction-environment configuration of CacheDir().
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r2287 | stevenknight | 2007-08-15 15:33:04 -0500 (Wed, 15 Aug 2007) | 2 lines
Move the tests of CacheDir()-related command-line options into test/CacheDir.
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r2293 | stevenknight | 2007-08-16 11:14:49 -0500 (Thu, 16 Aug 2007) | 3 lines
Add the Package() builder description to the documentation build,
fixing the XML so that it will build.
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r2294 | stevenknight | 2007-08-16 12:51:19 -0500 (Thu, 16 Aug 2007) | 3 lines
Reorganize packaging documentation: alphabetize the variable definitions
(and function names), document Tag() as a function, not a builder.
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r2296 | stevenknight | 2007-08-16 12:55:01 -0500 (Thu, 16 Aug 2007) | 2 lines
Add a build command.
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r2300 | stevenknight | 2007-08-16 16:49:13 -0500 (Thu, 16 Aug 2007) | 2 lines
First cut at documenting packaging variables.
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r2301 | stevenknight | 2007-08-16 16:51:21 -0500 (Thu, 16 Aug 2007) | 3 lines
Construct the .src.rpm and .arch.rpm file names independnetly, not
by trying to massage one into the other.
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Diffstat (limited to 'doc/user/troubleshoot.xml')
| -rw-r--r-- | doc/user/troubleshoot.xml | 1232 |
1 files changed, 1232 insertions, 0 deletions
diff --git a/doc/user/troubleshoot.xml b/doc/user/troubleshoot.xml new file mode 100644 index 0000000..6ec6185 --- /dev/null +++ b/doc/user/troubleshoot.xml @@ -0,0 +1,1232 @@ +<!-- + + __COPYRIGHT__ + + 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. + +--> + + <para> + + The experience of configuring any + software build tool to build a large code base + usually, at some point, + involves trying to figure out why + the tool is behaving a certain way, + and how to get it to behave the way you want. + &SCons; is no different. + This appendix contains a number of + different ways in which you can + get some additional insight into &SCons;' behavior. + + </para> + + <para> + + Note that we're always interested in trying to + improve how you can troubleshoot configuration problems. + If you run into a problem that has + you scratching your head, + and which there just doesn't seem to be a good way to debug, + odds are pretty good that someone else will run into + the same problem, too. + If so, please let the SCons development team know + (preferably by filing a bug report + or feature request at our project pages at tigris.org) + so that we can use your feedback + to try to come up with a better way to help you, + and others, get the necessary insight into &SCons; behavior + to help identify and fix configuration issues. + + </para> + + <section> + <title>Why is That Target Being Rebuilt? the &debug-explain; Option</title> + + <para> + + Let's look at a simple example of + a misconfigured build + that causes a target to be rebuilt + every time &SCons; is run: + + </para> + + <programlisting> + # Intentionally misspell the output file name in the + # command used to create the file: + Command('file.out', 'file.in', 'cp $SOURCE file.oout') + </programlisting> + + <para> + + (Note to Windows users: The POSIX &cp; command + copies the first file named on the command line + to the second file. + In our example, it copies the &file_in; file + to the &file_out; file.) + + </para> + + <para> + + Now if we run &SCons; multiple times on this example, + we see that it re-runs the &cp; + command every time: + + </para> + + <screen> + % <userinput>scons -Q</userinput> + cp file.in file.oout + % <userinput>scons -Q</userinput> + cp file.in file.oout + % <userinput>scons -Q</userinput> + cp file.in file.oout + </screen> + + <para> + + In this example, + the underlying cause is obvious: + we've intentionally