[ASTImporter] Support for importing UsingDecl and UsingShadowDecl

[khazem]

Summary

Some of this patch comes from Aleksei's branch [1], with minor revisions. I've added unit tests and AST Matcher support. Copying in Manuel in case there is no need for a dedicated usingShadowDecl() matcher, in which case I could define it only in the test suite.

This patch depends on D26753.

[1] https://github.com/haoNoQ/clang/blob/summary-ipa-draft/lib/AST/ASTImporter.cpp#L3594

[klimek]

Can you add a test to ASTMatchersNodeTests.cpp? Otherwise LG for the matcher parts.

[a.sidorin]

Thank you Kareem, It looks mostly good, but I'd like to have some functional tests in ASTMerge for this patch.

lib/AST/ASTImporter.cpp

4299 ↗

(On Diff #79488)

nullptr

4323 ↗

(On Diff #79488)

This will assert if import fails. We need to use cast_or_null and check for null returns. (If this is the result of my misleading code, sorry for this.)

4335 ↗

(On Diff #79488)

nullptr

4342 ↗

(On Diff #79488)

This will assert if import fails. We need to use cast_or_null and check for null returns.

[spyffe]

Looks good, but I have a concern about the underlying branch's apparently inconsistent initialization of DeclarationNameInfo. Aleksei, could you clarify how that code works? Should we have a helper function so we don't have to carefully repeat this pattern everywhere?

lib/AST/ASTImporter.cpp

4305 ↗

(On Diff #79488)

I've seen this pattern before, in D20733, at ASTImporter.cpp:6488:

DeclarationNameInfo NameInfo(E->getName(), E->getNameLoc());
ImportDeclarationNameLoc(E->getNameInfo(), NameInfo);

That code didn't do the Import during the initialization of the DeclarationNameInfo. Is either of these incorrect?

[a.sidorin]

lib/AST/ASTImporter.cpp

4305 ↗

(On Diff #79488)

This may come from our published code but it looks like an issue that needs to be fixed. Thank you for spotting this.

[a.sidorin]

Hello Kareem,

While the functionality of this patch is already implemented in my already merged patch, I added your tests into the repo. Thank you!

cfe/trunk/unittests/AST/ASTImporterTest.cpp

EXPECT_TRUE(
                  "  T t;"
                  "  p->T::~T();"
                  "}",
                  Lang_CXX, "", Lang_CXX, Verifier,
                  functionDecl(has(compoundStmt(has(
                      callExpr(has(cxxPseudoDestructorExpr()))))))));
 }
 
+TEST(ImportDecl, ImportUsingDecl) {
+  MatchVerifier<Decl> Verifier;
+  EXPECT_TRUE(
+        testImport(
+          "namespace foo { int bar; }"
+          "int declToImport(){ using foo::bar; }",
+          Lang_CXX, "", Lang_CXX, Verifier,
+          functionDecl(
+            has(
+              compoundStmt(
+                has(
+                  declStmt(
+                    has(
+                      usingDecl()))))))));
+}
+
+/// \brief Matches shadow declarations introduced into a scope by a
+///        (resolved) using declaration.
+///
+/// Given
+/// \code
+///   namespace n { int f; }
+///   namespace declToImport { using n::f; }
+/// \endcode
+/// usingShadowDecl()
+///   matches \code f \endcode
+const internal::VariadicDynCastAllOfMatcher<Decl,
+                                            UsingShadowDecl> usingShadowDecl;
+
+TEST(ImportDecl, ImportUsingShadowDecl) {
+  MatchVerifier<Decl> Verifier;
+  EXPECT_TRUE(
+        testImport(
+          "namespace foo { int bar; }"
+          "namespace declToImport { using foo::bar; }",
+          Lang_CXX, "", Lang_CXX, Verifier,
+          namespaceDecl(
+            has(
+              usingShadowDecl()))));
+}
+
 } // end namespace ast_matchers
 } // end namespace clang