skill-linking-check

name	skill-linking-check
description	Reference for checking documentation link integrity after code changes. Covers link target generation, anchor rules, search patterns, and cross-module dependencies.
metadata	{"version":"1.3.0"}

Documentation Link Integrity Reference

Reference material for verifying that code changes don't break documentation links.

When to Use This Skill

This skill activates when:

• Analyzing commits for documentation impact
• Checking if renames break existing links
• Verifying cross-module link integrity
• Predicting QDoc "Can't link to" warnings

What Generates Link Targets

Source	Link Target	Link Syntax
\class ClassName	ClassName	\l{ClassName}
\qmltype TypeName	TypeName	\l{TypeName}, \l [QML]{TypeName}
\fn void Class::method()	Class::method()	\l{Class::method()}
\qmlmethod Type::method()	Type::method()	\l{Type::method()}
\qmlproperty type Type::prop	Type::prop	\l{Type::prop}
\qmlsignal Type::signalName	Type::signalName	\l{Type::signalName}
\enum Class::EnumName	Class::EnumName	\l{Class::EnumName}
\typedef Class::TypeName	Class::TypeName	\l{Class::TypeName}
\property Class::propName	Class::propName	\l{Class::propName}
\title Page Title	Page Title	\l{Page Title}
\section1 Section Name	#section-name	\l{Type#Section Name}
\target custom-anchor	#custom-anchor	\l{#custom-anchor}
\keyword Search Term	Search Term	\l{Search Term}
\externalpage URL	External title	\l{External Title}
QML_NAMED_ELEMENT(X)	QML type X	\l{X}, \l [QML]{X}
QML_ELEMENT	QML type (class name)	\l{ClassName}

QML Registration Macros

These C++ macros control what QML type names are exposed:

Macro	Effect	Documentation Impact
QML_NAMED_ELEMENT(Name)	Exposes as Name in QML	Links use Name, not C++ class name
QML_ELEMENT	Exposes using C++ class name	Links use class name
QML_ANONYMOUS	No QML name	Cannot link to type
QML_UNCREATABLE(reason)	Type exists but not creatable	Can still link
QML_SINGLETON	Singleton type	Can link normally

Key insight: When QML_NAMED_ELEMENT changes, ALL documentation links to the old name break.

Anchor Generation Rules

QDoc converts section titles to anchors:

1. Lowercase all characters
2. Replace spaces with hyphens
3. Remove special characters
4. Collapse multiple hyphens

Section Title	Generated Anchor
Basic Usage	#basic-usage
C++ Integration	#c-integration
QML/Qt Quick	#qml-qt-quick
Hosting in Qt GUI	#hosting-in-qt-gui
Step 1: Setup	#step-1-setup
FAQ & Troubleshooting	#faq-troubleshooting

Link Syntax Quick Reference

Target Type	Correct Syntax	Common Mistake
Class	\l{QWidget}	\l{qwidget.html}
QML type	\l{Rectangle}	\l{QQuickRectangle}
QML type (explicit)	\l [QML]{Item}	\l{Item} (ambiguous)
Member	\l{QWidget::show()}	\l{show()}
QML property	\l{Item::width}	\l{Item.width}
Section in type	\l{QWidget#Public Functions}	\l{qwidget.html#public-functions}
Page by title	\l{Getting Started}	\l{getting-started.html}
Custom target	\l{#custom-anchor}	Works if \target custom-anchor exists

Search Patterns for References

QDoc Link Commands

Note: \l and \sa use the same link resolution mechanism (findNodeForAtom()). Both commands will break if a target is renamed or removed.

# \l links to a name
grep -rn "\\\\l.*{.*TargetName" --include="*.qdoc" --include="*.cpp" qt*/

# \l with QML genus
grep -rn "\\\\l \[QML\].*{.*TargetName" --include="*.qdoc" qt*/

# \l with display text
grep -rn "\\\\l.*{.*TargetName.*}" --include="*.qdoc" qt*/

\sa (See Also) References

See also: skill-qdoc/references/link-resolution.md for comprehensive \sa syntax, parsing details, and resolution behavior.

\sa creates comma-separated link lists in "See also" sections. Search for these separately because the syntax differs from \l.

# Basic \sa search (target anywhere in line)
grep -rn "\\\\sa.*TargetName" --include="*.qdoc" --include="*.cpp" qt*/

# \sa with braced target (for targets with spaces)
grep -rn "\\\\sa.*{.*TargetName" --include="*.qdoc" --include="*.cpp" qt*/

# \sa at start of target list
grep -rn "\\\\sa TargetName" --include="*.qdoc" --include="*.cpp" qt*/

# \sa with target in middle of list (after comma)
grep -rn "\\\\sa.*, *TargetName" --include="*.qdoc" --include="*.cpp" qt*/

\sa syntax variations to search for:

Pattern	Matches
\sa TargetName	First item, no braces
\sa {TargetName}	First item, with braces
\sa OtherThing, TargetName	After comma
\sa {Other Thing}, {TargetName}	Braced after comma
\sa {Class::}{TargetName()}	C++ member shorthand

