loplugin:stringconstant: Catch some O[U]String::getStr anti-patterns

Change-Id: I36bc86fcffc3c10fe44e60d779c9aa48eeed00f2
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154749
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 56 insertions, 0 deletions

diff --git a/compilerplugins/clang/stringconstant.cxx b/compilerplugins/clang/stringconstant.cxx
index cf1eb6afedbf..c64c2c9d6589 100644
--- a/compilerplugins/clang/stringconstant.cxx
+++ b/compilerplugins/clang/stringconstant.cxx
@@ -191,6 +191,8 @@ public:
 
     bool VisitCallExpr(CallExpr const * expr);
 
+    bool VisitCXXMemberCallExpr(CXXMemberCallExpr const * expr);
+
     bool VisitCXXConstructExpr(CXXConstructExpr const * expr);
 
     bool VisitReturnStmt(ReturnStmt const * stmt);
@@ -856,6 +858,47 @@ bool StringConstant::VisitCallExpr(CallExpr const * expr) {
     return true;
 }
 
+bool StringConstant::VisitCXXMemberCallExpr(CXXMemberCallExpr const * expr) {
+    if (ignoreLocation(expr)) {
+        return true;
+    }
+    FunctionDecl const * fdecl = expr->getDirectCallee();
+    if (fdecl == nullptr) {
+        return true;
+    }
+    auto const c = loplugin::DeclCheck(fdecl).Function("getStr");
+    if ((c.Class("OString").Namespace("rtl").GlobalNamespace()
+         || c.Class("OUString").Namespace("rtl").GlobalNamespace())
+        && fdecl->getNumParams() == 0)
+    {
+        auto const e1 = expr->getImplicitObjectArgument()->IgnoreImplicit()->IgnoreParens();
+        if (auto const e2 = dyn_cast<CXXTemporaryObjectExpr>(e1)) {
+            if (e2->getNumArgs() != 0) {
+                return true;
+            }
+            report(
+                DiagnosticsEngine::Warning,
+                "in call of '%0', replace default-constructed %1 directly with an empty %select{ordinary|UTF-16}2 string literal",
+                expr->getExprLoc())
+                << fdecl->getQualifiedNameAsString() << e2->getType() << bool(loplugin::TypeCheck(e2->getType()).Class("OUString")) << expr->getSourceRange();
+            return true;
+        }
+        if (auto const e2 = dyn_cast<CXXFunctionalCastExpr>(e1)) {
+            auto const e3 = dyn_cast<clang::StringLiteral>(e2->getSubExprAsWritten()->IgnoreParens());
+            if (e3 == nullptr) {
+                return true;
+            }
+            report(
+                DiagnosticsEngine::Warning,
+                "in call of '%0', replace %1 constructed from a string literal directly with %select{the|a UTF-16}2 string literal",
+                expr->getExprLoc())
+                << fdecl->getQualifiedNameAsString() << e2->getType() << (loplugin::TypeCheck(e2->getType()).Class("OUString") && !e3->isUTF16()) << expr->getSourceRange();
+            return true;
+        }
+    }
+    return true;
+}
+
 bool StringConstant::VisitCXXConstructExpr(CXXConstructExpr const * expr) {
     if (ignoreLocation(expr)) {
         return true;
diff --git a/compilerplugins/clang/test/stringconstant.cxx b/compilerplugins/clang/test/stringconstant.cxx
index 02f83b531068..ada901b877ce 100644
--- a/compilerplugins/clang/test/stringconstant.cxx
+++ b/compilerplugins/clang/test/stringconstant.cxx
@@ -128,6 +128,19 @@ int main() {
     ub.append(static_cast<char const *>(sc2)); // at runtime: append "foo"
     ub.append(static_cast<char const *>(sc3)); // at runtime: assert
     ub.append(static_cast<char const *>(sc4)); // at runtime: UB
+
+    // expected-error-re@+1 {{in call of 'rtl::OString::getStr', replace default-constructed '{{(rtl::)?}}OString' directly with an empty ordinary string literal}}
+    OString().getStr();
+    // expected-error-re@+1 {{in call of 'rtl::OString::getStr', replace '{{(rtl::)?}}OString' constructed from a string literal directly with the string literal}}
+    OString("foo").getStr();
+    // expected-error-re@+1 {{in call of 'rtl::OString::getStr', replace '{{(rtl::)?}}OString' constructed from a string literal directly with the string literal}}
+    (OString(("foo"))).getStr();
+    // expected-error-re@+1 {{in call of 'rtl::OUString::getStr', replace default-constructed '{{(rtl::)?}}OUString' directly with an empty UTF-16 string literal}}
+    OUString().getStr();
+    // expected-error-re@+1 {{in call of 'rtl::OUString::getStr', replace '{{(rtl::)?}}OUString' constructed from a string literal directly with a UTF-16 string literal}}
+    OUString("foo").getStr();
+    // expected-error-re@+1 {{in call of 'rtl::OUString::getStr', replace '{{(rtl::)?}}OUString' constructed from a string literal directly with the string literal}}
+    OUString(u"foo").getStr();
 }