misspelled the output file name + in the &cp; command, + so the command doesn't actually + build the &file_out; file that we've told &SCons; to expect. + But if the problem weren't obvious, + it would be helpful + to specify the &debug-explain; option + on the command line + to have &SCons; tell us very specifically + why it's decided to rebuild the target: + + </para> + + <screen> + % <userinput>scons -Q --debug=explain</userinput> + scons: building `file.out' because it doesn't exist + cp file.in file.oout + </screen> + + <para> + + If this had been a more complicated example + involving a lot of build output, + having &SCons; tell us that + it's trying to rebuild the target file + because it doesn't exist + would be an important clue + that something was wrong with + the command that we invoked to build it. + + </para> + + <para> + + The &debug-explain; option also comes in handy + to help figure out what input file changed. + Given a simple configuration that builds + a program from three source files, + changing one of the source files + and rebuilding with the &debug-explain; + option shows very specifically + why &SCons; rebuilds the files that it does: + + </para> + + + + <screen> + % <userinput>scons -Q</userinput> + cc -o file1.o -c file1.c + cc -o file2.o -c file2.c + cc -o file3.o -c file3.c + cc -o prog file1.o file2.o file3.o + % <userinput>edit file2.c</userinput> + [CHANGE THE CONTENTS OF file2.c] + % <userinput>scons -Q --debug=explain</userinput> + scons: rebuilding `file2.o' because `file2.c' changed + cc -o file2.o -c file2.c + scons: rebuilding `prog' because `file2.o' changed + cc -o prog file1.o file2.o file3.o + </screen> + + <para> + + This becomes even more helpful + in identifying when a file is rebuilt + due to a change in an implicit dependency, + such as an incuded <filename>.h</filename> file. + If the <filename>file1.c</filename> + and <filename>file3.c</filename> files + in our example + both included a &hello_h; file, + then changing that included file + and re-running &SCons; with the &debug-explain; option + will pinpoint that it's the change to the included file + that starts the chain of rebuilds: + + </para> + + + + <screen> + % <userinput>scons -Q</userinput> + cc -o file1.o -c -I. file1.c + cc -o file2.o -c -I. file2.c + cc -o file3.o -c -I. file3.c + cc -o prog file1.o file2.o file3.o + % <userinput>edit hello.h</userinput> + [CHANGE THE CONTENTS OF hello.h] + % <userinput>scons -Q --debug=explain</userinput> + scons: rebuilding `file1.o' because `hello.h' changed + cc -o file1.o -c -I. file1.c + scons: rebuilding `file3.o' because `hello.h' changed + cc -o file3.o -c -I. file3.c + scons: rebuilding `prog' because: + `file1.o' changed + `file3.o' changed + cc -o prog file1.o file2.o file3.o + </screen> + + <para> + + (Note that the &debug-explain; option will only tell you + why &SCons; decided to rebuild necessary targets. + It does not tell you what files it examined + when deciding <emphasis>not</emphasis> + to rebuild a target file, + which is often a more valuable question to answer.) + + </para> + + </section> + + <section> + <title>What's in That Construction Environment? the &Dump; Method</title> + + <para> + + When you create a construction environment, + &SCons; populates it + with construction variables that are set up + for various compilers, linkers and utilities + that it finds on your system. + Although this is usually helpful and what you want, + it might be frustrating if &SCons; + doesn't set certain variables that you + expect to be sit. + In situations like this, + it's sometimes helpful to use the + construction environment &Dump; method + to print all or some of + the construction variables. + Note that the &Dump; method + <emphasis>returns</emphasis> + the representation of the variables + in the environment + for you to print (or otherwise manipulate): + + </para> + + <programlisting> + env = Environment() + print