CMakeProjectManager: Fix issues with precompiled headers

Clang code model can break if CMake project uses precompiled headers.

QtCreator will make a copy of the precompiled header, this way it
will not conflict with the build system one.

Ammends 888ea6bbbb0f4c6bb6b5616046e600b9520e4faf

Fixes: QTCREATORBUG-24945
Fixes: QTCREATORBUG-25213
Change-Id: I149fc416cd047683d095758a024de47c7baf681c
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

5 files changed, 81 insertions, 47 deletions

diff --git a/src/libs/utils/fileutils.cpp b/src/libs/utils/fileutils.cpp
index 23be348698..53b8957794 100644
--- a/src/libs/utils/fileutils.cpp
+++ b/src/libs/utils/fileutils.cpp
@@ -220,6 +220,29 @@ bool FileUtils::copyRecursively(const FilePath &srcFilePath, const FilePath &tgt
 }
 
 /*!
+  Copies a file specified by \a srcFilePath to \a tgtFilePath only if \a srcFilePath is different
+  (file size and last modification time).
+
+  Returns whether the operation succeeded.
+*/
+
+bool FileUtils::copyIfDifferent(const FilePath &srcFilePath, const FilePath &tgtFilePath)
+{
+    if (QFile::exists(tgtFilePath.toString())) {
+        const QFileInfo srcFileInfo = srcFilePath.toFileInfo();
+        const QFileInfo tgtFileInfo = tgtFilePath.toFileInfo();
+        if (srcFileInfo.lastModified() == tgtFileInfo.lastModified() &&
+            srcFileInfo.size() == tgtFileInfo.size()) {
+            return true;
+        } else {
+            QFile::remove(tgtFilePath.toString());
+        }
+    }
+
+    return QFile::copy(srcFilePath.toString(), tgtFilePath.toString());
+}
+
+/*!
   If this is a directory, the function will recursively check all files and return
   true if one of them is newer than \a timeStamp. If this is a single file, true will
   be returned if the file is newer than \a timeStamp.
diff --git a/src/libs/utils/fileutils.h b/src/libs/utils/fileutils.h
index 5db3a0a1c2..9f1a0bef91 100644
--- a/src/libs/utils/fileutils.h
+++ b/src/libs/utils/fileutils.h
@@ -189,6 +189,8 @@ public:
                                 const FilePath &tgtFilePath,
                                 QString *error,
                                 T &&copyHelper);
+    static bool copyIfDifferent(const FilePath &srcFilePath,
+                                const FilePath &tgtFilePath);
     static FilePath resolveSymlinks(const FilePath &path);
     static QString fileSystemFriendlyName(const QString &name);
     static int indexOfQmakeUnfriendly(const QString &name, int startpos = 0);
diff --git a/src/plugins/cmakeprojectmanager/fileapidataextractor.cpp b/src/plugins/cmakeprojectmanager/fileapidataextractor.cpp
index badf74c059..2ca34b68ad 100644
--- a/src/plugins/cmakeprojectmanager/fileapidataextractor.cpp
+++ b/src/plugins/cmakeprojectmanager/fileapidataextractor.cpp
@@ -348,10 +348,15 @@ RawProjectParts generateRawProjectParts(const PreprocessedData &input,
             }
 
             QString ending;
-            if (ci.language == "C")
+            QString qtcPchFile;
+            if (ci.language == "C") {
                 ending = "/cmake_pch.h";
-            else if (ci.language == "CXX")
+                qtcPchFile = "qtc_cmake_pch.h";
+            }
+            else if (ci.language == "CXX") {
                 ending = "/cmake_pch.hxx";
+                qtcPchFile = "qtc_cmake_pch.hxx";
+            }
 
             ++counter;
             RawProjectPart rpp;
@@ -362,13 +367,7 @@ RawProjectParts generateRawProjectParts(const PreprocessedData &input,
             rpp.setMacros(transform<QVector>(ci.defines, &DefineInfo::define));
             rpp.setHeaderPaths(transform<QVector>(ci.includes, &IncludeInfo::path));
 
-            RawProjectPartFlags cProjectFlags;
-            cProjectFlags.commandLineFlags = splitFragments(ci.fragments);
-            rpp.setFlagsForC(cProjectFlags);
-
-            RawProjectPartFlags cxxProjectFlags;
-            cxxProjectFlags.commandLineFlags = cProjectFlags.commandLineFlags;
-            rpp.setFlagsForCxx(cxxProjectFlags);
+            QStringList fragments = splitFragments(ci.fragments);
 
             FilePath precompiled_header
                 = FilePath::fromString(findOrDefault(t.sources, [&ending](const SourceInfo &si) {
@@ -383,9 +382,38 @@ RawProjectParts generateRawProjectParts(const PreprocessedData &input,
                     const FilePath parentDir = FilePath::fromString(sourceDir.absolutePath());
                     precompiled_header = parentDir.pathAppended(precompiled_header.toString());
                 }
-                rpp.setPreCompiledHeaders({precompiled_header.toString()});
+
+                // Remove the CMake PCH usage command line options in order to avoid the case
+                // when the build system would produce a .pch/.gch file that would be treated
+                // by the Clang code model as its own and fail.
+                auto remove = [&](const QStringList &args) {
+                    auto foundPos = std::search(fragments.begin(), fragments.end(),
+                                                args.begin(), args.end());
+                    if (foundPos != fragments.end())
+                        fragments.erase(foundPos, std::next(foundPos, args.size()));
+                };
+
+                remove({"-Xclang", "-include-pch", "-Xclang", precompiled_header.toString() + ".gch"});
+                remove({"-Xclang", "-include-pch", "-Xclang", precompiled_header.toString() + ".pch"});
+                remove({"-Xclang", "-include", "-Xclang", precompiled_header.toString()});
+                remove({"-include", precompiled_header.toString()});
+                remove({"/FI", precompiled_header.toString()});
+
+                // Make a copy of the CMake PCH header and use it instead
+                FilePath qtc_precompiled_header = precompiled_header.parentDir().pathAppended(qtcPchFile);
+                FileUtils::copyIfDifferent(precompiled_header, qtc_precompiled_header);
+
+                rpp.setPreCompiledHeaders({qtc_precompiled_header.toString()});
             }
 
