[PATCH] D124719: [docs] PCH usage documentation update
Ivan Murashko via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Tue May 3 00:12:57 PDT 2022
ivanmurashko updated this revision to Diff 426588.
ivanmurashko added a comment.
Some clarifications for the direct include example were added
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D124719/new/
https://reviews.llvm.org/D124719
Files:
clang/docs/UsersManual.rst
Index: clang/docs/UsersManual.rst
===================================================================
--- clang/docs/UsersManual.rst
+++ clang/docs/UsersManual.rst
@@ -1219,23 +1219,22 @@
Using a PCH File
^^^^^^^^^^^^^^^^
-A PCH file can then be used as a prefix header when a :option:`-include`
+A PCH file can then be used as a prefix header when a :option:`-include-pch`
option is passed to ``clang``:
.. code-block:: console
- $ clang -include test.h test.c -o test
+ $ clang -include-pch test.h.pch test.c -o test
-The ``clang`` driver will first check if a PCH file for ``test.h`` is
+The ``clang`` driver will check if the PCH file ``test.h.pch`` is
available; if so, the contents of ``test.h`` (and the files it includes)
-will be processed from the PCH file. Otherwise, Clang falls back to
-directly processing the content of ``test.h``. This mirrors the behavior
-of GCC.
+will be processed from the PCH file. Otherwise, Clang will report an error.
.. note::
Clang does *not* automatically use PCH files for headers that are directly
- included within a source file. For example:
+ included within a source file or indirectly via :option:`-include`.
+ For example:
.. code-block:: console
@@ -1246,8 +1245,8 @@
In this example, ``clang`` will not automatically use the PCH file for
``test.h`` since ``test.h`` was included directly in the source file and not
- specified on the command line using :option:`-include`.
-
+ specified on the command line using :option:`-include-pch`.
+
Relocatable PCH Files
^^^^^^^^^^^^^^^^^^^^^
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