diff options
Diffstat (limited to 'doc/manual.cli')
| -rw-r--r-- | doc/manual.cli | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/doc/manual.cli b/doc/manual.cli index b72700d..ab832fe 100644 --- a/doc/manual.cli +++ b/doc/manual.cli @@ -1418,7 +1418,7 @@ if ($cc.class == 'gcc') } if ($c.target.class != 'windows') - c.libs += -lpthread # only C + c.libs += -ldl # only C \ Additionally, as we will see in \l{#intro-operations-config Configuring}, @@ -4443,12 +4443,12 @@ Instead of printing the entire scope, we can also print individual targets by specifying one or more target names in \c{dump}. To make things more interesting, let's convert our \c{hello} project to use a utility library, similar to the unit testing setup (\l{#intro-unit-test Implementing Unit -Testing}). We will also link to the \c{pthread} library to see an example of a +Testing}). We will also link to the \c{dl} library to see an example of a target-specific variable being dumped: \ exe{hello}: libue{hello}: bin.whole = false -exe{hello}: cxx.libs += -lpthread +exe{hello}: cxx.libs += -ldl libue{hello}: {hxx cxx}{**} dump exe{hello} @@ -4460,7 +4460,7 @@ The output will look along these lines: buildfile:5:1: dump: /tmp/hello/hello/exe{hello.?}: { - [strings] cxx.libs = -lpthread + [strings] cxx.libs = -ldl } /tmp/hello/hello/exe{hello.?}: /tmp/hello/hello/:libue{hello.?}: { @@ -4561,6 +4561,25 @@ Higher verbosity levels result in more and more tracing statements being printed. These include \c{buildfile} loading and parsing, prerequisite to target resolution, as well as build system module and rule-specific logic. +While the tracing statements can be helpful in understanding what is +happening, they don't make it easy to see why things are happening a +certain way. In particular, one question that is often encountered during +build troubleshooting is which dependency chain causes matching or execution +of a particular target. These questions can be answered with the help of +the \c{--trace-match} and \c{--trace-execute} options. For example, if we +want to understand what causes the update of \c{obje{hello\}} in the +\c{hello} project above: + +\ +$ b -s --trace-execute 'obje{hello}' +info: updating hello/obje{hello} + info: using rule cxx.compile + info: while updating hello/libue{hello} + info: while updating hello/exe{hello} + info: while updating dir{hello/} + info: while updating dir{./} +\ + Another useful diagnostics option is \c{--mtime-check}. When specified, the build system performs a number of file modification time sanity checks that can be helpful in diagnosing spurious rebuilds. |