Optionally demote fatal errors to non-fatal errors.

This behavior is enabled when the new CXTranslationUnit_KeepGoing
option is passed to clang_parseTranslationUnit{,2}. It is geared
towards use by IDEs and similar consumers of the clang-c API where
fatal errors may arise when parsing incomplete code mid-edit, or
when include paths are not properly configured yet. In such situations
one still wants to get as much information as possible about a TU.
Previously, the semantic analysis would not instantiate templates
or report additional fatal errors after the first fatal error was
encountered.

Fixes PR24268.

Patch by Milian Wolff.

llvm-svn: 262318

clang/include/clang-c/Index.h

@@ -1208,7 +1208,18 @@ enum CXTranslationUnit_Flags {
    * trades runtime on the first parse (serializing the preamble takes time) for
    * reduced runtime on the second parse (can now reuse the preamble).
    */
-  CXTranslationUnit_CreatePreambleOnFirstParse = 0x100
+  CXTranslationUnit_CreatePreambleOnFirstParse = 0x100,
+
+  /**
+   * \brief Do not stop processing when fatal errors are encountered.
+   *
+   * When fatal errors are encountered while parsing a translation unit,
+   * semantic analysis is typically stopped early when compiling code. A common
+   * source for fatal errors are unresolvable include files. For the
+   * purposes of an IDE, this is undesirable behavior and as much information
+   * as possible should be reported. Use this flag to enable this behavior.
+   */
+  CXTranslationUnit_KeepGoing = 0x200
 };
 
 /**

clang/include/clang/Basic/Diagnostic.h

@@ -173,6 +173,7 @@ private:
   bool WarningsAsErrors;         // Treat warnings like errors.
   bool EnableAllWarnings;        // Enable all warnings.
   bool ErrorsAsFatal;            // Treat errors like fatal errors.
+  bool FatalsAsError;             // Treat fatal errors like errors.
   bool SuppressSystemWarnings;   // Suppress warnings in system headers.
   bool SuppressAllDiagnostics;   // Suppress all diagnostics.
   bool ElideType;                // Elide common types of templates.
@@ -455,6 +456,12 @@ public:
   void setErrorsAsFatal(bool Val) { ErrorsAsFatal = Val; }
   bool getErrorsAsFatal() const { return ErrorsAsFatal; }
 
+  /// \brief When set to true, any fatal error reported is made an error.
+  ///
+  /// This setting takes precedence over the setErrorsAsFatal setting above.
+  void setFatalsAsError(bool Val) { FatalsAsError = Val; }
+  bool getFatalsAsError() const { return FatalsAsError; }
+
   /// \brief When set to true mask warnings that come from system headers.
   void setSuppressSystemWarnings(bool Val) { SuppressSystemWarnings = Val; }
   bool getSuppressSystemWarnings() const { return SuppressSystemWarnings; }

clang/lib/Basic/Diagnostic.cpp

@@ -68,6 +68,7 @@ DiagnosticsEngine::DiagnosticsEngine(
   WarningsAsErrors = false;
   EnableAllWarnings = false;
   ErrorsAsFatal = false;
+  FatalsAsError = false;
   SuppressSystemWarnings = false;
   SuppressAllDiagnostics = false;
   ElideType = true;

clang/lib/Basic/DiagnosticIDs.cpp

@@ -462,6 +462,12 @@ DiagnosticIDs::getDiagnosticSeverity(unsigned DiagID, SourceLocation Loc,
       Result = diag::Severity::Fatal;
   }
 
+  // If explicitly requested, map fatal errors to errors.
+  if (Result == diag::Severity::Fatal) {
+      if (Diag.FatalsAsError)
+        Result = diag::Severity::Error;
+  }
+
   // Custom diagnostics always are emitted in system headers.
   bool ShowInSystemHeader =
       !GetDiagInfo(DiagID) || GetDiagInfo(DiagID)->WarnShowInSystemHeader;

