[lldb] Make frame var --regex always search globals

Currently frame var --regex sometimes searches globals, sometimes it doesn't.
This happens because `StackFrame::GetVariableList` always returns the biggest
list it has, regardless of whether only globals were requested or not. In other
words, if a previous call to `GetVariableList` requested globals, all subsequent
calls will see them.

The implication here is that users of `StackFrame::GetVariableList` are expected
to filter the results of this function. This is what we do for a vanilla
`frame var` command. But it is not what we do when `--regex` is used. This
commit solves the issue by:

1. Making `--regex` imply `--globals`. This matches the behavior of `frame var
<some_name>`, which will also search the global scope.
2. Making the `--regex` search respect the command object options.

See the added test for an example of the oddities this patch addresses. Without
the patch, the test fails. However it could be made to pass by calling a plain
`frame var` before calling `frame var --regex A::`.

Differential Revision: https://reviews.llvm.org/D155334

1 files changed, 56 insertions, 36 deletions

diff --git a/lldb/source/Commands/CommandObjectFrame.cpp b/lldb/source/Commands/CommandObjectFrame.cpp
index 7638076..1390fd8 100644
--- a/lldb/source/Commands/CommandObjectFrame.cpp
+++ b/lldb/source/Commands/CommandObjectFrame.cpp
@@ -499,6 +499,31 @@ protected:
     }
   }
 
+  /// Finds all the variables in `all_variables` whose name matches `regex`,
+  /// inserting them into `matches`. Variables already contained in `matches`
+  /// are not inserted again.
+  /// Nullopt is returned in case of no matches.
+  /// A sub-range of `matches` with all newly inserted variables is returned.
+  /// This may be empty if all matches were already contained in `matches`.
+  std::optional<llvm::ArrayRef<VariableSP>>
+  findUniqueRegexMatches(RegularExpression &regex,
+                         VariableList &matches,
+                         const VariableList &all_variables) {
+    bool any_matches = false;
+    const size_t previous_num_vars = matches.GetSize();
+
+    for (const VariableSP &var : all_variables) {
+      if (!var->NameMatches(regex) || !ScopeRequested(var->GetScope()))
+        continue;
+      any_matches = true;
+      matches.AddVariableIfUnique(var);
+    }
+
+    if (any_matches)
+      return matches.toArrayRef().drop_front(previous_num_vars);
+    return std::nullopt;
+  }
+
   bool DoExecute(Args &command, CommandReturnObject &result) override {
     // No need to check "frame" for validity as eCommandRequiresFrame ensures
     // it is valid
@@ -506,6 +531,10 @@ protected:
 
     Stream &s = result.GetOutputStream();
 
+    // Using a regex should behave like looking for an exact name match: it
+    // also finds globals.
+    m_option_variable.show_globals |= m_option_variable.use_regex;
+
     // Be careful about the stack frame, if any summary formatter runs code, it
     // might clear the StackFrameList for the thread.  So hold onto a shared
     // pointer to the frame so it stays alive.
@@ -518,7 +547,6 @@ protected:
       result.AppendError(error.AsCString());
 
     }
-    VariableSP var_sp;
     ValueObjectSP valobj_sp;
 
     TypeSummaryImplSP summary_format_sp;
@@ -551,46 +579,38 @@ protected:
         // objects from them...
         for (auto &entry : command) {
           if (m_option_variable.use_regex) {
-            const size_t regex_start_index = regex_var_list.GetSize();
             llvm::StringRef name_str = entry.ref();
             RegularExpression regex(name_str);
             if (regex.IsValid()) {
-              size_t num_matches = 0;
-              const size_t num_new_regex_vars =
-                  variable_list->AppendVariablesIfUnique(regex, regex_var_list,
-                                                         num_matches);
-              if (num_new_regex_vars > 0) {
-                for (size_t regex_idx = regex_start_index,
-                            end_index = regex_var_list.GetSize();
-                     regex_idx < end_index; ++regex_idx) {
-                  var_sp = regex_var_list.GetVariableAtIndex(regex_idx);
-                  if (var_sp) {
-                    valobj_sp = frame->GetValueObjectForFrameVariable(
-                        var_sp, m_varobj_options.use_dynamic);
-                    if (valobj_sp) {
-                      std::string scope_string;
-                      if (m_option_variable.show_scope)
-                        scope_string = GetScopeString(var_sp).str();
-
-                      if (!scope_string.empty())
-                        s.PutCString(scope_string);
-
-                      if (m_option_variable.show_decl &&
-                          var_sp->GetDeclaration().GetFile()) {
-                        bool show_fullpaths = false;
-                        bool show_module = true;
-                        if (var_sp->DumpDeclaration(&s, show_fullpaths,
-                                                    show_module))
-                          s.PutCString(": ");
-                      }
-                      valobj_sp->Dump(result.GetOutputStream(), options);
-                    }
-                  }
-                }
-              } else if (num_matches == 0) {
+              std::optional<llvm::ArrayRef<VariableSP>> results =
+                  findUniqueRegexMatches(regex, regex_var_list, *variable_list);
+              if (!results) {
                 result.AppendErrorWithFormat(
                     "no variables matched the regular expression '%s'.",
                     entry.c_str());
+                continue;
+              }
+              for (const VariableSP &var_sp : *results) {
+                valobj_sp = frame->GetValueObjectForFrameVariable(
+                    var_sp, m_varobj_options.use_dynamic);
+                if (valobj_sp) {
+                  std::string scope_string;
+                  if (m_option_variable.show_scope)
+                    scope_string = GetScopeString(var_sp).str();
+
+                  if (!scope_string.empty())
+                    s.PutCString(scope_string);
+
+                  if (m_option_variable.show_decl &&
+                      var_sp->GetDeclaration().GetFile()) {
+                    bool show_fullpaths = false;
+                    bool show_module = true;
+                    if (var_sp->DumpDeclaration(&s, show_fullpaths,
+                                                show_module))
+                      s.PutCString(": ");
+                  }
+                  valobj_sp->Dump(result.GetOutputStream(), options);
+                }
               }
             } else {
               if (llvm::Error err = regex.GetError())
@@ -648,7 +668,7 @@ protected:
         const size_t num_variables = variable_list->GetSize();
         if (num_variables > 0) {
           for (size_t i = 0; i < num_variables; i++) {
-            var_sp = variable_list->GetVariableAtIndex(i);
+            VariableSP var_sp = variable_list->GetVariableAtIndex(i);
             if (!ScopeRequested(var_sp->GetScope()))
                 continue;
             std::string scope_string;