[lldb] s/FileSpec::Equal/FileSpec::Match

Summary:
The FileSpec class is often used as a sort of a pattern -- one specifies
a bare file name to search, and we check if in matches the full file
name of an existing module (for example).

These comparisons used FileSpec::Equal, which had some support for it
(via the full=false argument), but it was not a good fit for this job.

For one, it did a symmetric comparison, which makes sense for a function
called "equal", but not for typical searches (when searching for
"/foo/bar.so", we don't want to find a module whose name is just
"bar.so"). This resulted in patterns like:
    if (FileSpec::Equal(pattern, file, pattern.GetDirectory()))
which would request a "full" match only if the pattern really contained
a directory. This worked, but the intended behavior was very unobvious.

On top of that, a lot of the code wanted to handle the case of an
"empty" pattern, and treat it as matching everything. This resulted in
conditions like:
    if (pattern && !FileSpec::Equal(pattern, file, pattern.GetDirectory())
which are nearly impossible to decipher.

This patch introduces a FileSpec::Match function, which does exactly
what most of FileSpec::Equal callers want, an asymmetric match between a
"pattern" FileSpec and a an actual FileSpec. Empty paterns match
everything, filename-only patterns match only the filename component.

I've tried to update all callers of FileSpec::Equal to use a simpler
interface. Those that hardcoded full=true have been changed to use
operator==. Those passing full=pattern.GetDirectory() have been changed
to use FileSpec::Match.

There was also a handful of places which hardcoded full=false. I've
changed these to use FileSpec::Match too. This is a slight change in
semantics, but it does not look like that was ever intended, and it was
more likely a result of a misunderstanding of the "proper" way to use
FileSpec::Equal.

[In an ideal world a "FileSpec" and a "FileSpec pattern" would be two
different types, but given how widespread FileSpec is, it is unlikely
we'll get there in one go. This at least provides a good starting point
by centralizing all matching behavior.]

Reviewers: teemperor, JDevlieghere, jdoerfert

Subscribers: emaste, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D70851

2 files changed, 2 insertions, 5 deletions

diff --git a/lldb/source/Target/TargetList.cpp b/lldb/source/Target/TargetList.cpp
index ebd02a504d0..1b4db0c2aba 100644
--- a/lldb/source/Target/TargetList.cpp
+++ b/lldb/source/Target/TargetList.cpp
@@ -457,15 +457,12 @@ TargetSP TargetList::FindTargetWithExecutableAndArchitecture(
     const FileSpec &exe_file_spec, const ArchSpec *exe_arch_ptr) const {
   std::lock_guard<std::recursive_mutex> guard(m_target_list_mutex);
   TargetSP target_sp;
-  bool full_match = (bool)exe_file_spec.GetDirectory();
-
   collection::const_iterator pos, end = m_target_list.end();
   for (pos = m_target_list.begin(); pos != end; ++pos) {
     Module *exe_module = (*pos)->GetExecutableModulePointer();
 
     if (exe_module) {
-      if (FileSpec::Equal(exe_file_spec, exe_module->GetFileSpec(),
-                          full_match)) {
+      if (FileSpec::Match(exe_file_spec, exe_module->GetFileSpec())) {
         if (exe_arch_ptr) {
           if (!exe_arch_ptr->IsCompatibleMatch(exe_module->GetArchitecture()))
             continue;
diff --git a/lldb/source/Target/ThreadPlanStepInRange.cpp b/lldb/source/Target/ThreadPlanStepInRange.cpp
index 77772aed516..fdb2782bc51 100644
--- a/lldb/source/Target/ThreadPlanStepInRange.cpp
+++ b/lldb/source/Target/ThreadPlanStepInRange.cpp
@@ -339,7 +339,7 @@ bool ThreadPlanStepInRange::FrameMatchesAvoidCriteria() {
     if (frame_library) {
       for (size_t i = 0; i < num_libraries; i++) {
         const FileSpec &file_spec(libraries_to_avoid.GetFileSpecAtIndex(i));
-        if (FileSpec::Equal(file_spec, frame_library, false)) {
+        if (FileSpec::Match(file_spec, frame_library)) {
           libraries_say_avoid = true;
           break;
         }