[lldb] Fix name lookup in ClangASTContext

[evgeny777]

Summary

The check for already searched namespaces has disappeared from DeclContextFindDeclByName() recently. This breaks variable evaluation in many cases, for example in this one

namespace ns1 {
    int var = 100;
}

namespace ns2 {
    int var = 101;
}

int main(void) {
    {
        using namespace ns1;
        printf("var=%d\n", var); // evaluation fails - multiple candidates
    }

    {
        using namespace ns2;
        printf("var=%d\n", var); // evaluation fails - multiple candidates
    }
}

[tberghammer]

Please create a test case for this scenario so it won't break again

[evgeny777]

Added test case

[tberghammer]

Te test case looks good to me. Thanks for adding it.

For the actual code change I don' know enough about this area to say anything so please wait for a feedback from Greg.

[dawn]

Patch is correct - without it we loop through the same decl context again. I've tested it locally - there are no new regressions.

[dawn]

See inline comment.

source/Symbol/ClangASTContext.cpp

9191

Minor efficiency improvement - change these 3 lines to:

if (!searched.insert(it->second).first)
    continue;

No need for new patch - just change in final commit.

packages/Python/lldbsuite/test/lang/cpp/namespace/TestNamespace.py

def setUp(self):
         # Find the line numbers for declarations of namespace variables i and j.
         self.line_var_i = line_number('main.cpp',
                 '// Find the line number for anonymous namespace variable i.')
         self.line_var_j = line_number('main.cpp',
                 '// Find the line number for named namespace variable j.')
         # And the line number to break at.
         self.line_break = line_number('main.cpp',
                 '// Set break point at this line.')
+        # Break inside do {} while and evaluate value
+        self.line_break_ns1 = line_number('main.cpp', '// Evaluate ns1::value')
+        self.line_break_ns2 = line_number('main.cpp', '// Evaluate ns2::value')
+
+    def runToBkpt(self, command):
+        self.runCmd(command, RUN_SUCCEEDED)
+        # The stop reason of the thread should be breakpoint.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'stop reason = breakpoint'])
 
     # rdar://problem/8668674
     @expectedFailureWindows("llvm.org/pr24764")
     def test_with_run_command(self):
         """Test that anonymous and named namespace variables display correctly."""
         self.build()
         self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
 
+        lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line_break_ns1, num_expected_locations=1, loc_exact=True)
+        lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line_break_ns2, num_expected_locations=1, loc_exact=True)
         lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line_break, num_expected_locations=1, loc_exact=True)
 
-        self.runCmd("run", RUN_SUCCEEDED)
-
-        # The stop reason of the thread should be breakpoint.
-        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
-            substrs = ['stopped',
-                       'stop reason = breakpoint'])
+        self.runToBkpt("run")
+        # Evaluate ns1::value
+        self.expect("expression -- value", startstr = "(int) $0 = 100")
+
+        self.runToBkpt("continue")
+        # Evaluate ns2::value
+        self.expect("expression -- value", startstr = "(int) $1 = 200")
         
+        self.runToBkpt("continue")
         # On Mac OS X, gcc 4.2 emits the wrong debug info with respect to types.
         slist = ['(int) a = 12', 'anon_uint', 'a_uint', 'b_uint', 'y_uint']
         if self.platformIsDarwin() and self.getCompiler() in ['clang', 'llvm-gcc']:
             slist = ['(int) a = 12',
                      '::my_uint_t', 'anon_uint = 0',
                      '(A::uint_t) a_uint = 1',
                      '(A::B::uint_t) b_uint = 2',
                      '(Y::uint_t) y_uint = 3']
def test_with_run_command(self):
         self.expect("frame variable '(anonymous namespace)::i'", VARIABLES_DISPLAYED_CORRECTLY,
             startstr = '(int) (anonymous namespace)::i = 3',
             patterns = [' = 3'])
 
         # rdar://problem/8660275
         # test/namespace: 'expression -- i+j' not working
         # This has been fixed.
         self.expect("expression -- i + j",
-            startstr = "(int) $0 = 7")
-        # (int) $0 = 7
+            startstr = "(int) $2 = 7")
+        # (int) $2 = 7
 
         self.runCmd("expression -- i")
         self.runCmd("expression -- j")
 
         # rdar://problem/8668674
         # expression command with fully qualified namespace for a variable does not work
         self.expect("expression -- ::i", VARIABLES_DISPLAYED_CORRECTLY,
             patterns = [' = 3'])

packages/Python/lldbsuite/test/lang/cpp/namespace/main.cpp

 
 namespace A {
     namespace B {
         using namespace Y;
         int k;
     }
 }
 
+namespace ns1 {
+    int value = 100;
+}
+
+namespace ns2 {
+    int value = 200;
+}
+
 #include <stdio.h>
+void test_namespace_scopes() {
+    do {
+        using namespace ns1;
+        printf("ns1::value = %d\n", value); // Evaluate ns1::value
+    } while(0);
+    
+    do {
+        using namespace ns2;
+        printf("ns2::value = %d\n", value); // Evaluate ns2::value
+    } while(0);
+}
+
 int Foo::myfunc(int a)
 {
+    test_namespace_scopes();    
+
     ::my_uint_t anon_uint = 0;
     A::uint_t a_uint = 1;
     B::uint_t b_uint = 2;
     Y::uint_t y_uint = 3;
     i = 3;
     j = 4;
     printf("::i=%d\n", ::i);
     printf("A::B::j=%d\n", A::B::j);

source/Symbol/ClangASTContext.cpp

if (opaque_decl_ctx)
         SymbolFile *symbol_file = GetSymbolFile();
 
         for (clang::DeclContext *decl_context = root_decl_ctx; decl_context != nullptr && found_decls.empty(); decl_context = decl_context->getParent())
         {
             search_queue.insert(std::make_pair(decl_context, decl_context));
 
             for (auto it = search_queue.find(decl_context); it != search_queue.end(); it++)
             {
+                if (searched.find(it->second) != searched.end())
+                    continue;
                 searched.insert(it->second);
                 symbol_file->ParseDeclsForContext(CompilerDeclContext(this, it->second));
 
                 for (clang::Decl *child : it->second->decls())
                 {
                     if (clang::UsingDirectiveDecl *ud = llvm::dyn_cast<clang::UsingDirectiveDecl>(child))
                     {
                         clang::DeclContext *from = ud->getCommonAncestor();
                         if (searched.find(ud->getNominatedNamespace()) == searched.end())