QDoc Topic Commands

# \class documentation
grep -rn "\\\\class.*ClassName" --include="*.cpp" --include="*.qdoc" qt*/

# \qmltype documentation
grep -rn "\\\\qmltype.*TypeName" --include="*.cpp" --include="*.qdoc" qt*/

# \fn documentation
grep -rn "\\\\fn.*functionName" --include="*.cpp" qt*/

Code References

# QML_NAMED_ELEMENT usage
grep -rn "QML_NAMED_ELEMENT(.*TypeName" --include="*.h" qt*/

# Include/snippet paths
grep -rn "\\\\snippet.*filename" --include="*.qdoc" --include="*.cpp" qt*/
grep -rn "\\\\include.*filename" --include="*.qdoc" qt*/

Index File Searches

# Local index files
grep 'name="TargetName"' */doc/*/*.index

# Check if target is internal
grep -A2 'name="TargetName"' */doc/*/*.index | grep 'status="internal"'

# Get href for Output field
grep 'name="TargetName"' */doc/*/*.index | grep -o 'href="[^"]*"'

Online Index Files

Available at https://doc-snapshots.qt.io/qt6-dev/{module}.index:

Module	Index URL
QtCore	qtcore.index
QtGui	qtgui.index
QtWidgets	qtwidgets.index
QtQml	qtqml.index
QtQuick	qtquick.index
QtQuickControls	qtquickcontrols.index

Change Types and Impact

Breaking Changes (Will Cause Warnings)

Change	Impact	Search Pattern
QML_NAMED_ELEMENT(Old) → QML_NAMED_ELEMENT(New)	All \l{Old} links break	grep "\\\\l.*{.*Old"
Class renamed	\l{OldClass}, \class OldClass break	grep "OldClass"
Function removed	\l{Class::func()} breaks	grep "\\\\l.*func"
\target X removed	\l{#X} breaks	grep "#X"
\title X changed (different words)	\l{X} breaks	grep "\\\\l.*{.*X"
\externalpage title changed	\l{Old Title} breaks	grep "\\\\l.*{.*Old Title"
File renamed	\snippet, \include break	grep "oldfile"

Cosmetic Changes (Links Survive)

Change	Why Safe	Action
\title X case-only change	QDoc normalizes targets to lowercase	Update refs for consistency
\target X case-only change	Same normalization	Update refs for consistency

Non-Breaking Changes (Safe)

Change	Why Safe
New class/type added	No existing links to break
New function added	No existing links to break
Implementation changed	Documentation unaffected
Private API changed	Not documented (or \internal)

Potentially Breaking (Check Carefully)

Change	Risk	Check
Enum value renamed	Medium	Search for \value OldValue
Parameter renamed	Low	Only affects \a param in same file
Namespace changed	High	Search for fully qualified names
Module renamed	Very High	All cross-module links break

Report Template

## Link Integrity Check

**Change:** {describe what was renamed/removed/changed}

**Searches Performed:**
- [ ] `\l{}` patterns in *.qdoc, *.cpp
- [ ] `\sa` references
- [ ] Index file search (local)
- [ ] Index file search (online)
- [ ] Cross-module dependency check

**Findings:**

| Location | Reference | Status |
|----------|-----------|--------|
| `file.qdoc:22` | `\l{OldName}` | BROKEN |
| `other.qdoc:45` | `\sa OldName` | BROKEN |

**Result:** {N issues found / No issues}

**Required Updates:**
1. `file.qdoc:22` - Change `\l{OldName}` to `\l{NewName}`
2. `other.qdoc:45` - Change `\sa OldName` to `\sa NewName`

Special Cases

New Content

If the change ADDS a new class/type/page (not modifying existing):

• No existing links can be broken
• Report: "New content - no existing links possible"

Internal APIs

If the changed item is marked \internal:

• External documentation should not link to it
• If links exist, they're already bugs
• Report: "Internal API - external links would already be broken"

Deprecated APIs

If the changed item is marked \deprecated:

• Links may exist but content is being phased out
• Lower priority to fix
• Report: "Deprecated API - consider removing references"

Case Sensitivity

QDoc normalizes all target keys to lowercase ASCII via asAsciiPrintable() (utilities.cpp:157-197). This means:

• \l{Foo}, \l{foo}, and \l{FOO} all resolve to the same target
• \l{Supported Platforms} resolves identically to \l{Supported platforms}
• Section anchors: Also case-insensitive (same normalization)
• QML types: Also case-insensitive for resolution (but conventionally PascalCase)

Impact on renames: A case-only title rename (e.g., \title Supported Platforms to \title Supported platforms) does NOT break links. However, references should still be updated for consistency — categorize as Cosmetic, not Breaking.

What IS case-sensitive: The \l display text (the part the reader sees) is rendered as-is. Only the link target lookup is normalized.

Silent Misdirection (No Warning)

When a \title or \class is renamed but another module retains a \target or \keyword with the same normalized name, QDoc resolves orphaned links to that surviving definition. This produces no warning — the link appears to work but points to the wrong page.

QDoc's ambiguity detection (tree.cpp:1059-1090) only checks for duplicate page titles within the same tree. Cross-module conflicts are not detected. The findUnambiguousTarget() function returns the first/best match by priority without warning about cross-module duplicates.

