[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, 3 insertions, 8 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 837a475c166..b8575d13d45 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -1950,9 +1950,8 @@ uint32_t SymbolFileDWARF::ResolveSymbolContext(const FileSpec &file_spec,
       if (!dc_cu)
         continue;
 
-      const bool full_match = (bool)file_spec.GetDirectory();
       bool file_spec_matches_cu_file_spec =
-          FileSpec::Equal(file_spec, dc_cu->GetPrimaryFile(), full_match);
+          FileSpec::Match(file_spec, dc_cu->GetPrimaryFile());
       if (check_inlines || file_spec_matches_cu_file_spec) {
         SymbolContext sc(m_objfile_sp->GetModule());
         sc.comp_unit = dc_cu;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index d3090ed3b6f..cce666a222d 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -812,12 +812,8 @@ uint32_t SymbolFileDWARFDebugMap::ResolveSymbolContext(
 
     if (!resolve) {
       FileSpec so_file_spec;
-      if (GetFileSpecForSO(i, so_file_spec)) {
-        // Match the full path if the incoming file_spec has a directory (not
-        // just a basename)
-        const bool full_match = (bool)file_spec.GetDirectory();
-        resolve = FileSpec::Equal(file_spec, so_file_spec, full_match);
-      }
+      if (GetFileSpecForSO(i, so_file_spec))
+        resolve = FileSpec::Match(file_spec, so_file_spec);
     }
     if (resolve) {
       SymbolFileDWARF *oso_dwarf = GetSymbolFileByOSOIndex(i);