From d0abc5054daa533f3031e08eccd959a70b75551e Mon Sep 17 00:00:00 2001
From: Richard Trieu <rtrieu@google.com>
Date: Tue, 15 Apr 2014 00:57:50 +0000
Subject: [PATCH] Fix a bad interaction between -Wtautological-overlap-compare
 and delayed diagnostics which caused delayed diagnostics on dead paths to be
 emitted.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206232 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/AnalysisDeclContext.cpp |  6 ++++++
 lib/Sema/AnalysisBasedWarnings.cpp   | 15 +++++++++++----
 test/Sema/warn-overlap.c             |  6 ++++++
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/lib/Analysis/AnalysisDeclContext.cpp b/lib/Analysis/AnalysisDeclContext.cpp
index c90d947951..ef9ce56c9b 100644
--- a/lib/Analysis/AnalysisDeclContext.cpp
+++ b/lib/Analysis/AnalysisDeclContext.cpp
@@ -189,6 +189,9 @@ CFG *AnalysisDeclContext::getCFG() {
 
     if (PM)
       addParentsForSyntheticStmts(cfg.get(), *PM);
+
+    // The Obersver should only observe one build of the CFG.
+    getCFGBuildOptions().Observer = 0;
   }
   return cfg.get();
 }
@@ -205,6 +208,9 @@ CFG *AnalysisDeclContext::getUnoptimizedCFG() {
 
     if (PM)
       addParentsForSyntheticStmts(completeCFG.get(), *PM);
+
+    // The Obersver should only observe one build of the CFG.
+    getCFGBuildOptions().Observer = 0;
   }
   return completeCFG.get();
 }
diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index 32bdef6da9..fc591bd77c 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -1838,12 +1838,12 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
       .setAlwaysAdd(Stmt::AttributedStmtClass);
   }
 
+  // Install the logical handler for -Wtautological-overlap-compare
+  std::unique_ptr<LogicalErrorHandler> LEH;
   if (Diags.getDiagnosticLevel(diag::warn_tautological_overlap_comparison,
                                D->getLocStart())) {
-    LogicalErrorHandler LEH(S);
-    AC.getCFGBuildOptions().Observer = &LEH;
-    AC.getCFG();
-    AC.getCFGBuildOptions().Observer = 0;
+    LEH.reset(new LogicalErrorHandler(S));
+    AC.getCFGBuildOptions().Observer = LEH.get();
   }
 
   // Emit delayed diagnostics.
@@ -1991,6 +1991,13 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
     }
   }
 
+  // If none of the previous checks caused a CFG build, trigger one here
+  // for -Wtautological-overlap-compare
+  if (Diags.getDiagnosticLevel(diag::warn_tautological_overlap_comparison,
+                               D->getLocStart())) {
+    AC.getCFG();
+  }
+
   // Collect statistics about the CFG if it was built.
   if (S.CollectStats && AC.isCFGBuilt()) {
     ++NumFunctionsAnalyzed;
diff --git a/test/Sema/warn-overlap.c b/test/Sema/warn-overlap.c
index c98547153c..44d6ad5efa 100644
--- a/test/Sema/warn-overlap.c
+++ b/test/Sema/warn-overlap.c
@@ -56,3 +56,9 @@ void f(int x) {
   if (x == (mydefine + 1) && x > 3) { }
 }
 
+// Don't generate a warning here.
+void array_out_of_bounds() {
+  int x;
+  int buffer[4];
+  x = (-7 > 0) ? (buffer[-7]) : 0;
+}
-- 
2.40.0