qdoc: Don't warn about undocumented namespaces if -no-link-errors is set

The documentation for the namespace can be (and often is) located in
another module. As -no-link-errors is set when testing documentation
builds of individual module without loading the .index files of any
dependencies, skip these warnings.

Document the warning.

Fixes: QTBUG-97453
Change-Id: Ie899f29fde20082a5880a6c9d475db1a88b70085
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
(cherry picked from commit f701a03e1f2362b020b7a962187a0fe73632f17f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 24 insertions, 7 deletions

diff --git a/src/qdoc/doc/qdoc-manual-qdocconf.qdoc b/src/qdoc/doc/qdoc-manual-qdocconf.qdoc
index c47d49784..3cdec870e 100644
--- a/src/qdoc/doc/qdoc-manual-qdocconf.qdoc
+++ b/src/qdoc/doc/qdoc-manual-qdocconf.qdoc
@@ -344,7 +344,7 @@
     of dependencies for a single module consists of actual build
     dependencies. In addition, if there is a documentation project
     (module) that acts as a top-level entry point for the entire
-    documentation set and provides \l {navigation-variable}[navigation}
+    documentation set and provides \l {navigation-variable}{navigation}
     links, each module documentation should include it as a dependency.
 
     When QDoc generates documentation for a project, it will also generate
@@ -1902,8 +1902,7 @@
     \target indexes-variable
     \section1 indexes
 
-    The \l {indexes-variable}[indexes} variable defines a set of paths
-    to index files to load.
+    The \c indexes variable defines a set of paths to index files to load.
 
     \badcode
     indexes = \
diff --git a/src/qdoc/doc/qdoc-warnings.qdoc b/src/qdoc/doc/qdoc-warnings.qdoc
index cfaf86059..d40ad6abd 100644
--- a/src/qdoc/doc/qdoc-warnings.qdoc
+++ b/src/qdoc/doc/qdoc-warnings.qdoc
@@ -152,6 +152,18 @@
     containing \l {namespace-command}{\\namespace} commands with the same
     argument, <name>.
 
+    \section1 <name> is documented, but namespace <namespace> is not documented in any module
+
+    The documentation for \e {<name>} was found, but \e{<name>} is declared
+    under a namespace that is either undocumented or QDoc was unable to
+    locate the documentation for it.
+
+    This can be resolved by either documenting \e{<namespace>}, or if it is
+    already documented in another module, ensure that this module has
+    a dependency to it.
+
+    See also \l {depends-variable}{depends} and {indexes-variable}{indexes}.
+
     \section1 Clang couldn't find function when parsing \\fn <signature>
 
     When parsing a \l {fn-command}{\\fn} statement, Clang compares this with the
diff --git a/src/qdoc/qdocdatabase.cpp b/src/qdoc/qdocdatabase.cpp
index 305003f82..3d3bc20ba 100644
--- a/src/qdoc/qdocdatabase.cpp
+++ b/src/qdoc/qdocdatabase.cpp
@@ -1090,6 +1090,8 @@ void QDocDatabase::resolveNamespaces()
 {
     if (!m_namespaceIndex.isEmpty())
         return;
+
+    bool linkErrors = !Config::instance().getBool(CONFIG_NOLINKERRORS);
     NodeMultiMap namespaceMultimap;
     Tree *t = m_forest.firstTree();
     while (t) {
@@ -1122,10 +1124,14 @@ void QDocDatabase::resolveNamespaces()
                     }
                 }
             } else if (!indexNamespace) {
-                // warn about documented children in undocumented namespaces
-                for (auto *node : namespaces) {
-                    if (!node->isIndexNode())
-                        static_cast<NamespaceNode *>(node)->reportDocumentedChildrenInUndocumentedNamespace();
+                // Warn about documented children in undocumented namespaces.
+                // As the namespace can be documented outside this project,
+                // skip the warning if -no-link-errors is set
+                if (linkErrors) {
+                    for (auto *node : namespaces) {
+                        if (!node->isIndexNode())
+                            static_cast<NamespaceNode *>(node)->reportDocumentedChildrenInUndocumentedNamespace();
+                    }
                 }
             } else {
                 for (auto *node : namespaces) {