[clang] Control analysis-based diagnostics with #pragma (PR #136323)

[Aaron Ballman via cfe-commits]

================
@@ -2504,23 +2505,37 @@ sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
       NumUninitAnalysisVariables(0), MaxUninitAnalysisVariablesPerFunction(0),
       NumUninitAnalysisBlockVisits(0),
       MaxUninitAnalysisBlockVisitsPerFunction(0) {
+}
+
+// We need this here for unique_ptr with forward declared class.
+sema::AnalysisBasedWarnings::~AnalysisBasedWarnings() = default;
 
+sema::AnalysisBasedWarnings::Policy
+sema::AnalysisBasedWarnings::getPolicyInEffectAt(SourceLocation Loc) {
   using namespace diag;
   DiagnosticsEngine &D = S.getDiagnostics();
+  Policy P;
 
-  DefaultPolicy.enableCheckUnreachable =
-      isEnabled(D, warn_unreachable) || isEnabled(D, warn_unreachable_break) ||
-      isEnabled(D, warn_unreachable_return) ||
-      isEnabled(D, warn_unreachable_loop_increment);
+  // Note: The enabled checks should be kept in sync with the switch in
+  // SemaPPCallbacks::PragmaDiagnostic().
+  P.enableCheckUnreachable =
+      PolicyOverrides.enableCheckUnreachable ||
+      isEnabled(D, Loc, warn_unreachable, warn_unreachable_break,
+                warn_unreachable_return, warn_unreachable_loop_increment);
 
-  DefaultPolicy.enableThreadSafetyAnalysis = isEnabled(D, warn_double_lock);
+  P.enableThreadSafetyAnalysis = PolicyOverrides.enableThreadSafetyAnalysis ||
+                                 isEnabled(D, Loc, warn_double_lock);
 
-  DefaultPolicy.enableConsumedAnalysis =
-      isEnabled(D, warn_use_in_invalid_state);
+  P.enableConsumedAnalysis = PolicyOverrides.enableConsumedAnalysis ||
+                             isEnabled(D, Loc, warn_use_in_invalid_state);
+  return P;
 }
 
-// We need this here for unique_ptr with forward declared class.
-sema::AnalysisBasedWarnings::~AnalysisBasedWarnings() = default;
+void sema::AnalysisBasedWarnings::clearOverrides() {
+  PolicyOverrides.enableCheckUnreachable = false;
----------------
AaronBallman wrote:

The overrides are set in `SemaPPCallback::PragmaDiagnostic()`, the others come from `AnalysisBasedWarnings::getPolicyInEffectAt()`

https://github.com/llvm/llvm-project/pull/136323