loplugin:unnecessarygetstr fix false +

encountering when we need to pass a std::string to an OString

Change-Id: I91d2aa1f20e7c2407c708c9ce4ae82fb52934c85
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152526
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 21 insertions, 7 deletions

diff --git a/compilerplugins/clang/test/unnecessarygetstr.cxx b/compilerplugins/clang/test/unnecessarygetstr.cxx
index bb5fcc20d2ef..c0960557a89b 100644
--- a/compilerplugins/clang/test/unnecessarygetstr.cxx
+++ b/compilerplugins/clang/test/unnecessarygetstr.cxx
@@ -11,6 +11,7 @@
 
 #include <ostream>
 #include <string_view>
+#include <string>
 
 #include <rtl/strbuf.hxx>
 #include <rtl/string.hxx>
@@ -120,4 +121,11 @@ void test(std::string v, OString o)
 }
 }
 
+// no warning expected
+namespace test6
+{
+void foo(const OString&);
+void test(std::string v) { foo(v.c_str()); }
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/unnecessarygetstr.cxx b/compilerplugins/clang/unnecessarygetstr.cxx
index 681070356108..c80877a78554 100644
--- a/compilerplugins/clang/unnecessarygetstr.cxx
+++ b/compilerplugins/clang/unnecessarygetstr.cxx
@@ -49,7 +49,8 @@ public:
                 .Namespace("rtl")
                 .GlobalNamespace())
         {
-            checkForGetStr(callExpr->getArg(0), "OUString::createFromAscii");
+            checkForGetStr(callExpr->getArg(0), "OUString::createFromAscii",
+                           /*isOStringConstructor*/ false);
         }
         return true;
     }
@@ -62,22 +63,26 @@ public:
         if (tc.ClassOrStruct("basic_string").StdNamespace())
         {
             if (constructExpr->getNumArgs() == 1 || constructExpr->getNumArgs() == 2)
-                checkForGetStr(constructExpr->getArg(0), "string constructor");
+                checkForGetStr(constructExpr->getArg(0), "string constructor",
+                               /*isOStringConstructor*/ false);
         }
         else if (tc.ClassOrStruct("basic_string_view").StdNamespace())
         {
             if (constructExpr->getNumArgs() == 1)
-                checkForGetStr(constructExpr->getArg(0), "string_view constructor");
+                checkForGetStr(constructExpr->getArg(0), "string_view constructor",
+                               /*isOStringConstructor*/ false);
         }
         else if (tc.Class("OString").Namespace("rtl").GlobalNamespace())
         {
             if (constructExpr->getNumArgs() == 1 || constructExpr->getNumArgs() == 2)
-                checkForGetStr(constructExpr->getArg(0), "OString constructor");
+                checkForGetStr(constructExpr->getArg(0), "OString constructor",
+                               /*isOStringConstructor*/ true);
         }
         else if (tc.Class("OUString").Namespace("rtl").GlobalNamespace())
         {
             if (constructExpr->getNumArgs() == 2)
-                checkForGetStr(constructExpr->getArg(0), "OUString constructor");
+                checkForGetStr(constructExpr->getArg(0), "OUString constructor",
+                               /*isOStringConstructor*/ false);
         }
         return true;
     }
@@ -94,7 +99,7 @@ public:
     }
 
 private:
-    void checkForGetStr(const Expr* arg, const char* msg)
+    void checkForGetStr(const Expr* arg, const char* msg, bool isOStringConstructor)
     {
         auto e = dyn_cast<CXXMemberCallExpr>(arg->IgnoreImplicit());
         if (!e)
@@ -117,7 +122,8 @@ private:
                         << msg << e->getSourceRange();
             }
         }
-        else if (tc2.Class("basic_string").StdNamespace())
+        // we do need to use c_str() when passing to an OString
+        else if (!isOStringConstructor && tc2.Class("basic_string").StdNamespace())
         {
             if (loplugin::DeclCheck(e->getMethodDecl()).Function("c_str"))
                 report(DiagnosticsEngine::Warning, "unnecessary call to 'c_str' when passing to %0",