fixed #14347 - fixed Clang warnings in C++20 build

.github/workflows/CI-unixish.yml

@@ -196,7 +196,16 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-22.04, macos-15]
-        cxxstd: [14, 17]
+        cxxstd: [14, 17, 20]
+        # FIXME: macos-15 fails to compile with C++20
+        #
+        # /Users/runner/work/cppcheck/cppcheck/cmake.output/gui/test/projectfile/moc_testprojectfile.cpp:84:1: error: 'constinit' specifier is incompatible with C++ standards before C++20 [-Werror,-Wc++20-compat]
+        #    84 | Q_CONSTINIT const QMetaObject TestProjectFile::staticMetaObject = { {
+        #       | ^
+        # /opt/homebrew/opt/qt/lib/QtCore.framework/Headers/qcompilerdetection.h:1409:23: note: expanded from macro 'Q_CONSTINIT'
+        exclude:
+          - os: macos-15
+            cxxstd: 20
       fail-fast: false # Prefer quick result
 
     runs-on: ${{ matrix.os }}

.github/workflows/CI-windows.yml

@@ -75,7 +75,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-2022, windows-2025]
-        cxxstd: [14, 17]
+        cxxstd: [14, 17, 20]
       fail-fast: false
 
     runs-on: ${{ matrix.os }}

gui/resultstree.cpp

@@ -22,6 +22,7 @@
 #include "applicationlist.h"
 #include "checkers.h"
 #include "common.h"
+#include "config.h"
 #include "erroritem.h"
 #include "errorlogger.h"
 #include "errortypes.h"
@@ -713,15 +714,15 @@ void ResultsTree::contextMenuEvent(QContextMenuEvent * e)
                 {
                     auto *action = new QAction(tr("No tag"), tagMenu);
                     tagMenu->addAction(action);
-                    connect(action, &QAction::triggered, [=]() {
+                    connect(action, &QAction::triggered, [EXPLICIT_THIS]() {
                         tagSelectedItems(QString());
                     });
                 }
 
                 for (const QString& tagstr : currentProject->getTags()) {
                     auto *action = new QAction(tagstr, tagMenu);
                     tagMenu->addAction(action);
-                    connect(action, &QAction::triggered, [=]() {
+                    connect(action, &QAction::triggered, [EXPLICIT_THIS]() {
                         tagSelectedItems(tagstr);
                     });
                 }

lib/config.h

@@ -131,6 +131,12 @@
 #  define RET_NONNULL
 #endif
 
+#if __cplusplus >= 202002L
+#  define EXPLICIT_THIS =, this
+#else
+#  define EXPLICIT_THIS =
+#endif
+
 #define REQUIRES(msg, ...) class=typename std::enable_if<__VA_ARGS__::value>::type
 
 // Use the nonneg macro when you want to assert that a variable/argument is not negative

lib/pathmatch.cpp

@@ -33,7 +33,7 @@ PathMatch::PathMatch(std::vector<std::string> patterns, std::string basepath, Sy
 
 bool PathMatch::match(const std::string &path, Filemode mode) const
 {
-    return std::any_of(mPatterns.cbegin(), mPatterns.cend(), [=] (const std::string &pattern) {
+    return std::any_of(mPatterns.cbegin(), mPatterns.cend(), [&] (const std::string &pattern) {
         return match(pattern, path, mBasepath, mode, mSyntax);
     });
 }