env.Dump() + </programlisting> + + <para> + + On a POSIX system with gcc installed, + this might generate: + + </para> + + <screen> + % <userinput>scons</userinput> + scons: Reading SConscript files ... + { 'BUILDERS': {'InstallAs': <function InstallAsBuilderWrapper at 0xb23a28>, 'Install': <function InstallBuilderWrapper at 0xb1b7d0>}, + 'CONFIGUREDIR': '#/.sconf_temp', + 'CONFIGURELOG': '#/config.log', + 'CPPSUFFIXES': [ '.c', + '.C', + '.cxx', + '.cpp', + '.c++', + '.cc', + '.h', + '.H', + '.hxx', + '.hpp', + '.hh', + '.F', + '.fpp', + '.FPP', + '.m', + '.mm', + '.S', + '.spp', + '.SPP'], + 'DSUFFIXES': ['.d'], + 'Dir': <SCons.Defaults.Variable_Method_Caller instance at 0xa1eb48>, + 'Dirs': <SCons.Defaults.Variable_Method_Caller instance at 0xa1eb90>, + 'ENV': {'PATH': '/usr/local/bin:/opt/bin:/bin:/usr/bin'}, + 'ESCAPE': <function escape at 0xb1fa28>, + 'File': <SCons.Defaults.Variable_Method_Caller instance at 0xa1ebd8>, + 'IDLSUFFIXES': ['.idl', '.IDL'], + 'INSTALL': <function copyFunc at 0xb23aa0>, + 'LATEXSUFFIXES': ['.tex', '.ltx', '.latex'], + 'LIBPREFIX': 'lib', + 'LIBPREFIXES': '$LIBPREFIX', + 'LIBSUFFIX': '.a', + 'LIBSUFFIXES': ['$LIBSUFFIX', '$SHLIBSUFFIX'], + 'MAXLINELENGTH': 128072, + 'OBJPREFIX': '', + 'OBJSUFFIX': '.o', + 'PLATFORM': 'posix', + 'PROGPREFIX': '', + 'PROGSUFFIX': '', + 'PSPAWN': <function piped_env_spawn at 0xb23230>, + 'RDirs': <SCons.Defaults.Variable_Method_Caller instance at 0xa1ec20>, + 'SCANNERS': [], + 'SHELL': 'sh', + 'SHLIBPREFIX': '$LIBPREFIX', + 'SHLIBSUFFIX': '.so', + 'SHOBJPREFIX': '$OBJPREFIX', + 'SHOBJSUFFIX': '$OBJSUFFIX', + 'SPAWN': <function spawnvpe_spawn at 0xb1f7d0>, + 'TEMPFILE': <class SCons.Platform.TempFileMunge at 0xa4e170>, + 'TEMPFILEPREFIX': '@', + 'TOOLS': ['install', 'install'], + '_CPPDEFFLAGS': '${_defines(CPPDEFPREFIX, CPPDEFINES, CPPDEFSUFFIX, __env__)}', + '_CPPINCFLAGS': '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)', + '_LIBDIRFLAGS': '$( ${_concat(LIBDIRPREFIX, LIBPATH, LIBDIRSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)', + '_LIBFLAGS': '${_concat(LIBLINKPREFIX, LIBS, LIBLINKSUFFIX, __env__)}', + '__RPATH': '$_RPATH', + '_concat': <function _concat at 0xa3d398>, + '_defines': <function _defines at 0xa3d500>, + '_stripixes': <function _stripixes at 0xa3d488>} + scons: done reading SConscript files. + scons: Building targets ... + scons: `.' is up to date. + scons: done building targets. + </screen> + + <para> + + On a Windows system with Visual C++ + the output might look like: + + </para> + + <screen> + C:\><userinput>scons</userinput> + scons: Reading SConscript files ... + { 'BUILDERS': {'RES': <SCons.Builder.BuilderBase instance at 0xb39518>, 'Object': <SCons.Builder.CompositeBuilder instance at 0xb4a710>, 'InstallAs': <function InstallAsBuilderWrapper at 0xb45c08>, 'PCH': <SCons.Builder.BuilderBase instance at 0xb1cef0>, 'Install': <function InstallBuilderWrapper at 0xb1b7d0>, 'SharedObject': <SCons.Builder.CompositeBuilder instance at 0xb4aa28>, 'StaticObject': <SCons.Builder.CompositeBuilder instance at 0xb4a710>}, + 'CC': 'cl', + 'CCCOM': <SCons.Action.FunctionAction instance at 0xb4c290>, + 'CCCOMFLAGS': '$CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS /c $SOURCES /Fo$TARGET $CCPCHFLAGS $CCPDBFLAGS', + 'CCFLAGS': ['/nologo'], + 'CCPCHFLAGS': ['${(PCH and "/Yu%s /Fp%s"%(PCHSTOP or "",File(PCH))) or ""}'], + 'CCPDBFLAGS': ['${(PDB and "/Z7") or ""}'], + 'CFILESUFFIX': '.c', + 'CFLAGS': [], + 'CONFIGUREDIR': '#/.sconf_temp', + 'CONFIGURELOG': '#/config.log', + 'CPPDEFPREFIX': '/D', + 'CPPDEFSUFFIX': '', + 'CPPSUFFIXES': [ '.c', + '.C', + '.cxx', + '.cpp', + '.c++', + '.cc', + '.h', + '.H', + '.hxx', + '.hpp', + '.hh', + '.F', + '.fpp', + '.FPP', + '.m', + '.mm', + '.S', + '.spp', + '.SPP'], + 'CXX': '$CC', + 'CXXCOM': '$CXX $CXXFLAGS $CCCOMFLAGS', + 'CXXFILESUFFIX': '.cc', + 'CXXFLAGS': ['$CCFLAGS', '$(', '/TP', '$)'], + 'DSUFFIXES': ['.d'], + 'Dir': <SCons.Defaults.Variable_Method_Caller instance