[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

1 files changed, 6 insertions, 14 deletions

diff --git a/lldb/source/Core/Module.cpp b/lldb/source/Core/Module.cpp
index a8a92bb5b1f..cc4eea67417 100644
--- a/lldb/source/Core/Module.cpp
+++ b/lldb/source/Core/Module.cpp
@@ -613,12 +613,10 @@ void Module::FindCompileUnits(const FileSpec &path,
   const size_t num_compile_units = GetNumCompileUnits();
   SymbolContext sc;
   sc.module_sp = shared_from_this();
-  const bool compare_directory = (bool)path.GetDirectory();
   for (size_t i = 0; i < num_compile_units; ++i) {
     sc.comp_unit = GetCompileUnitAtIndex(i).get();
     if (sc.comp_unit) {
-      if (FileSpec::Equal(sc.comp_unit->GetPrimaryFile(), path,
-                          compare_directory))
+      if (FileSpec::Match(path, sc.comp_unit->GetPrimaryFile()))
         sc_list.Append(sc);
     }
   }
@@ -1561,19 +1559,13 @@ bool Module::MatchesModuleSpec(const ModuleSpec &module_ref) {
   }
 
   const FileSpec &file_spec = module_ref.GetFileSpec();
-  if (file_spec) {
-    if (!FileSpec::Equal(file_spec, m_file, (bool)file_spec.GetDirectory()) &&
-        !FileSpec::Equal(file_spec, m_platform_file,
-                         (bool)file_spec.GetDirectory()))
-      return false;
-  }
+  if (!FileSpec::Match(file_spec, m_file) &&
+      !FileSpec::Match(file_spec, m_platform_file))
+    return false;
 
   const FileSpec &platform_file_spec = module_ref.GetPlatformFileSpec();
-  if (platform_file_spec) {
-    if (!FileSpec::Equal(platform_file_spec, GetPlatformFileSpec(),
-                         (bool)platform_file_spec.GetDirectory()))
-      return false;
-  }
+  if (!FileSpec::Match(platform_file_spec, GetPlatformFileSpec()))
+    return false;
 
   const ArchSpec &arch = module_ref.GetArchitecture();
   if (arch.IsValid()) {