Doc: Update info about Clang and clangd preferences

And the Show Preprocessed Source action in the code editor
context menu.

Task-number: QTCREATORBUG-27876
Change-Id: I43ca26d6ee7bb5e0441a37aeb1f7eecbb4ba8fde
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

doc/qtcreator/src/analyze/creator-clang-static-analyzer.qdoc

@@ -132,10 +132,14 @@
             to run in parallel to make the analysis faster on multi-core
             processors.
 
-        \li In the \uicontrol {Diagnostic Configuration} group, select
-            \uicontrol Manage to create or edit a custom configuration.
+        \li The \uicontrol {Diagnostic configuration} field shows the
+            checks to perform. Click the value of the field to open the
+            \uicontrol {Diagnostic Configurations} dialog, where you can
+            select and edit the checks to perform.
 
-        \li Select \uicontrol Copy to create a custom Clang configuration.
+            \image qtcreator-clang-tools-diagnostics-configuration.png "Diagnostics Configuration dialog"
+
+        \li Select \uicontrol Copy to copy the selected diagnostics for editing.
 
             \image qtcreator-clang-copy-diagnostic-configuration.png "Copy Diagnostic Configuration dialog"
 
@@ -148,8 +152,6 @@
             system to the Clang code model for displaying annotations in the
             code editor.
 
-            \image qtcreator-clang-tools-diagnostics-configuration.png "Diagnostics Configuration dialog"
-
         \li In the \uicontrol {Clang-Tidy Checks} tab, select
             \uicontrol {Select Checks} to select the checks to perform.
             To filter the checks, enter a string in the

doc/qtcreator/src/editors/creator-code-syntax.qdoc

@@ -716,4 +716,23 @@
     \uicontrol {Enable auto format on file save}.
 
     \image qtcreator-qml-js-editing.png "QML/JS Editing preferences"
+
+    \if defined(qtcreator)
+    \section1 Inspecting Preprocessed C++ Code
+
+    To analyze the causes of compile errors or errors caused by wrong includes
+    pulled in by dependencies or C++ macros expanding to something unexpected,
+    select \uicontrol {Show Preprocessed Source} in the editor context menu.
+
+    This action expands all C++ macros to their actual code and removes code that
+    is guarded by a currently inactive \c {#ifdef} statements. If you deselect
+    the \uicontrol {Use built-in preprocessor to show pre-processed files} check
+    box in \uicontrol Edit > \uicontrol Preferences > \uicontrol C++ >
+    \uicontrol {Code Model}, this action also expands all
+    \c {"#include <foo.h>"} statements to their actual contents.
+
+    \image qtcreator-clang-code-model-options.png "C++ Code Model preferences"
+
+    \endif
+
 */

doc/qtcreator/src/editors/creator-only/creator-clang-codemodel.qdoc

@@ -114,6 +114,14 @@
         \li To process precompiled headers, deselect the
             \uicontrol {Ignore precompiled headers} check box.
 
+        \li When you select \uicontrol {Show Preprocessed Source} in the code
+            editor context menu, the built-in preprocessor is used to show the
+            pre-processed source file in the editor. To invoke the actual
+            compiler for showing the code, deselect the
+            \uicontrol {Use built-in preprocessor to show pre-processed files}
+            check box. For more information, see
+            \l {Inspecting Preprocessed C++ Code}.
+
         \li To avoid out-of-memory crashes caused by indexing huge source files
             that are typically auto-generated by scripts or code, the size of
             files to index is limited to 5MB by default. To adjust the limit,
@@ -132,6 +140,11 @@
     re-scanning is incremental, so nothing is lost by closing and re-starting
     \QC.
 
+    By default, \QC runs one clangd process per project. If you have created
+    \l{Managing Sessions}{sessions} that contain related projects, you can
+    specify that the projects in the session should be managed by a single
+    clangd process.
+
     The document outline in the \l{Viewing Defined Types and Symbols}
     {Outline} view is backed by clangd's document symbol support, which
     makes the results more reliable than before.
@@ -144,11 +157,11 @@
             \image qtcreator-options-clangd.png "clangd preferences"
         \li In \uicontrol {Path to executable}, enter the path to clangd
             version 14, or later.
-        \li For more accurate results during global symbol searches, select
-            \uicontrol {Enable background indexing}. However, this increases the
-            CPU load the first time you open the project. If clangd background
-            indexing is disabled, \QC falls back to a faster, but less accurate
-            built-in indexer.
+        \li In the \uicontrol {Background indexing} field, select \uicontrol Off
+            to use a faster, but less accurate built-in indexer than the one used
+            by default. You can set the indexing priority depending on whether
+            the accuracy of results or speed is more important to you during
+            global symbol searches.
         \li By default, clangd attempts to use all unused cores. You can set a
             fixed number of cores to use in \uicontrol {Worker thread count}.
             Background indexing also uses this many worker threads.
@@ -164,10 +177,12 @@
         \li Select \uicontrol {Ignore files greater than} to make parsing faster
             by ignoring big files. Specify the maximum size of files to parse in
             the field next to the check box.
-        \li The \uicontrol {Diagnostic Configuration} field shows the Clang
+        \li The \uicontrol {Diagnostic configuration} field shows the Clang
             checks to perform. Click the value of the field to open the
             \uicontrol {Diagnostic Configurations} dialog, where you can
             select and edit the checks to perform.
+        \li Select \uicontrol Add to select sessions that should use a single
+            clangd process for indexing.
     \endlist
 
     \section1 Clang Checks

doc/qtcreator/src/projects/creator-only/creator-projects-settings-code-style.qdoc

@@ -38,9 +38,15 @@
     To specify global code style settings sets for C++ files, select
     \uicontrol Edit > \uicontrol Preferences > \uicontrol C++.
 
+    \image qtcreator-code-style-settings-edit-cpp.png "Edit Code Style Settings dialog"
+
     To specify global code style settings sets for QML files, select
     \uicontrol Edit > \uicontrol Preferences > \uicontrol {Qt Quick}.
 
+    \image qtcreator-code-style-settings-edit-qtquick.png "Edit Code Style Settings view"
+
+    Only \uicontrol General settings are available for QML files.
+
     To configure the editor behavior for the current project:
 
     \list 1
@@ -58,12 +64,6 @@
 
         \li Click \uicontrol Edit to specify code style settings for the project.
 
-            \image qtcreator-code-style-settings-edit-cpp.png "Edit Code Style Settings dialog"
-
-            \note Only \uicontrol General settings are available for QML files.
-
-            \image qtcreator-code-style-settings-edit-qtquick.png "Edit Code Style Settings view"
-
     \endlist
 
     For more information about the settings, see \l{Indenting Text or Code}.