at 0xa1eb48>, + 'Dirs': <SCons.Defaults.Variable_Method_Caller instance at 0xa1eb90>, + 'ENV': { 'INCLUDE': 'C:\\Program Files\\Microsoft Visual Studio/VC98\\include', + 'LIB': 'C:\\Program Files\\Microsoft Visual Studio/VC98\\lib', + 'PATH': 'C:\\Program Files\\Microsoft Visual Studio\\Common\\tools\\WIN95;C:\\Program Files\\Microsoft Visual Studio\\Common\\MSDev98\\bin;C:\\Program Files\\Microsoft Visual Studio\\Common\\tools;C:\\Program Files\\Microsoft Visual Studio/VC98\\bin', + 'PATHEXT': '.COM;.EXE;.BAT;.CMD', + 'SystemRoot': 'C:/WINDOWS'}, + 'ESCAPE': <function escape at 0xb24848>, + 'File': <SCons.Defaults.Variable_Method_Caller instance at 0xa1ebd8>, + 'IDLSUFFIXES': ['.idl', '.IDL'], + 'INCPREFIX': '/I', + 'INCSUFFIX': '', + 'INSTALL': <function copyFunc at 0xb45c80>, + 'LATEXSUFFIXES': ['.tex', '.ltx', '.latex'], + 'LIBPREFIX': '', + 'LIBPREFIXES': ['$LIBPREFIX'], + 'LIBSUFFIX': '.lib', + 'LIBSUFFIXES': ['$LIBSUFFIX'], + 'MAXLINELENGTH': 2048, + 'MSVS': {'VERSION': '6.0', 'VERSIONS': ['6.0']}, + 'MSVS_VERSION': '6.0', + 'OBJPREFIX': '', + 'OBJSUFFIX': '.obj', + 'PCHCOM': '$CXX $CXXFLAGS $CPPFLAGS $_CPPDEFFLAGS $_CPPINCFLAGS /c $SOURCES /Fo${TARGETS[1]} /Yc$PCHSTOP /Fp${TARGETS[0]} $CCPDBFLAGS $PCHPDBFLAGS', + 'PCHPDBFLAGS': ['${(PDB and "/Yd") or ""}'], + 'PLATFORM': 'win32', + 'PROGPREFIX': '', + 'PROGSUFFIX': '.exe', + 'PSPAWN': <function piped_spawn at 0xb20488>, + 'RC': 'rc', + 'RCCOM': '$RC $_CPPDEFFLAGS $_CPPINCFLAGS $RCFLAGS /fo$TARGET $SOURCES', + 'RCFLAGS': [], + 'RDirs': <SCons.Defaults.Variable_Method_Caller instance at 0xa1ec20>, + 'SCANNERS': [], + 'SHCC': '$CC', + 'SHCCCOM': <SCons.Action.FunctionAction instance at 0xb4c320>, + 'SHCCFLAGS': ['$CCFLAGS'], + 'SHCFLAGS': ['$CFLAGS'], + 'SHCXX': '$CXX', + 'SHCXXCOM': '$SHCXX $SHCXXFLAGS $CCCOMFLAGS', + 'SHCXXFLAGS': ['$CXXFLAGS'], + 'SHELL': None, + 'SHLIBPREFIX': '', + 'SHLIBSUFFIX': '.dll', + 'SHOBJPREFIX': '$OBJPREFIX', + 'SHOBJSUFFIX': '$OBJSUFFIX', + 'SPAWN': <function spawn at 0xb247d0>, + 'STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME': 1, + 'TEMPFILE': <class SCons.Platform.TempFileMunge at 0xa4e170>, + 'TEMPFILEPREFIX': '@', + 'TOOLS': ['msvc', 'install', 'install'], + '_CPPDEFFLAGS': '${_defines(CPPDEFPREFIX, CPPDEFINES, CPPDEFSUFFIX, __env__)}', + '_CPPINCFLAGS': '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)', + '_LIBDIRFLAGS': '$( ${_concat(LIBDIRPREFIX, LIBPATH, LIBDIRSUFFIX, __env__, RDirs, TARGET, SOURCE)} $)', + '_LIBFLAGS': '${_concat(LIBLINKPREFIX, LIBS, LIBLINKSUFFIX, __env__)}', + '_concat': <function _concat at 0xa3d398>, + '_defines': <function _defines at 0xa3d500>, + '_stripixes': <function _stripixes at 0xa3d488>} + scons: done reading SConscript files. + scons: Building targets ... + scons: `.' is up to date. + scons: done building targets. + </screen> + + <para> + + The construction environments in these examples have + actually been restricted to just gcc and Visual C++, + respectively. + In a real-life situation, + the construction environments will + likely contain a great many more variables. + + </para> + + <para> + + To make it easier to see just what you're + interested in, + the &Dump; method allows you to + specify a specific constrcution variable + that you want to disply. + For example, + it's not unusual to want to verify + the external environment used to execute build commands, + to make sure that the PATH and other + environment variables are set up the way they should be. + You can do this as follows: + + </para> + + <programlisting> + env = Environment() + print env.Dump('ENV') + </programlisting> + + <para> + + Which might display the following when executed on a POSIX system: + + </para> + + <screen> + % <userinput>scons</userinput> + scons: Reading SConscript files ... + {'PATH': '/usr/local/bin:/opt/bin:/bin:/usr/bin'} + scons: done reading SConscript files. + scons: Building targets ... + scons: `.' is up to date. + scons: done building