From 8ad9c0111ccfbac9a06513fa5c9baa6dc4e48970 Mon Sep 17 00:00:00 2001
From: Christian Kandeler <christian.kandeler@qt.io>
Date: Wed, 25 Nov 2020 11:12:30 +0100
Subject: [PATCH] clangbackend: Another workaround for libclang cursor
 weirdness

Sometimes, clang_getCursor() erroneously returns an invalid cursor, in
which case we may be able to retrieve the real one via
clang_annotateTokens(). This is basically the reverse of the issue we
recently had, where we had to call clang_getCursor() to get information
missing from clang_annotateTokens().

Fixes: QTCREATORBUG-21194
Change-Id: Ie8c4767bca03bd1b27e3ef1f906378fc1d436b90
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
---
 .../clangbackend/source/clangfollowsymbol.cpp | 15 +-------------
 .../source/clangtooltipinfocollector.cpp      | 20 +++++++++++++++++--
 src/tools/clangbackend/source/token.cpp       | 13 ++++++++++++
 src/tools/clangbackend/source/token.h         |  4 ++++
 4 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/src/tools/clangbackend/source/clangfollowsymbol.cpp b/src/tools/clangbackend/source/clangfollowsymbol.cpp
index c38d397eeb1..e2c619ef3fc 100644
--- a/src/tools/clangbackend/source/clangfollowsymbol.cpp
+++ b/src/tools/clangbackend/source/clangfollowsymbol.cpp
@@ -71,19 +71,6 @@ static SourceRangeContainer extractMatchingTokenRange(const Cursor &cursor,
     return SourceRangeContainer();
 }
 
-static int getTokenIndex(CXTranslationUnit tu, const Tokens &tokens, uint line, uint column)
-{
-    int tokenIndex = -1;
-    for (int i = tokens.size() - 1; i >= 0; --i) {
-        const SourceRange range(tu, tokens[i].extent());
-        if (range.contains(line, column)) {
-            tokenIndex = i;
-            break;
-        }
-    }
-    return tokenIndex;
-}
-
 FollowSymbolResult FollowSymbol::followSymbol(CXTranslationUnit tu,
                                               const Cursor &fullCursor,
                                               uint line,
@@ -100,7 +87,7 @@ FollowSymbolResult FollowSymbol::followSymbol(CXTranslationUnit tu,
         return SourceRangeContainer();
 
     std::vector<Cursor> cursors = tokens.annotate();
-    int tokenIndex = getTokenIndex(tu, tokens, line, column);
+    const int tokenIndex = tokens.getTokenIndex(tu, line, column);
     QTC_ASSERT(tokenIndex >= 0, return SourceRangeContainer());
 
     const Utf8String tokenSpelling = tokens[tokenIndex].spelling();
diff --git a/src/tools/clangbackend/source/clangtooltipinfocollector.cpp b/src/tools/clangbackend/source/clangtooltipinfocollector.cpp
index af28c7a5a9f..06bc98203b7 100644
--- a/src/tools/clangbackend/source/clangtooltipinfocollector.cpp
+++ b/src/tools/clangbackend/source/clangtooltipinfocollector.cpp
@@ -512,9 +512,25 @@ Utf8String ToolTipInfoCollector::lineRange(const Utf8String &filePath,
 
 ToolTipInfo ToolTipInfoCollector::collect(uint line, uint column) const
 {
-    const Cursor cursor = clang_getCursor(m_cxTranslationUnit, toCXSourceLocation(line, column));
+    Cursor cursor = clang_getCursor(m_cxTranslationUnit, toCXSourceLocation(line, column));
+    if (!cursor.isValid()) { // QTCREATORBUG-21194
+        Tokens tokens(Cursor(clang_getTranslationUnitCursor(m_cxTranslationUnit)).sourceRange());
+        if (!tokens.size())
+            return {};
+
+        // TODO: Only annotate the tokens up until the location we are interested in?
+        //       Same goes for FollowSymbol.
+        const std::vector<Cursor> cursors = tokens.annotate();
+
+        const int tokenIndex = tokens.getTokenIndex(m_cxTranslationUnit, line, column);
+        QTC_ASSERT(tokenIndex >= 0, return {});
+        const Utf8String tokenSpelling = tokens[tokenIndex].spelling();
+        if (tokenSpelling.isEmpty())
+            return {};
+        cursor = cursors[tokenIndex];
+    }
     if (!cursor.isValid())
-        return ToolTipInfo(); // E.g. cursor on ifdeffed out range
+        return {};
 
     const Cursor referenced = referencedCursor(cursor);
     QTC_CHECK(referenced.isValid());
diff --git a/src/tools/clangbackend/source/token.cpp b/src/tools/clangbackend/source/token.cpp
index 1bc773e9d98..5fa31528ecc 100644
--- a/src/tools/clangbackend/source/token.cpp
+++ b/src/tools/clangbackend/source/token.cpp
@@ -202,6 +202,19 @@ std::vector<Token>::iterator Tokens::end()
     return m_tokens.end();
 }
 
+int Tokens::getTokenIndex(CXTranslationUnit tu, uint line, uint column) const
+{
+    int tokenIndex = -1;
+    for (int i = size() - 1; i >= 0; --i) {
+        const SourceRange range(tu, (*this)[i].extent());
+        if (range.contains(line, column)) {
+            tokenIndex = i;
+            break;
+        }
+    }
+    return tokenIndex;
+}
+
 Tokens::~Tokens()
 {
     if (m_tokens.empty())
diff --git a/src/tools/clangbackend/source/token.h b/src/tools/clangbackend/source/token.h
index ecfb42f6f45..46635c40019 100644
--- a/src/tools/clangbackend/source/token.h
+++ b/src/tools/clangbackend/source/token.h
@@ -25,6 +25,8 @@
 
 #pragma once
 
+#include <utils/smallstringfwd.h>
+
 #include <clang-c/Index.h>
 
 #include <vector>
@@ -81,6 +83,8 @@ public:
     std::vector<Token>::iterator begin();
     std::vector<Token>::iterator end();
 
+    int getTokenIndex(CXTranslationUnit tu, uint line, uint column) const;
+
     CXTranslationUnit tu() const { return m_cxTranslationUnit; }
 private:
     CXTranslationUnit m_cxTranslationUnit;