Fix DWARF handling of inlined functions in namespaces

Currently an inlined function in a namespace in DWARF will
be given a name comprised of just `namespace::`. This is due
to a logic error in ComputeQualifiedName, where it doesn't
handle an empty `unqualified_name` properly.

We apparently have a fair number of these in our Mac builds,
an example of the DWARF that's being mishandled looks like:
0x117eda40:     TAG_namespace [5] *
                 AT_name( "js" )
                 AT_decl_file( "../../dist/include/js/Utility.h" )
                 AT_decl_line( 35 )

0x11808500:         TAG_subprogram [251] *
                     AT_low_pc( 0x0000000002f12110 )
                     AT_high_pc( 0x0000000002f1216b )
                     AT_APPLE_omit_frame_ptr( 0x01 )
                     AT_frame_base( rsp )
                     AT_abstract_origin( {0x0000000011800a4f}"_ZN2js40TraceManuallyBarrieredGenericPointerEdgeEP8JSTracerPPNS_2gc4CellEPKc" )
                      AT_MIPS_linkage_name( "_ZN2js40TraceManuallyBarrieredGenericPointerEdgeEP8JSTracerPPNS_2gc4CellEPKc" )
                      AT_name( "TraceManuallyBarrieredGenericPointerEdge" )
                      AT_decl_file( "/builds/slave/rel-m-rel-m64_bld-000000000000/build/js/src/gc/Marking.cpp" )
                      AT_decl_line( 547 )
                      AT_external( 0x01 )
                      AT_APPLE_optimized( 0x01 )
                      AT_inline( DW_INL_inlined )

This turned a few instances of this in the file I was testing on into
`<name omitted>`, which seems to just be a symptom of the
"DW_AT_abstract_origin comes later in the file" issue. (Which is probably
also worth fixing given that it occurs some 29k times when dumping
symbols from Firefox's XUL binary, but it's a separate issue.)

R=mark@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1887033002 .

src/common/dwarf_cu_to_module.cc

@@ -384,17 +384,17 @@ string DwarfCUToModule::GenericDIEHandler::ComputeQualifiedName() {
     qualified_name = &specification_->qualified_name;
   }
 
-  const string *unqualified_name;
+  const string *unqualified_name = NULL;
   const string *enclosing_name;
   if (!qualified_name) {
-    // Find our unqualified name. If the DIE has its own DW_AT_name
+    // Find the unqualified name. If the DIE has its own DW_AT_name
-    // attribute, then use that; otherwise, check our specification.
+    // attribute, then use that; otherwise, check the specification.
-    if (name_attribute_.empty() && specification_)
+    if (!name_attribute_.empty())
-      unqualified_name = &specification_->unqualified_name;
-    else
       unqualified_name = &name_attribute_;
+    else if (specification_)
+      unqualified_name = &specification_->unqualified_name;
 
-    // Find the name of our enclosing context. If we have a
+    // Find the name of the enclosing context. If this DIE has a
     // specification, it's the specification's enclosing context that
     // counts; otherwise, use this DIE's context.
     if (specification_)
@@ -408,7 +408,7 @@ string DwarfCUToModule::GenericDIEHandler::ComputeQualifiedName() {
   string return_value;
   if (qualified_name) {
     return_value = *qualified_name;
-  } else {
+  } else if (unqualified_name && enclosing_name) {
     // Combine the enclosing name and unqualified name to produce our
     // own fully-qualified name.
     return_value = cu_context_->language->MakeQualifiedName(*enclosing_name,
@@ -417,7 +417,7 @@ string DwarfCUToModule::GenericDIEHandler::ComputeQualifiedName() {
 
   // If this DIE was marked as a declaration, record its names in the
   // specification table.
-  if (declaration_) {
+  if (declaration_ && qualified_name || (unqualified_name && enclosing_name)) {
     Specification spec;
     if (qualified_name) {
       spec.qualified_name = *qualified_name;

src/common/dwarf_cu_to_module_unittest.cc

@@ -1323,6 +1323,29 @@ TEST_F(Specifications, InlineFunction) {
                0x1758a0f941b71efbULL, 0x1cf154f1f545e146ULL);
 }
 
+// An inline function in a namespace should correctly derive its
+// name from its abstract origin, and not just the namespace name.
+TEST_F(Specifications, InlineFunctionInNamespace) {
+  PushLine(0x1758a0f941b71efbULL, 0x1cf154f1f545e146ULL, "line-file", 75173118);
+
+  StartCU();
+  DIEHandler* space_handler
+      = StartNamedDIE(&root_handler_, dwarf2reader::DW_TAG_namespace,
+                      "Namespace");
+  ASSERT_TRUE(space_handler != NULL);
+  AbstractInstanceDIE(space_handler, 0x1e8dac5d507ed7abULL,
+                      dwarf2reader::DW_INL_inlined, 0LL, "func-name");
+  DefineInlineInstanceDIE(space_handler, "", 0x1e8dac5d507ed7abULL,
+                       0x1758a0f941b71efbULL, 0x1cf154f1f545e146ULL);
+  space_handler->Finish();
+  delete space_handler;
+  root_handler_.Finish();
+
+  TestFunctionCount(1);
+  TestFunction(0, "Namespace::func-name",
+               0x1758a0f941b71efbULL, 0x1cf154f1f545e146ULL);
+}
+
 // Check name construction for a long chain containing each combination of:
 // - struct, union, class, namespace
 // - direct and definition