targets. + </screen> + + <para> + + And the following when executed on a Windows system: + + </para> + + <screen> + C:\><userinput>scons</userinput> + scons: Reading SConscript files ... + { 'INCLUDE': 'C:\\Program Files\\Microsoft Visual Studio/VC98\\include', + 'LIB': 'C:\\Program Files\\Microsoft Visual Studio/VC98\\lib', + 'PATH': 'C:\\Program Files\\Microsoft Visual Studio\\Common\\tools\\WIN95;C:\\Program Files\\Microsoft Visual Studio\\Common\\MSDev98\\bin;C:\\Program Files\\Microsoft Visual Studio\\Common\\tools;C:\\Program Files\\Microsoft Visual Studio/VC98\\bin', + 'PATHEXT': '.COM;.EXE;.BAT;.CMD', + 'SystemRoot': 'C:/WINDOWS'} + scons: done reading SConscript files. + scons: Building targets ... + scons: `.' is up to date. + scons: done building targets. + </screen> + + </section> + + <section> + + <title>What Dependencies Does &SCons; Know About? the &tree; Option</title> + + <para> + + Sometimes the best way to try to figure out what + &SCons; is doing is simply to take a look at the + dependency graph that it constructs + based on your &SConscript; files. + The <literal>--tree</literal> option + will display all or part of the + &SCons; dependency graph in an + "ASCII art" graphical format + that shows the dependency hierarchy. + + </para> + + <para> + + For example, given the following input &SConstruct; file: + + </para> + + <programlisting> + env = Environment(CPPPATH = ['.']) + env.Program('prog', ['f1.c', 'f2.c', 'f3.c']) + </programlisting> + + <para> + + Running &SCons; with the <literal>--tree=all</literal> + option yields: + + </para> + + <screen> + % <userinput>scons -Q --tree=all</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + cc -o prog f1.o f2.o f3.o + +-. + +-- + +-SConstruct + +-f1.c + +-f1.o + | +-f1.c + | +-inc.h + +-f2.c + +-f2.o + | +-f2.c + | +-inc.h + +-f3.c + +-f3.o + | +-f3.c + | +-inc.h + +-inc.h + +-prog + +-f1.o + | +-f1.c + | +-inc.h + +-f2.o + | +-f2.c + | +-inc.h + +-f3.o + +-f3.c + +-inc.h + </screen> + + <para> + + The tree will also be printed when the + <literal>-n</literal> (no execute) option is used, + which allows you to examine the dependency graph + for a configuration without actually + rebuilding anything in the tree. + + </para> + + <para> + + The <literal>--tree</literal> option only prints + the dependency graph for the specified targets + (or the default target(s) if none are specified on the command line). + So if you specify a target like <filename>f2.o</filename> + on the command line, + the <literal>--tree</literal> option will only + print the dependency graph for that file: + + </para> + + <screen> + % <userinput>scons -Q --tree=all f2.o</userinput> + cc -o f2.o -c -I. f2.c + +-f2.o + +-f2.c + +-inc.h + </screen> + + <para> + + This is, of course, useful for + restricting the output from a very large + build configuration to just a + portion in which you're interested. + Multiple targets are fine, + in which case a tree will be printed + for each specified target: + + </para> + + <screen> + % <userinput>scons -Q --tree=all f1.o f3.o</userinput> + cc -o f1.o -c -I. f1.c + +-f1.o + +-f1.c + +-inc.h + cc -o f3.o -c -I. f3.c + +-f3.o + +-f3.c + +-inc.h + </screen> + + <para> + + The <literal>status</literal> argument may be used + to tell &SCons; to print status information about + each file in the dependency graph: + + </para> + + <screen> + % <userinput>scons -Q --tree=status</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + cc -o prog f1.o f2.o f3.o + E = exists + R = exists in repository only + b = implicit builder + B = explicit builder + S = side effect + P = precious + A = always build + C = current + N = no clean + H = no cache + + [E b ]+-. + [ ] +-- + [E ] +-SConstruct + [E ] +-f1.c + [E B C ] +-f1.o + [E ] | +-f1.c + [E ] | +-inc.h + [E ] +-f2.c + [E B C ] +-f2.o + [E ] | +-f2.c + [E ] | +-inc.h + [E ] +-f3.c + [E B C ] +-f3.o + [E ] | +-f3.c + [E ] | +-inc.h + [E ] +-inc.h + [E B C ] +-prog + [E B C ] +-f1.o + [E ] | +-f1.c + [E ] | +-inc.h + [E B C ] +-f2.o + [E ] | +-f2.c + [E ] | +-inc.h + [E B C ] +-f3.o + [E ] +-f3.c + [E ] +-inc.h + </screen> + + <para> + + Note that <literal>--tree=all,status</literal> is equivalent; + the <literal>all</literal> + is assumed if only <literal>status</literal> is present. + As an alternative to <literal>all</literal>, + you can specify <literal>--tree=derived</literal> + to have &SCons; only print derived targets + in the tree output, + skipping source files + (like <filename>.c</filename> and <filename>.h</filename> files): + + </para> + + <screen> + % <userinput>scons -Q --tree=derived</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + cc -o prog f1.o f2.o f3.o + +-. + </screen> + + <para> + + You can use the <literal>status</literal> + modifier with <literal>derived</literal> as well: + + </para> + + <screen> + % <userinput>scons -Q --tree=derived,status</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + cc -o prog f1.o f2.o f3.o + E = exists + R = exists in repository only + b = implicit builder + B = explicit builder + S = side effect + P = precious + A = always build + C = current + N = no clean + H = no cache + + [E b ]+-. + [E B C ] +-f1.o + [E B C ] +-f2.o + [E B C ] +-f3.o + [E B C ] +-prog + [E B C ] +-f1.o + [E B C ] +-f2.o + [E B C ] +-f3.o + </screen> + + <para> + + Note that the order of the <literal>--tree=</literal> + arguments doesn't matter; + <literal>--tree=status,derived</literal> is + completely equivalent. + + </para> + + <para> + + The default behavior of the <literal>--tree</literal> option + is to repeat all of the dependencies each time the library dependency + (or any other dependency file) is encountered in the tree. + If certain target files share other target files, + such as two programs that use the same library: + + </para> + + <programlisting> + env = Environment(CPPPATH = ['.'], + LIBS = ['foo'], + LIBPATH = ['.']) + env.Library('foo', ['f1.c', 'f2.c', 'f3.c']) + env.Program('prog1.c') + env.Program('prog2.c') + </programlisting> + + <para> + + Then there can be a <emphasis>lot</emphasis> of repetition in the + <literal>--tree=</literal> output: + + </para> + + <screen> + % <userinput>scons -Q --tree=all</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + ar rc libfoo.a f1.o f2.o f3.o + ranlib libfoo.a + cc -o prog1.o -c -I. prog1.c + cc -o prog1 prog1.o -L. -lfoo + cc -o prog2.o -c -I. prog2.c + cc -o prog2 prog2.o -L. -lfoo + +-. + +-- + +-SConstruct + +-f1.c + +-f1.o + | +-f1.c + | +-inc.h + +-f2.c + +-f2.o + | +-f2.c + | +-inc.h + +-f3.c + +-f3.o + | +-f3.c + | +-inc.h + +-inc.h + +-libfoo.a + | +-f1.o + | | +-f1.c + | | +-inc.h + | +-f2.o + | | +-f2.c + | | +-inc.h + | +-f3.o + | +-f3.c + | +-inc.h + +-prog1 + | +-prog1.o + | | +-prog1.c + | | +-inc.h + | +-libfoo.a + | +-f1.o + | | +-f1.c + | | +-inc.h + | +-f2.o + | | +-f2.c + | | +-inc.h + | +-f3.o + | +-f3.c + | +-inc.h + +-prog1.c + +-prog1.o + | +-prog1.c + | +-inc.h + +-prog2 + | +-prog2.o + | | +-prog2.c + | | +-inc.h + | +-libfoo.a + | +-f1.o + | | +-f1.c + | | +-inc.h + | +-f2.o + | | +-f2.c + | | +-inc.h + | +-f3.o + | +-f3.c + | +-inc.h + +-prog2.c + +-prog2.o + +-prog2.c + +-inc.h + </screen> + + <para> + + In a large configuration with many internal libraries + and include files, + this can very quickly lead to huge output trees. + To help make this more manageable, + a <literal>prune</literal> modifier may + be added to the option list, + in which case &SCons; + will print the name of a target that has + already been visited during the tree-printing + in <literal>[square brackets]</literal> + as an indication that the dependencies + of the target file may be found + by looking farther up the tree: + + </para> + + <screen> + % <userinput>scons -Q --tree=prune</userinput> + cc -o f1.o -c -I. f1.c + cc -o f2.o -c -I. f2.c + cc -o f3.o -c -I. f3.c + ar rc libfoo.a f1.o f2.o f3.o + ranlib libfoo.a + cc -o prog1.o -c -I. prog1.c + cc -o prog1 prog1.o -L. -lfoo + cc -o prog2.o -c -I. prog2.c + cc -o prog2 prog2.o -L. -lfoo + +-. + +-- + +-SConstruct + +-f1.c + +-f1.o + | +-f1.c + | +-inc.h + +-f2.c + +-f2.o + | +-f2.c + | +-inc.h + +-f3.c + +-f3.o + | +-f3.c + | +-inc.h + +-inc.h + +-libfoo.a + | +-[f1.o] + | +-[f2.o] + | +-[f3.o] + +-prog1 + | +-prog1.o + | | +-prog1.c + | | +-inc.h + | +-[libfoo.a] + +-prog1.c + +-[prog1.o] + +-prog2 + | +-prog2.o + | | +-prog2.c + | | +-inc.h + | +-[libfoo.a] + +-prog2.c + +-[prog2.o] + </screen> + + <para> + + Like the <literal>status</literal> keyword, + the <literal>prune</literal> argument by itself + is equivalent to <literal>--tree=all,prune</literal>. + + </para> + + </section> + + <section> + + <title>How is &SCons; Constructing the Command Lines It Executes? the &debug-presub; Option</title> + + <para> + + Sometimes it's useful to look at the + pre-substitution string + that &SCons; uses to generate + the command lines it executes. + This can be done with the &debug-presub; option: + + </para> + + + + <!-- + + Have to capture output here, otherwise the - -debug=presub output + shows the Python functions from the sconsdoc.py execution wrapper + used to generate this manual, not the underlying command-line strings. + + <scons_output example="presub"> + <scons_output_command>scons -Q - -debug=presub</scons_output_command> + </scons_output> + + --> + + <screen> + % <userinput>scons -Q --debug=presub</userinput> + Building prog.o with action: + $CC -o $TARGET -c $CFLAGS $CCFLAGS $_CCOMCOM $SOURCES + cc -o prog.o -c -I. prog.c + Building prog with action: + $SMART_LINKCOM + cc -o prog prog.o + </screen> + + </section> + + <section> + + <title>Where is &SCons; Searching for Libraries? the &debug-findlibs; Option</title> + + <para> + + To get some insight into what library names + &SCons; is searching for, + and in which directories it is searching, + Use the <literal>--debug=findlibs</literal> option. + Given the following input &SConstruct; file: + + </para> + + <programlisting> + env = Environment(LIBPATH = ['libs1', 'libs2']) + env.Program('prog.c', LIBS=['foo', 'bar']) + </programlisting> + + <para> + + And the libraries <filename>libfoo.a</filename> + and <filename>libbar.a</filename> + in <filename>libs1</filename> and <filename>libs2</filename>, + respectively, + use of the <literal>--debug=findlibs</literal> option yields: + + </para> + + <screen> + % <userinput>scons -Q --debug=findlibs</userinput> + findlibs: looking for 'libfoo.a' in 'libs1' ... + findlibs: ... FOUND 'libfoo.a' in 'libs1' + findlibs: looking for 'libfoo.so' in 'libs1' ... + findlibs: looking for 'libfoo.so' in 'libs2' ... + findlibs: looking for 'libbar.a' in 'libs1' ... + findlibs: looking for 'libbar.a' in 'libs2' ... + findlibs: ... FOUND 'libbar.a' in 'libs2' + findlibs: looking for 'libbar.so' in 'libs1' ... + findlibs: looking for 'libbar.so' in 'libs2' ... + cc -o prog.o -c prog.c + cc -o prog prog.o -Llibs1 -Llibs2 -lfoo -lbar + </screen> + + </section> + + <!-- + + <section> + + <title>What Implicit Dependencies Did the &SCons; Scanner find? the &debug-includes; Option</title> + + <para> + + XXX explain the - - debug=includes option + + </para> + + <scons_example name="includes"> + <file name="SConstruct" printme="1"> + env = Environment(CPPPATH = ['inc1', 'inc2']) + env.Program('prog.c') + </file> + <file name="prog.c"> + #include "file1.h" + #include "file2.h" + prog.c + </file> + <file name="inc1/file1.h"> + inc1/file1.h + </file> + <file name="inc2/file2.h"> + inc2/file2.h + </file> + </scons_example> + + <scons_output example="includes"> + <scons_output_command>scons -Q - - debug=includes prog</scons_output_command> + </scons_output> + + </section> + + --> + + <section> + + <title>Where is &SCons; Blowing Up? the &debug-stacktrace; Option</title> + + <para> + + In general, &SCons; tries to keep its error + messages short and informative. + That means we usually try to avoid showing + the stack traces that are