[PATCH] D54188: [Sema] Mark target of __attribute__((alias("target"))) used for C

[Nick Desaulniers via Phabricator via cfe-commits]

nickdesaulniers updated this revision to Diff 180932.
nickdesaulniers added a comment.

- add static keyword to test case


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54188/new/

https://reviews.llvm.org/D54188

Files:
  lib/Sema/SemaDeclAttr.cpp
  test/Sema/alias-unused.c


Index: test/Sema/alias-unused.c
===================================================================
--- /dev/null
+++ test/Sema/alias-unused.c
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -Wunneeded-internal-declaration -x c -verify %s
+// expected-no-diagnostics
+static int f() { return 42; }
+int g() __attribute__((alias("f")));
+
+static int foo [] = { 42, 0xDEAD };
+extern typeof(foo) bar __attribute__((unused, alias("foo")));
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -1898,7 +1898,16 @@
     }
   }
 
-  // FIXME: check if target symbol exists in current file
+  // Mark target used to prevent unneeded-internal-declaration warnings.
+  if (!S.LangOpts.CPlusPlus) {
+    // FIXME: demangle Str for C++, as the attribute refers to the mangled
+    // linkage name, not the pre-mangled identifier.
+    const DeclarationNameInfo target(&S.Context.Idents.get(Str), AL.getLoc());
+    LookupResult LR(S, target, Sema::LookupOrdinaryName);
+    if (S.LookupQualifiedName(LR, S.getCurLexicalContext()))
+      for (NamedDecl *ND : LR)
+        ND->markUsed(S.Context);
+  }
 
   D->addAttr(::new (S.Context) AliasAttr(AL.getRange(), S.Context, Str,
                                          AL.getAttributeSpellingListIndex()));


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