[analyzer] Remove deprecated option VirtualCall:PureOnly (#131823)

VirtualCallChecker.cpp implements two related checkers:
- `optin.cplusplus.VirtualCall` which reports situations when
constructors or destructors call virtual methods (which is bugprone
because it does not trigger virtual dispatch, but can be legitmate).
- `cplusplus.PureVirtualCall` reports situations when constructors or
destructors call _pure_ virtual methods, which is an error.

Six years ago these two bug types were both reported by the same checker
(called `optin.cplusplus.VirtualCall`) and it had an option called
`PureOnly` which limited its output to the pure case.

When (in 2019) the two checker parts were separated by the commit
d3971fe97b64785c079d64bf4c8c3e2b5e1f85a1, the option `PureOnly` was
preserved for the sake of compatibility, but it is no longer useful
(when it is set to true, it just suppresses all reports from
`optin.cplusplus.VirtualCall`) so it was marked as deprecated.

I'm removing this deprecated option now because it is no longer relevant
and its presence caused minor complications when I was porting
`VirtualCallChecker.cpp` to the new multipart checker framework
(introduced in 27099982da2f5a6c2d282d6b385e79d080669546).

clang/docs/ReleaseNotes.rst

@@ -491,6 +491,11 @@ Crash and bug fixes
 Improvements
 ^^^^^^^^^^^^
 
+- The checker option ``optin.cplusplus.VirtualCall:PureOnly`` was removed,
+  because it had been deprecated since 2019 and it is completely useless (it
+  was kept only for compatibility with pre-2019 versions, setting it to true is
+  equivalent to completely disabling the checker).
+
 Moved checkers
 ^^^^^^^^^^^^^^
 

clang/include/clang/StaticAnalyzer/Checkers/Checkers.td

@@ -750,22 +750,12 @@ def UninitializedObjectChecker: Checker<"UninitializedObject">,
   ]>,
   Documentation<HasDocumentation>;
 
-def VirtualCallChecker : Checker<"VirtualCall">,
+def VirtualCallChecker
+    : Checker<"VirtualCall">,
       HelpText<"Check virtual function calls during construction/destruction">,
-  CheckerOptions<[
-    CmdLineOption<Boolean,
-                  "ShowFixIts",
+      CheckerOptions<[CmdLineOption<Boolean, "ShowFixIts",
                                     "Enable fix-it hints for this checker",
-                  "false",
-                  InAlpha>,
-    CmdLineOption<Boolean,
-                  "PureOnly",
-                  "Disables the checker. Keeps cplusplus.PureVirtualCall "
-                  "enabled. This option is only provided for backwards "
-                  "compatibility.",
-                  "false",
-                  InAlpha>
-  ]>,
+                                    "false", InAlpha>]>,
       Dependencies<[VirtualCallModeling]>,
       Documentation<HasDocumentation>;
 

clang/lib/StaticAnalyzer/Checkers/VirtualCallChecker.cpp

@@ -214,14 +214,11 @@ void ento::registerPureVirtualCallChecker(CheckerManager &Mgr) {
 
 void ento::registerVirtualCallChecker(CheckerManager &Mgr) {
   auto *Chk = Mgr.getChecker<VirtualCallChecker>();
-  if (!Mgr.getAnalyzerOptions().getCheckerBooleanOption(
-          Mgr.getCurrentCheckerName(), "PureOnly")) {
   Chk->BT_Impure = std::make_unique<BugType>(
       Mgr.getCurrentCheckerName(), "Unexpected loss of virtual dispatch",
       categories::CXXObjectLifecycle);
   Chk->ShowFixIts = Mgr.getAnalyzerOptions().getCheckerBooleanOption(
       Mgr.getCurrentCheckerName(), "ShowFixIts");
-  }
 }
 
 bool ento::shouldRegisterVirtualCallModeling(const CheckerManager &mgr) {

clang/test/Analysis/analyzer-config.c

@@ -108,7 +108,6 @@
 // CHECK-NEXT: optin.cplusplus.UninitializedObject:IgnoreRecordsWithField = ""
 // CHECK-NEXT: optin.cplusplus.UninitializedObject:NotesAsWarnings = false
 // CHECK-NEXT: optin.cplusplus.UninitializedObject:Pedantic = false
-// CHECK-NEXT: optin.cplusplus.VirtualCall:PureOnly = false
 // CHECK-NEXT: optin.cplusplus.VirtualCall:ShowFixIts = false
 // CHECK-NEXT: optin.osx.cocoa.localizability.NonLocalizedStringChecker:AggressiveReport = false
 // CHECK-NEXT: optin.performance.Padding:AllowedPad = 24

clang/test/Analysis/virtualcall.cpp

@@ -6,29 +6,11 @@
 // RUN:                    -analyzer-checker=debug.ExprInspection \
 // RUN:                    -std=c++11 -verify=pure -std=c++11 %s
 
-// RUN: %clang_analyze_cc1 -analyzer-checker=core,optin.cplusplus.VirtualCall \
-// RUN:                    -analyzer-config \
-// RUN:                        optin.cplusplus.VirtualCall:PureOnly=true \
-// RUN:                    -analyzer-checker=debug.ExprInspection \
-// RUN:                    -std=c++11 -verify=none %s
-
 // RUN: %clang_analyze_cc1 -analyzer-checker=core,cplusplus.PureVirtualCall \
 // RUN:                    -analyzer-checker=optin.cplusplus.VirtualCall \
 // RUN:                    -analyzer-checker=debug.ExprInspection \
 // RUN:                    -std=c++11 -verify=pure,impure -std=c++11 %s
 
-// RUN: %clang_analyze_cc1 -analyzer-checker=core,cplusplus.PureVirtualCall \
-// RUN:                    -analyzer-checker=optin.cplusplus.VirtualCall \
-// RUN:                    -analyzer-config \
-// RUN:                        optin.cplusplus.VirtualCall:PureOnly=true \
-// RUN:                    -analyzer-checker=debug.ExprInspection \
-// RUN:                    -std=c++11 -verify=pure %s
-
-
-// We expect no diagnostics when all checks are disabled.
-// none-no-diagnostics
-
-
 #include "virtualcall.h"
 
 void clang_analyzer_warnIfReached();