familiar + to experienced Python programmers, + since they usually contain much more + information than is useful to most people. + + </para> + + <para> + + For example, the following &SConstruct; file: + + </para> + + <programlisting> + Program('prog.c') + </programlisting> + + <para> + + Generates the following error if the + <filename>prog.c</filename> file + does not exist: + + </para> + + <screen> + % <userinput>scons -Q</userinput> + scons: *** Source `prog.c' not found, needed by target `prog.o'. Stop. + </screen> + + <para> + + In this case, + the error is pretty obvious. + But if it weren't, + and you wanted to try to get more information + about the error, + the &debug-stacktrace; option + would show you exactly where in the &SCons; source code + the problem occurs: + + </para> + + <screen> + % <userinput>scons -Q --debug=stacktrace</userinput> + scons: *** Source `prog.c' not found, needed by target `prog.o'. Stop. + scons: internal stack trace: + File "bootstrap/src/engine/SCons/Job.py", line 114, in start + File "bootstrap/src/engine/SCons/Taskmaster.py", line 169, in prepare + File "bootstrap/src/engine/SCons/Node/FS.py", line 2220, in prepare + File "bootstrap/src/engine/SCons/Node/__init__.py", line 819, in prepare + </screen> + + <para> + + Of course, if you do need to dive into the &SCons; source code, + we'd like to know if, or how, + the error messages or troubleshooting options + could have been improved to avoid that. + Not everyone has the necessary time or + Python skill to dive into the source code, + and we'd like to improve &SCons; + for those people as well... + + </para> + + </section> + + <section> + + <title>How is &SCons; Making Its Decisions? the &taskmastertrace; Option</title> + + <para> + + The internal &SCons; subsystem that handles walking + the dependency graph + and controls the decision-making about what to rebuild + is the <literal>Taskmaster</literal>. + &SCons; supports a <literal>--taskmastertrace</literal> + option that tells the Taskmaster to print + information about the children (dependencies) + of the various Nodes on its walk down the graph, + which specific dependent Nodes are being evaluated, + and in what order. + + </para> + + <para> + + The <literal>--taskmastertrace</literal> option + takes as an argument the name of a file in + which to put the trace output, + with <filename>-</filename> (a single hyphen) + indicating that the trace messages + should be printed to the standard output: + + </para> + + <programlisting> + env = Environment(CPPPATH = ['.']) + env.Program('prog.c') + </programlisting> + + <screen> + % <userinput>scons -Q --taskmastertrace=- prog</userinput> + Taskmaster: 'prog': children: + ['prog.o'] + waiting on unstarted children: + ['prog.o'] + Taskmaster: 'prog.o': children: + ['inc.h', 'prog.c'] + evaluating prog.o + cc -o prog.o -c -I. prog.c + Taskmaster: 'prog': children: + ['prog.o'] + evaluating prog + cc -o prog prog.o + Taskmaster: 'prog': already handled (executed) + </screen> + + <para> + + The <literal>--taskmastertrace</literal> option + doesn't provide information about the actual + calculations involved in deciding if a file is up-to-date, + but it does show all of the dependencies + it knows about for each Node, + and the order in which those dependencies are evaluated. + This can be useful as an alternate way to determine + whether or not your &SCons; configuration, + or the implicit dependency scan, + has actually identified all the correct dependencies + you want it to. + + </para> + + </section> + + <!-- + + <section> + + <title>Where Are My Build Bottlenecks? the &profile; Option</title> + + <para> + + XXX explain the - - profile= option + + </para> + + </section> + + --> + + <!-- + + <section> + <title>Troubleshooting Shared Caching: the &cache-debug; Option</title> + + <para> + + XXX describe the - - cache-debug option + XXX maybe point to the caching.in chapter? + + </para> + + </section> + + --> |