Clang: Fix error when including float.h with mingw

Prevent mingw from trying to #include_next a private header from a path
we cannot add to our list of includes.

Fixes: QTCREATORBUG-24251
Task-number: QTCREATORBUG-24027
Change-Id: I18a9db130b9c2265cd208c3506d08d2e1c4cee45
Reviewed-by: Marco Bubke <marco.bubke@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

4 files changed, 104 insertions, 17 deletions

diff --git a/share/qtcreator/cplusplus/wrappedMingwHeaders/float.h b/share/qtcreator/cplusplus/wrappedMingwHeaders/float.h
new file mode 100644
index 0000000000..8edb202a80
--- /dev/null
+++ b/share/qtcreator/cplusplus/wrappedMingwHeaders/float.h
@@ -0,0 +1,34 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+// MinGW's "public" float.h includes a "private" float.h via #include_next.
+// We don't have access to the private header, because we cannot add its directory to
+// the list of include paths due to other headers in there that confuse clang.
+// Therefore, we prevent inclusion of the private header by setting a magic macro.
+// See also QTCREATORBUG-24251.
+#ifdef __MINGW32__ // Redundant, but let's play it safe.
+#define __FLOAT_H
+#include_next <float.h>
+#endif
diff --git a/src/plugins/cpptools/compileroptionsbuilder.cpp b/src/plugins/cpptools/compileroptionsbuilder.cpp
index 1e9568294a..a4aaa0bd32 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.cpp
+++ b/src/plugins/cpptools/compileroptionsbuilder.cpp
@@ -155,6 +155,7 @@ QStringList CompilerOptionsBuilder::build(ProjectFile::Kind fileKind,
     addExtraOptions();
 
     insertWrappedQtHeaders();
+    insertWrappedMingwHeaders();
 
     return options();
 }
@@ -285,6 +286,16 @@ void CompilerOptionsBuilder::enableExceptions()
     add("-fexceptions");
 }
 
+void CompilerOptionsBuilder::insertWrappedQtHeaders()
+{
+    insertWrappedHeaders(wrappedQtHeadersIncludePath());
+}
+
+void CompilerOptionsBuilder::insertWrappedMingwHeaders()
+{
+    insertWrappedHeaders(wrappedMingwHeadersIncludePath());
+}
+
 static QString creatorResourcePath()
 {
 #ifndef UNIT_TESTS
@@ -294,19 +305,26 @@ static QString creatorResourcePath()
 #endif
 }
 
-void CompilerOptionsBuilder::insertWrappedQtHeaders()
+void CompilerOptionsBuilder::insertWrappedHeaders(const QStringList &relPaths)
 {
     if (m_useTweakedHeaderPaths == UseTweakedHeaderPaths::No)
         return;
+    if (relPaths.isEmpty())
+        return;
 
-    QStringList wrappedQtHeaders;
-    addWrappedQtHeadersIncludePath(wrappedQtHeaders);
+    QStringList args;
+    for (const QString &relPath : relPaths) {
+        static const QString baseDir = creatorResourcePath() + "/cplusplus";
+        const QString fullPath = baseDir + '/' + relPath;
+        QTC_ASSERT(QDir(fullPath).exists(), continue);
+        args << includeUserPathOption << QDir::toNativeSeparators(fullPath);
+    }
 
     const int index = m_options.indexOf(QRegularExpression("\\A-I.*\\z"));
     if (index < 0)
-        add(wrappedQtHeaders);
+        add(args);
     else
-        m_options = m_options.mid(0, index) + wrappedQtHeaders + m_options.mid(index);
+        m_options = m_options.mid(0, index) + args + m_options.mid(index);
 }
 
 void CompilerOptionsBuilder::addHeaderPathOptions()
@@ -686,19 +704,18 @@ bool CompilerOptionsBuilder::excludeDefineDirective(const ProjectExplorer::Macro
     return false;
 }
 
-void CompilerOptionsBuilder::addWrappedQtHeadersIncludePath(QStringList &list) const
+QStringList CompilerOptionsBuilder::wrappedQtHeadersIncludePath() const
 {
-    static const QString resourcePath = creatorResourcePath();
-    static QString wrappedQtHeadersPath = resourcePath + "/cplusplus/wrappedQtHeaders";
-    QTC_ASSERT(QDir(wrappedQtHeadersPath).exists(), return;);
+    if (m_projectPart.qtVersion == Utils::QtVersion::None)
+        return {};
+    return {"wrappedQtHeaders", "wrappedQtHeaders/QtCore"};
+}
 
