path: root/doc
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authorBoris Kolpackov <boris@codesynthesis.com>2021-04-21 09:09:18 +0200
committerBoris Kolpackov <boris@codesynthesis.com>2021-04-22 09:02:03 +0200
commit35c1c44bc5f75a327f5d879373a9683af2072a1a (patch)
treeac61394ad33284a0d772d4c62f90456c05e82eac /doc
parent09c231965f9f8e8f1e86f127a22f112d63ef4d9b (diff)
Document use of depdb-env for manually tracking changes to environment
Diffstat (limited to 'doc')
1 files changed, 18 insertions, 0 deletions
diff --git a/doc/manual.cli b/doc/manual.cli
index af9699e..3ee3016 100644
--- a/doc/manual.cli
+++ b/doc/manual.cli
@@ -5741,6 +5741,24 @@ if ($foo != [null])
cxx.poptions += \"-DUSE_FOO=$foo\"
+Additionally, if invoking a program in an ad hoc recipe that either does not
+provide the metadata or does not report the environment as part of it, then we
+additionally should track the changes to the relevant environment variables
+manually using the \c{depdb env} builtin. For example:
+import! foo = foo%exe{foo} # Uses FOO and BAR environment variables.
+config.environment FOO BAR
+file{output}: file{input} $foo
+ diag foo $>
+ depdb env FOO BAR
+ $foo $path($<[0]) >$path($>)
\N|Normally, we would want to report variables that affect the build result
rather than build byproducts (for example, diagnostics). This is, for example,
the reason why locale-related environment variables are not saved by default.