Fix C++ Library wizard when compiled with Qt < 5.12

Only Qt 5.12 got true ECMA Script capabilities, so arrow function
expressions are not supported before that.

To be able to use "regular" inline functions, we allow usage of } by escaping with backslash.
For variables that do not start with "JS:" we already supported backslash for escaping.

Fixes: QTCREATORBUG-22336
Change-Id: I9fc638e64d2757a21fffc16355635e2fcff87a36
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

5 files changed, 17 insertions, 5 deletions

diff --git a/share/qtcreator/templates/wizards/projects/cpplibrary/lib.cpp b/share/qtcreator/templates/wizards/projects/cpplibrary/lib.cpp
index dcdacae6d3..6eb6c86faa 100644
--- a/share/qtcreator/templates/wizards/projects/cpplibrary/lib.cpp
+++ b/share/qtcreator/templates/wizards/projects/cpplibrary/lib.cpp
@@ -11,7 +11,7 @@
     : %{BaseClassName}(parent)
 {
 }
-%{JS: '%{PluginMethods}'.split('|').map(s => '\n' + s.replace(/([a-zA-Z0-9]+\()/, '%{CN}::$1') + '\n\u007B\n    static_assert(false, "You need to implement this function");\n\u007D').join('\n')}\
+%{JS: '%{PluginMethods}'.split('|').map(function(s) { return '\\n' + s.replace(/([a-zA-Z0-9]+\\()/, '%{CN}::$1') + '\\n\{\\n    static_assert(false, "You need to implement this function");\\n\}'; \}).join('\\n')}\
 
 @endif
 %{JS: Cpp.closeNamespaces('%{Class}')}\
diff --git a/share/qtcreator/templates/wizards/projects/cpplibrary/lib.h b/share/qtcreator/templates/wizards/projects/cpplibrary/lib.h
index 4a5d1247a4..ae2c90a313 100644
--- a/share/qtcreator/templates/wizards/projects/cpplibrary/lib.h
+++ b/share/qtcreator/templates/wizards/projects/cpplibrary/lib.h
@@ -36,7 +36,7 @@ public:
     explicit %{CN}(QObject *parent = nullptr);
 
 private:
-%{JS: '%{PluginMethods}'.split('|').map(s => '    ' + s + ' override;').join('\n')}
+%{JS: '%{PluginMethods}'.split('|').map(function(s) { return '    ' + s + ' override;'; \}).join('\\n')}
 };
 @endif
 %{JS: Cpp.closeNamespaces('%{Class}')}\
diff --git a/src/libs/utils/stringutils.cpp b/src/libs/utils/stringutils.cpp
index b39af367d5..161cf44e74 100644
--- a/src/libs/utils/stringutils.cpp
+++ b/src/libs/utils/stringutils.cpp
@@ -143,7 +143,7 @@ bool AbstractMacroExpander::expandNestedMacros(const QString &str, int *pos, QSt
     varName.reserve(strLen - i);
     for (; i < strLen; prev = c) {
         c = str.at(i++);
-        if (c == '\\' && i < strLen && validateVarName(varName)) {
+        if (c == '\\' && i < strLen) {
             c = str.at(i++);
             // For the replacement, do not skip the escape sequence when followed by a digit.
             // This is needed for enabling convenient capture group replacement,
diff --git a/src/plugins/coreplugin/jsexpander.cpp b/src/plugins/coreplugin/jsexpander.cpp
index 5aa9279c7c..4ee72752e5 100644
--- a/src/plugins/coreplugin/jsexpander.cpp
+++ b/src/plugins/coreplugin/jsexpander.cpp
@@ -111,7 +111,9 @@ void JsExpander::registerForExpander(Utils::MacroExpander *macroExpander)
         "JS",
         QCoreApplication::translate("Core::JsExpander",
                                     "Evaluate simple JavaScript statements.<br>"
-                                    "The statements may not contain '{' nor '}' characters."),
+                                    "Literal '}' characters must be escaped as \"\\}\", "
+                                    "'\\' characters must be escaped as \"\\\\\", "
+                                    "and \"%{\" must be escaped as \"%\\{\"."),
         [this](QString in) -> QString {
             QString errorMessage;
             QString result = evaluate(in, &errorMessage);
diff --git a/tests/auto/utils/stringutils/tst_stringutils.cpp b/tests/auto/utils/stringutils/tst_stringutils.cpp
index 8e51c89300..98e04185ab 100644
--- a/tests/auto/utils/stringutils/tst_stringutils.cpp
+++ b/tests/auto/utils/stringutils/tst_stringutils.cpp
@@ -68,6 +68,14 @@ public:
             *ret = "bar";
             return true;
         }
+        if (name == "JS:with } inside") {
+            *ret = "yay";
+            return true;
+        }
+        if (name == "JS:literal%{") {
+            *ret = "hurray";
+            return true;
+        }
         return false;
     }
 };
@@ -158,7 +166,9 @@ void tst_StringUtils::testMacroExpander_data()
         {"%{hihi//./c}", "ccc"},
         {"%{hihi/(.)(.)r/\\2\\1c}", "abc"}, // no escape for capture groups
         {"%{hihi/b/c/d}", "c/dar"},
-        {"%{hihi/a/e{\\}e}", "be{}er"}, // escape closing brace
+        {"%{hihi/a/e{\\}e}", "be{}er"},   // escape closing brace
+        {"%{JS:with \\} inside}", "yay"}, // escape closing brace also in JS:
+        {"%{JS:literal%\\{}", "hurray"},
         {"%{slash/o\\/b/ol's c}", "fool's car"},
         {"%{sl\\/sh/(.)(a)(.)/\\2\\1\\3as}", "salsash"}, // escape in variable name
         {"%{JS:foo/b/c}", "%{JS:foo/b/c}"}, // No replacement for JS (all considered varName)