[PCH] Fix reading from PCH of diagnostic pragmas.

In certain cases ASTReader would call the normal DiagnosticsEngine API to initialize
the state of diagnostic pragmas but DiagnosticsEngine would try to compare source locations
leading to crash because the main FileID was not yet initialized.

Yet another case of the ASTReader trying to use the normal APIs and inadvertently breaking
invariants. Fix this by having the ASTReader set up the internal state directly.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144153 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/Diagnostic.h

@@ -624,6 +624,21 @@ private:
   /// to insert, remove, or modify at a particular position.
   FixItHint FixItHints[MaxFixItHints];
 
+  DiagnosticMappingInfo makeMappingInfo(diag::Mapping Map, SourceLocation L) {
+    bool isPragma = L.isValid();
+    DiagnosticMappingInfo MappingInfo = DiagnosticMappingInfo::Make(
+      Map, /*IsUser=*/true, isPragma);
+
+    // If this is a pragma mapping, then set the diagnostic mapping flags so
+    // that we override command line options.
+    if (isPragma) {
+      MappingInfo.setNoWarningAsError(true);
+      MappingInfo.setNoErrorAsFatal(true);
+    }
+
+    return MappingInfo;
+  }
+
   /// ProcessDiag - This is the method used to report a diagnostic that is
   /// finally fully formed.
   ///

lib/Basic/Diagnostic.cpp

@@ -169,18 +169,9 @@ void DiagnosticsEngine::setDiagnosticMapping(diag::kind Diag, diag::Mapping Map,
          "Cannot map errors into warnings!");
   assert(!DiagStatePoints.empty());
 
-  bool isPragma = L.isValid();
   FullSourceLoc Loc(L, *SourceMgr);
   FullSourceLoc LastStateChangePos = DiagStatePoints.back().Loc;
-  DiagnosticMappingInfo MappingInfo = DiagnosticMappingInfo::Make(
-    Map, /*IsUser=*/true, isPragma);
-
-  // If this is a pragma mapping, then set the diagnostic mapping flags so that
-  // we override command line options.
-  if (isPragma) {
-    MappingInfo.setNoWarningAsError(true);
-    MappingInfo.setNoErrorAsFatal(true);
-  }
+  DiagnosticMappingInfo MappingInfo = makeMappingInfo(Map, L);
 
   // Common case; setting all the diagnostics of a group in one place.
   if (Loc.isInvalid() || Loc == LastStateChangePos) {

lib/Serialization/ASTReader.cpp

@@ -3109,6 +3109,10 @@ void ASTReader::ReadPragmaDiagnosticMappings(DiagnosticsEngine &Diag) {
     unsigned Idx = 0;
     while (Idx < F.PragmaDiagMappings.size()) {
       SourceLocation Loc = ReadSourceLocation(F, F.PragmaDiagMappings[Idx++]);
+      Diag.DiagStates.push_back(*Diag.GetCurDiagState());
+      Diag.DiagStatePoints.push_back(
+          DiagnosticsEngine::DiagStatePoint(&Diag.DiagStates.back(),
+                                            FullSourceLoc(Loc, SourceMgr)));
       while (1) {
         assert(Idx < F.PragmaDiagMappings.size() &&
                "Invalid data, didn't find '-1' marking end of diag/map pairs");
@@ -3121,8 +3125,8 @@ void ASTReader::ReadPragmaDiagnosticMappings(DiagnosticsEngine &Diag) {
           break; // no more diag/map pairs for this location.
         }
         diag::Mapping Map = (diag::Mapping)F.PragmaDiagMappings[Idx++];
-        // The user bit gets set by WritePragmaDiagnosticMappings.
-        Diag.setDiagnosticMapping(DiagID, Map, Loc);
+        DiagnosticMappingInfo MappingInfo = Diag.makeMappingInfo(Map, Loc);
+        Diag.GetCurDiagState()->setMappingInfo(DiagID, MappingInfo);
       }
     }
   }

test/Index/Inputs/pragma_disable_warning.h

@@ -0,0 +1 @@
+#pragma clang diagnostic ignored "-Wunused-parameter"

test/Index/pragma-diag-reparse.c

@@ -1,4 +1,5 @@
 #pragma clang diagnostic ignored "-Wtautological-compare"
+#include "pragma_disable_warning.h"
 
 int main (int argc, const char * argv[])
 {
@@ -13,6 +14,7 @@ int main (int argc, const char * argv[])
 void foo() { int b=0; while (b==b); }
 
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_FAILONERROR=1 c-index-test -test-load-source-reparse 5 local \
+// RUN: -I%S/Inputs \
 // RUN:   %s -Wall -Werror | FileCheck %s
 
-// CHECK: pragma-diag-reparse.c:7:7: VarDecl=x:7:7 (Definition) Extent=[7:3 - 7:10]
+// CHECK: pragma-diag-reparse.c:8:7: VarDecl=x:8:7 (Definition) Extent=[8:3 - 8:10]