clang/test/Index/keep-going.cpp

@@ -0,0 +1,29 @@
+#include "missing1.h"
+
+template<class T>
+class A { T a; };
+
+class B : public A<int> { };
+
+#include "missing2.h"
+
+class C : public A<float> { };
+
+// RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_KEEP_GOING=1 c-index-test -test-print-type %s 2> %t.stderr.txt  | FileCheck %s
+// RUN: FileCheck -check-prefix CHECK-DIAG %s < %t.stderr.txt
+
+// CHECK: inclusion directive=missing1.h ((null)) [type=] [typekind=Invalid] [isPOD=0]
+// CHECK: inclusion directive=missing2.h ((null)) [type=] [typekind=Invalid] [isPOD=0]
+// CHECK: ClassTemplate=A:4:7 (Definition) [type=] [typekind=Invalid] [isPOD=0]
+// CHECK: TemplateTypeParameter=T:3:16 (Definition) [type=T] [typekind=Unexposed] [canonicaltype=type-parameter-0-0] [canonicaltypekind=Unexposed] [isPOD=0]
+// CHECK: FieldDecl=a:4:13 (Definition) [type=T] [typekind=Unexposed] [canonicaltype=type-parameter-0-0] [canonicaltypekind=Unexposed] [isPOD=0]
+// CHECK: TypeRef=T:3:16 [type=T] [typekind=Unexposed] [canonicaltype=type-parameter-0-0] [canonicaltypekind=Unexposed] [isPOD=0]
+// CHECK: ClassDecl=B:6:7 (Definition) [type=B] [typekind=Record] [isPOD=0]
+// CHECK: C++ base class specifier=A<int>:4:7 [access=public isVirtual=false] [type=A<int>] [typekind=Unexposed] [canonicaltype=A<int>] [canonicaltypekind=Record] [templateargs/1= [type=int] [typekind=Int]] [isPOD=0] [nbFields=1]
+// CHECK: TemplateRef=A:4:7 [type=] [typekind=Invalid] [isPOD=0]
+// CHECK: ClassDecl=C:10:7 (Definition) [type=C] [typekind=Record] [isPOD=0]
+// CHECK: C++ base class specifier=A<float>:4:7 [access=public isVirtual=false] [type=A<float>] [typekind=Unexposed] [canonicaltype=A<float>] [canonicaltypekind=Record] [templateargs/1= [type=float] [typekind=Float]] [isPOD=0] [nbFields=1]
+// CHECK: TemplateRef=A:4:7 [type=] [typekind=Invalid] [isPOD=0]
+
+// CHECK-DIAG: keep-going.cpp:1:10: error: 'missing1.h' file not found
+// CHECK-DIAG: keep-going.cpp:8:10: error: 'missing2.h' file not found

clang/tools/c-index-test/c-index-test.c

@@ -80,6 +80,8 @@ static unsigned getDefaultParsingOptions() {
     options |= CXTranslationUnit_IncludeBriefCommentsInCodeCompletion;
   if (getenv("CINDEXTEST_CREATE_PREAMBLE_ON_FIRST_PARSE"))
     options |= CXTranslationUnit_CreatePreambleOnFirstParse;
+  if (getenv("CINDEXTEST_KEEP_GOING"))
+    options |= CXTranslationUnit_KeepGoing;
 
   return options;
 }

clang/tools/libclang/CIndex.cpp

@@ -3158,6 +3158,9 @@ clang_parseTranslationUnit_Impl(CXIndex CIdx, const char *source_filename,
   IntrusiveRefCntPtr<DiagnosticsEngine>
     Diags(CompilerInstance::createDiagnostics(new DiagnosticOptions));
 
+  if (options & CXTranslationUnit_KeepGoing)
+    Diags->setFatalsAsError(true);
+
   // Recover resources if we crash before exiting this function.
   llvm::CrashRecoveryContextCleanupRegistrar<DiagnosticsEngine,
     llvm::CrashRecoveryContextReleaseRefCleanup<DiagnosticsEngine> >

clang/unittests/Basic/DiagnosticTest.cpp

@@ -46,4 +46,27 @@ TEST(DiagnosticTest, suppressAndTrap) {
   EXPECT_FALSE(Diags.hasUnrecoverableErrorOccurred());
 }
 
+// Check that FatalsAsErrors works as intended
+TEST(DiagnosticTest, fatalsAsErrors) {
+  DiagnosticsEngine Diags(new DiagnosticIDs(),
+                          new DiagnosticOptions,
+                          new IgnoringDiagConsumer());
+  Diags.setFatalsAsError(true);
+
+  // Diag that would set UncompilableErrorOccurred and ErrorOccurred.
+  Diags.Report(diag::err_target_unknown_triple) << "unknown";
+
+  // Diag that would set UnrecoverableErrorOccurred and ErrorOccurred.
+  Diags.Report(diag::err_cannot_open_file) << "file" << "error";
+
+  // Diag that would set FatalErrorOccurred
+  // (via non-note following a fatal error).
+  Diags.Report(diag::warn_mt_message) << "warning";
+
+  EXPECT_TRUE(Diags.hasErrorOccurred());
+  EXPECT_FALSE(Diags.hasFatalErrorOccurred());
+  EXPECT_TRUE(Diags.hasUncompilableErrorOccurred());
+  EXPECT_TRUE(Diags.hasUnrecoverableErrorOccurred());
+}
+
 }