-    if (m_projectPart.qtVersion != Utils::QtVersion::None) {
-        const QString wrappedQtCoreHeaderPath = wrappedQtHeadersPath + "/QtCore";
-        list.append({includeUserPathOption,
-                     QDir::toNativeSeparators(wrappedQtHeadersPath),
-                     includeUserPathOption,
-                     QDir::toNativeSeparators(wrappedQtCoreHeaderPath)});
-    }
+QStringList CompilerOptionsBuilder::wrappedMingwHeadersIncludePath() const
+{
+    if (m_projectPart.toolchainType != ProjectExplorer::Constants::MINGW_TOOLCHAIN_TYPEID)
+        return {};
+    return {"wrappedMingwHeaders"};
 }
 
 void CompilerOptionsBuilder::addProjectConfigFileInclude()
diff --git a/src/plugins/cpptools/compileroptionsbuilder.h b/src/plugins/cpptools/compileroptionsbuilder.h
index b2c8313771..ee7e373312 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.h
+++ b/src/plugins/cpptools/compileroptionsbuilder.h
@@ -71,6 +71,7 @@ public:
     void addCompilerFlags();
     void enableExceptions();
     void insertWrappedQtHeaders();
+    void insertWrappedMingwHeaders();
     void addLanguageVersionAndExtensions();
     void updateFileLanguage(ProjectFile::Kind fileKind);
 
@@ -97,7 +98,9 @@ public:
 private:
     void addIncludeDirOptionForPath(const ProjectExplorer::HeaderPath &path);
     bool excludeDefineDirective(const ProjectExplorer::Macro &macro) const;
-    void addWrappedQtHeadersIncludePath(QStringList &list) const;
+    void insertWrappedHeaders(const QStringList &paths);
+    QStringList wrappedQtHeadersIncludePath() const;
+    QStringList wrappedMingwHeadersIncludePath() const;
     QByteArray msvcVersion() const;
 
 private:
diff --git a/tests/unit/unittest/compileroptionsbuilder-test.cpp b/tests/unit/unittest/compileroptionsbuilder-test.cpp
index 2a6bfd8462..76fe2be066 100644
--- a/tests/unit/unittest/compileroptionsbuilder-test.cpp
+++ b/tests/unit/unittest/compileroptionsbuilder-test.cpp
@@ -475,6 +475,39 @@ TEST_F(CompilerOptionsBuilder, InsertWrappedQtHeaders)
     ASSERT_THAT(compilerOptionsBuilder.options(), Contains(IsPartOfHeader("wrappedQtHeaders")));
 }
 
+TEST_F(CompilerOptionsBuilder, InsertWrappedMingwHeadersWithNonMingwToolchain)
+{
+    CppTools::CompilerOptionsBuilder builder{
+        projectPart,
+        CppTools::UseSystemHeader::Yes,
+        CppTools::UseTweakedHeaderPaths::Yes,
+        CppTools::UseLanguageDefines::No,
+        CppTools::UseBuildSystemWarnings::No,
+        "dummy_version",
+        ""};
+
+    builder.insertWrappedMingwHeaders();
+
+    ASSERT_THAT(builder.options(), Not(Contains(IsPartOfHeader("wrappedMingwHeaders"))));
+}
+
+TEST_F(CompilerOptionsBuilder, InsertWrappedMingwHeadersWithMingwToolchain)
+{
+    CppTools::CompilerOptionsBuilder builder{
+        projectPart,
+        CppTools::UseSystemHeader::Yes,
+        CppTools::UseTweakedHeaderPaths::Yes,
+        CppTools::UseLanguageDefines::No,
+        CppTools::UseBuildSystemWarnings::No,
+        "dummy_version",
+        ""};
+    projectPart.toolchainType = ProjectExplorer::Constants::MINGW_TOOLCHAIN_TYPEID;
+
+    builder.insertWrappedMingwHeaders();
+
+    ASSERT_THAT(builder.options(), Contains(IsPartOfHeader("wrappedMingwHeaders")));
+}
+
 TEST_F(CompilerOptionsBuilder, SetLanguageVersion)
 {
     compilerOptionsBuilder.updateFileLanguage(ProjectFile::CXXSource);