[lldb] Turn lldb_private::Status into a value type. (#106163)

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

`    ResultTy DoFoo(Status& error)
`
to

`    llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

1 files changed, 15 insertions, 13 deletions

diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
index 59fc872..92fd2fc 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -1050,10 +1050,10 @@ Status NativeProcessLinux::Resume(const ResumeActionList &resume_actions) {
       Status error = ResumeThread(static_cast<NativeThreadLinux &>(*thread),
                                   action->state, signo);
       if (error.Fail())
-        return Status("NativeProcessLinux::%s: failed to resume thread "
-                      "for pid %" PRIu64 ", tid %" PRIu64 ", error = %s",
-                      __FUNCTION__, GetID(), thread->GetID(),
-                      error.AsCString());
+        return Status::FromErrorStringWithFormat(
+            "NativeProcessLinux::%s: failed to resume thread "
+            "for pid %" PRIu64 ", tid %" PRIu64 ", error = %s",
+            __FUNCTION__, GetID(), thread->GetID(), error.AsCString());
 
       break;
     }
@@ -1063,10 +1063,11 @@ Status NativeProcessLinux::Resume(const ResumeActionList &resume_actions) {
       break;
 
     default:
-      return Status("NativeProcessLinux::%s (): unexpected state %s specified "
-                    "for pid %" PRIu64 ", tid %" PRIu64,
-                    __FUNCTION__, StateAsCString(action->state), GetID(),
-                    thread->GetID());
+      return Status::FromErrorStringWithFormat(
+          "NativeProcessLinux::%s (): unexpected state %s specified "
+          "for pid %" PRIu64 ", tid %" PRIu64,
+          __FUNCTION__, StateAsCString(action->state), GetID(),
+          thread->GetID());
     }
   }
 
@@ -1209,7 +1210,7 @@ Status NativeProcessLinux::GetMemoryRegionInfo(lldb::addr_t load_addr,
 
   if (m_supports_mem_region == LazyBool::eLazyBoolNo) {
     // We're done.
-    return Status("unsupported");
+    return Status::FromErrorString("unsupported");
   }
 
   Status error = PopulateMemoryRegionCache();
@@ -1318,7 +1319,7 @@ Status NativeProcessLinux::PopulateMemoryRegionCache() {
     LLDB_LOG(log,
              "failed to find any procfs maps entries, assuming no support "
              "for memory region metadata retrieval");
-    return Status("not supported");
+    return Status::FromErrorString("not supported");
   }
 
   LLDB_LOG(log, "read {0} memory region entries from /proc/{1}/maps",
@@ -1853,8 +1854,9 @@ Status NativeProcessLinux::GetLoadedModuleFileSpec(const char *module_path,
       return Status();
     }
   }
-  return Status("Module file (%s) not found in /proc/%" PRIu64 "/maps file!",
-                module_file_spec.GetFilename().AsCString(), GetID());
+  return Status::FromErrorStringWithFormat(
+      "Module file (%s) not found in /proc/%" PRIu64 "/maps file!",
+      module_file_spec.GetFilename().AsCString(), GetID());
 }
 
 Status NativeProcessLinux::GetFileLoadAddress(const llvm::StringRef &file_name,
@@ -1871,7 +1873,7 @@ Status NativeProcessLinux::GetFileLoadAddress(const llvm::StringRef &file_name,
       return Status();
     }
   }
-  return Status("No load address found for specified file.");
+  return Status::FromErrorString("No load address found for specified file.");
 }
 
 NativeThreadLinux *NativeProcessLinux::GetThreadByID(lldb::tid_t tid) {