Detection: After identifying a rename, search all index files and source for any other definition of the old name:

grep 'title="OldName"' */doc/*/*.index
grep -rn "\\\\target.*OldName" --include="*.qdoc" qt*/
grep -rn "\\\\keyword.*OldName" --include="*.qdoc" qt*/

Severity: Always Breaking, even though QDoc produces no warning. Silent misdirection is harder to detect than a broken link.

Keyword and Target Aliases

\keyword, \target, and \title all create link targets that participate in the same resolution. QDoc assigns priorities (tree.cpp):

Source	Priority	Wins When
\keyword	1 (highest)	Always wins over target/section
\target	2	Wins over section titles
Section title (\section1)	3 (lowest)	Only if no keyword/target

When multiple definitions with the same normalized name exist:

• Same module: findUnambiguousTarget() picks the lowest priority number
• Cross-module: First match found wins — behavior is unpredictable and depends on index file load order

Impact on renames:

Scenario	Effect
Page has \keyword OldTitle after title rename	Old links still resolve — backward-compatible
Another module has \target OldTitle	Orphaned links resolve to wrong page — silent misdirection
Two modules define same \keyword	QDoc picks based on load order — ambiguous

Search for aliases:

# Existing aliases for old name (mitigations)
grep -rn "\\\\keyword.*OldName" --include="*.qdoc" qt*/
grep -rn "\\\\target.*OldName" --include="*.qdoc" qt*/

# Existing definitions for new name (conflicts)
grep -rn "\\\\keyword.*NewName" --include="*.qdoc" qt*/
grep -rn "\\\\target.*NewName" --include="*.qdoc" qt*/

# Index file check (catches cross-module aliases)
grep 'title="OldName"' */doc/*/*.index

External Pages

\externalpage creates an ExternalPageNode (inherits PageNode) that participates in normal link resolution. You can link to external pages with \l{Title} just like regular pages.

External page definitions are often collected in a single file (e.g., external-resources.qdoc). A title change there breaks every \l{Title} that references it across all modules.

# Search for references to an external page title
grep -rn "\\\\l.*{.*Old External Title" --include="*.qdoc" qt*/

# Find all \externalpage definitions
grep -rn "\\\\externalpage" --include="*.qdoc" qt*/

Cross-Module Dependencies

Qt modules declare dependencies in qdocconf:

depends = QtCore QtGui QtWidgets

When module A declares depends = B C, QDoc loads B.index and C.index into shared target maps (qdocdatabase.cpp:1316-1327). All targets from B and C become resolvable from A's documentation via \l.

Dependency Direction

Direction	Risk	Detection
Downstream (Y depends on X)	Y's \l{OldName} breaks if X renames	Grep Y's sources for old name
Upstream (X depends on Z)	Z's \target OldName silently captures orphaned links from X	Grep Z's index for old name

Upstream conflicts are more dangerous because they produce no QDoc warning — see "Silent Misdirection" above. Always check both directions for renames.

# Downstream: find modules that depend on the changed module
grep -rl "depends.*ChangedModule" qt*/src/*/doc/*.qdocconf

# Upstream: find what the changed module depends on
grep "depends" {changed-module}/src/*/doc/*.qdocconf

# For each dependency, check if it defines the old name
grep 'title="OldName"' */doc/{dependency}/{dependency}.index

Common Dependency Chains

qtbase (QtCore, QtGui, QtWidgets)
    ↓
qtdeclarative (QtQml, QtQuick)
    ↓
qtquickcontrols
    ↓
qtdoc (links to everything)

High-Impact Modules

Module	Risk	Reason
qtbase	High	Foundation, many dependents
qtdeclarative	High	QML types widely referenced
qtdoc	Medium	Overview docs, cross-links

Integration

• skill-qdoc: Link resolution details, node system
• skill-doc-diff: Output format for fixes
• skill-all-docs: Module and repository information

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Version History

• v1.3 (2026-04-10): QDoc source-verified resolution behavior

  • Fixed case sensitivity: QDoc normalizes targets to lowercase (utilities.cpp:157-197). Case-only renames are Cosmetic, not Breaking.
  • Added "Silent Misdirection" section: cross-module target conflicts produce no QDoc warning (tree.cpp ambiguity check is same-tree only)
  • Added "Keyword and Target Aliases" section: priority system (keyword=1, target=2, section=3) and conflict detection
  • Added "External Pages" section: \externalpage creates linkable PageNode, title changes break \l{Title} references
  • Rewrote "Cross-Module Dependencies" with dependency direction (downstream vs upstream) and conflict detection searches
  • Added "Cosmetic Changes" table for case-only renames

• v1.2 (2026-03-12): Added cross-references to reduce duplication

  • Added reference to skill-qdoc/references/link-resolution.md for \sa details

• v1.1 (2026-03-12): Enhanced \sa documentation

  • Added note that \l and \sa use same resolution mechanism
  • Expanded \sa search patterns section with syntax variations
  • Added table of \sa syntax patterns to search for

• v1.0 (initial): Link integrity reference with search patterns