+            RawProjectPartFlags cProjectFlags;
+            cProjectFlags.commandLineFlags = fragments;
+            rpp.setFlagsForC(cProjectFlags);
+
+            RawProjectPartFlags cxxProjectFlags;
+            cxxProjectFlags.commandLineFlags = cProjectFlags.commandLineFlags;
+            rpp.setFlagsForCxx(cxxProjectFlags);
+
             const bool isExecutable = t.type == "EXECUTABLE";
             rpp.setBuildTargetType(isExecutable ? ProjectExplorer::BuildTargetType::Executable
                                                 : ProjectExplorer::BuildTargetType::Library);
diff --git a/src/plugins/cpptools/compileroptionsbuilder.cpp b/src/plugins/cpptools/compileroptionsbuilder.cpp
index 02ce9a3616..37d64208b1 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.cpp
+++ b/src/plugins/cpptools/compileroptionsbuilder.cpp
@@ -175,14 +175,6 @@ void CompilerOptionsBuilder::addSyntaxOnly()
     isClStyle() ? add("/Zs") : add("-fsyntax-only");
 }
 
-void CompilerOptionsBuilder::remove(const QStringList &args)
-{
-    auto foundPos = std::search(m_options.begin(), m_options.end(),
-                                args.begin(), args.end());
-    if (foundPos != m_options.end())
-        m_options.erase(foundPos, std::next(foundPos, args.size()));
-}
-
 QStringList createLanguageOptionGcc(ProjectFile::Kind fileKind, bool objcExt)
 {
     QStringList options;
@@ -369,42 +361,32 @@ void CompilerOptionsBuilder::addHeaderPathOptions()
     }
 }
 
-void CompilerOptionsBuilder::addIncludedFiles(const QStringList &files)
+void CompilerOptionsBuilder::addIncludeFile(const QString &file)
 {
-    QStringList result;
+    if (QFile::exists(file)) {
+        add({isClStyle() ? QLatin1String(includeFileOptionCl)
+                         : QLatin1String(includeFileOptionGcc),
+             QDir::toNativeSeparators(file)});
+    }
+}
 
-    const QString includeOptionString
-            = QLatin1String(isClStyle() ? includeFileOptionCl : includeFileOptionGcc);
+void CompilerOptionsBuilder::addIncludedFiles(const QStringList &files)
+{
     for (const QString &file : files) {
-        if (QFile::exists(file)) {
-            result += includeOptionString;
-            result += QDir::toNativeSeparators(file);
-        }
+        if (m_projectPart.precompiledHeaders.contains(file))
+            continue;
+
+        addIncludeFile(file);
     }
-    m_options.append(result);
 }
 
 void CompilerOptionsBuilder::addPrecompiledHeaderOptions(UsePrecompiledHeaders usePrecompiledHeaders)
 {
+    if (usePrecompiledHeaders == UsePrecompiledHeaders::No)
+        return;
+
     for (const QString &pchFile : m_projectPart.precompiledHeaders) {
-        // Bail if build system precompiled header artifacts exists.
-        // Clang cannot handle foreign PCH files.
-        if (QFile::exists(pchFile + ".gch") || QFile::exists(pchFile + ".pch"))
-            usePrecompiledHeaders = UsePrecompiledHeaders::No;
-
-        if (usePrecompiledHeaders == UsePrecompiledHeaders::No) {
-            // CMake PCH will already have force included the header file in
-            // command line options, remove it if exists.
-            // In case of Clang compilers, also remove the pch-inclusion arguments.
-            remove({"-Xclang", "-include-pch", "-Xclang", pchFile + ".gch"});
-            remove({"-Xclang", "-include-pch", "-Xclang", pchFile + ".pch"});
-            remove({isClStyle() ? QLatin1String(includeFileOptionCl)
-                                : QLatin1String(includeFileOptionGcc), pchFile});
-        } else if (QFile::exists(pchFile)) {
-            add({isClStyle() ? QLatin1String(includeFileOptionCl)
-                             : QLatin1String(includeFileOptionGcc),
-                 QDir::toNativeSeparators(pchFile)});
-        }
+        addIncludeFile(pchFile);
     }
 }
 
diff --git a/src/plugins/cpptools/compileroptionsbuilder.h b/src/plugins/cpptools/compileroptionsbuilder.h
index d28c081258..f81c515db0 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.h
+++ b/src/plugins/cpptools/compileroptionsbuilder.h
@@ -88,8 +88,6 @@ public:
     void add(const QStringList &args, bool gccOnlyOptions = false);
     virtual void addExtraOptions() {}
 
-    void remove(const QStringList &args);
-
     static UseToolchainMacros useToolChainMacros();
     void reset();
 
@@ -103,6 +101,7 @@ private:
     QStringList wrappedQtHeadersIncludePath() const;
     QStringList wrappedMingwHeadersIncludePath() const;
     QByteArray msvcVersion() const;
+    void addIncludeFile(const QString &file);
 
 private:
     const ProjectPart &m_projectPart;