Improve loplugin:stringview diagnostic output

Say what the O[U]String is constructed from (to make it easier to decide on an
optimal rephrase of the whole surrounding expression), and find more cases that
could use O[U]StringChar.

Change-Id: I64a3851544498c26ca3f46f5df7f593d2fdcb0ee
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/115579
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 40 insertions, 20 deletions

diff --git a/compilerplugins/clang/stringview.cxx b/compilerplugins/clang/stringview.cxx
index 95d7d6368572..cc717079732f 100644
--- a/compilerplugins/clang/stringview.cxx
+++ b/compilerplugins/clang/stringview.cxx
@@ -165,6 +165,7 @@ void StringView::handleSubExprThatCouldBeView(Expr const* subExpr)
 
 void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
 {
+    QualType argType;
     bool charArg = false;
     auto const d = expr->getConstructor();
     switch (d->getNumParams())
@@ -176,6 +177,7 @@ void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
             auto const t = d->getParamDecl(0)->getType();
             if (t->isAnyCharacterType())
             {
+                argType = expr->getArg(0)->IgnoreImplicit()->getType();
                 charArg = true;
                 break;
             }
@@ -194,6 +196,7 @@ void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
                 || tc.RvalueReference().Struct("OUStringNumber").Namespace("rtl").GlobalNamespace()
                 || tc.ClassOrStruct("basic_string_view").StdNamespace())
             {
+                argType = expr->getArg(0)->IgnoreImplicit()->getType();
                 break;
             }
             return;
@@ -207,6 +210,19 @@ void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
                 if (t->isIntegralType(compiler.getASTContext())
                     && !(t->isBooleanType() || t->isAnyCharacterType()))
                 {
+                    auto const arg = expr->getArg(1);
+                    if (!arg->isValueDependent())
+                    {
+                        if (auto const val
+                            = compat::getIntegerConstantExpr(arg, compiler.getASTContext()))
+                        {
+                            if (val->getExtValue() == 1)
+                            {
+                                charArg = true;
+                            }
+                        }
+                    }
+                    argType = expr->getArg(0)->IgnoreImplicit()->getType();
                     break;
                 }
             }
@@ -216,6 +232,7 @@ void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
                     .Namespace("rtl")
                     .GlobalNamespace())
             {
+                argType = expr->getArg(0)->IgnoreImplicit()->getType();
                 break;
             }
             return;
@@ -224,10 +241,11 @@ void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
             return;
     }
     report(DiagnosticsEngine::Warning,
-           "instead of an %0, pass a '%select{std::string_view|std::u16string_view}1'"
-           "%select{| (or an '%select{rtl::OStringChar|rtl::OUStringChar}1')}2",
+           "instead of an %0%select{| constructed from a %2}1, pass a"
+           " '%select{std::string_view|std::u16string_view}3'"
+           "%select{| (or an '%select{rtl::OStringChar|rtl::OUStringChar}3')}4",
            expr->getExprLoc())
-        << expr->getType()
+        << expr->getType() << (argType.isNull() ? 0 : 1) << argType
         << (loplugin::TypeCheck(expr->getType()).Class("OString").Namespace("rtl").GlobalNamespace()
                 ? 0
                 : 1)
diff --git a/compilerplugins/clang/test/stringview.cxx b/compilerplugins/clang/test/stringview.cxx
index 142bba799008..edd2305f2c69 100644
--- a/compilerplugins/clang/test/stringview.cxx
+++ b/compilerplugins/clang/test/stringview.cxx
@@ -102,41 +102,43 @@ void f5(char const* s1, sal_Int32 n1, char16_t const* s2, sal_Int32 n2)
 {
     // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString());
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'const char [4]', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString("foo"));
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' (or an 'rtl::OStringChar') [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'const char', pass a 'std::string_view' (or an 'rtl::OStringChar') [loplugin:stringview]}}
     call_view(OString(*s1));
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'const char *', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString(s1));
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'const char *', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString(s1, n1));
     constexpr OStringLiteral l1("foo");
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'const rtl::OStringLiteral<4>', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString(l1));
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'std::string_view' (aka 'basic_string_view<char>'), pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString(std::string_view("foo")));
-    // expected-error@+1 {{instead of an 'rtl::OString', pass a 'std::string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OString' constructed from a 'OStringNumber<int>', pass a 'std::string_view' [loplugin:stringview]}}
     call_view(OString(OString::number(0)));
     // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString());
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char [4]', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString("foo"));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char16_t [4]', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(u"foo"));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' (or an 'rtl::OUStringChar') [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char', pass a 'std::u16string_view' (or an 'rtl::OUStringChar') [loplugin:stringview]}}
     call_view(OUString(*s1));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' (or an 'rtl::OUStringChar') [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char16_t', pass a 'std::u16string_view' (or an 'rtl::OUStringChar') [loplugin:stringview]}}
     call_view(OUString(*s2));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char16_t *', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(s2));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char16_t *', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(s2, n2));
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const char16_t *', pass a 'std::u16string_view' (or an 'rtl::OUStringChar') [loplugin:stringview]}}
+    call_view(OUString(s2, 1));
     constexpr OUStringLiteral l2(u"foo");
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'const rtl::OUStringLiteral<4>', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(l2));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'std::u16string_view' (aka 'basic_string_view<char16_t>'), pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(std::u16string_view(u"foo")));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'OUStringNumber<int>', pass a 'std::u16string_view' [loplugin:stringview]}}
     call_view(OUString(OUString::number(0)));
 }
 
@@ -148,7 +150,7 @@ void f5(OUString s)
     buf = s.copy(5);
     // expected-error@+1 {{rather than copy, pass with a view using subView() [loplugin:stringview]}}
     buf.append(s.copy(12));
-    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    // expected-error@+1 {{instead of an 'rtl::OUString' constructed from a 'std::u16string_view' (aka 'basic_string_view<char16_t>'), pass a 'std::u16string_view' [loplugin:stringview]}}
     buf.append(OUString(std::u16string_view(u"foo")));
 }