readability-redundant-declarations: Fix crash

[danielmarjamaki]

Summary

This patch fixes a crash reported by Miklos Vajna

The testcase output without the fix:

******************** TEST 'Clang Tools :: clang-tidy/readability-redundant-declaration.cpp' FAILED ********************
Script:
--
/usr/bin/python2.7 /home/danielm/llvm/tools/clang/tools/extra/test/../test/clang-tidy/check_clang_tidy.py /home/danielm/llvm/tools/clang/tools/extra/test/clang-tidy/readability-redundant-declaration.cpp readability-redundant-declaration /home/danielm/llvm/build/tools/clang/tools/extra/test/clang-tidy/Output/readability-redundant-declaration.cpp.tmp
--
Exit Code: 1

Command Output (stdout):
--
Running ['clang-tidy', '/home/danielm/llvm/build/tools/clang/tools/extra/test/clang-tidy/Output/readability-redundant-declaration.cpp.tmp.cpp', '-fix', '--checks=-*,readability-redundant-declaration', '--', '--std=c++11']...
clang-tidy failed:
clang-tidy: /home/danielm/llvm/tools/clang/tools/extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp:183: clang::DiagnosticBuilder clang::tidy::ClangTidyContext::diag(llvm::StringRef, clang::SourceLocation, llvm::StringRef, clang::DiagnosticIDs::Level): Assertion `Loc.isValid()' failed.


--
Command Output (stderr):
--
Traceback (most recent call last):
  File "/home/danielm/llvm/tools/clang/tools/extra/test/../test/clang-tidy/check_clang_tidy.py", line 135, in <module>
    main()
  File "/home/danielm/llvm/tools/clang/tools/extra/test/../test/clang-tidy/check_clang_tidy.py", line 91, in main
    subprocess.check_output(args, stderr=subprocess.STDOUT).decode()
  File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command '['clang-tidy', '/home/danielm/llvm/build/tools/clang/tools/extra/test/clang-tidy/Output/readability-redundant-declaration.cpp.tmp.cpp', '-fix', '--checks=-*,readability-redundant-declaration', '--', '--std=c++11']' returned non-zero exit status -6

--

[hokein]

LGTM with a nit.

clang-tidy/readability/RedundantDeclarationCheck.cpp

33

Maybe put this statement in front of if (Prev->getLocation() == D->getLocation())?

clang-tidy/readability/RedundantDeclarationCheck.cpp

 
 void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
   const NamedDecl *D = Result.Nodes.getNodeAs<NamedDecl>("Decl");
   const auto *Prev = D->getPreviousDecl();
   if (!Prev)
     return;
   if (Prev->getLocation() == D->getLocation())
     return;
+  if (!Prev->getLocation().isValid())
+    return;
 
   const SourceManager &SM = *Result.SourceManager;
 
   const bool DifferentHeaders =
       !SM.isInMainFile(D->getLocation()) &&
       !SM.isWrittenInSameFile(Prev->getLocation(), D->getLocation());
 
   bool MultiVar = false;

test/clang-tidy/readability-redundant-declaration.cpp

 // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'Buf' declaration
 // CHECK-FIXES: {{^}}{{$}}
 
 static int f();
 static int f();
 // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: redundant 'f' declaration
 // CHECK-FIXES: {{^}}{{$}}
 static int f() {}
+
+// Original check crashed for the code below.
+namespace std {
+  typedef long unsigned int size_t;
+}
+void* operator new(std::size_t) __attribute__((__externally_visible__));
+void* operator new[](std::size_t) __attribute__((__externally_visible__));