[Clang] [NFC] Introduce a helper for emitting compatibility diagnostics (#132348)

This is a follow-up to #132129.

Currently, only `Parser` and `SemaBase` get a `DiagCompat()` helper; I’m
planning to keep refactoring compatibility warnings and add more helpers
to other classes as needed. I also refactored a single parser compat
warning just to make sure everything works properly when diagnostics
across multiple components (i.e. Sema and Parser in this case) are
involved.

Author: Sirraide

clang/include/clang/Basic/CMakeLists.txt

@@ -8,6 +8,11 @@ macro(clang_diag_gen component)
     -gen-clang-diags-enums -clang-component=${component}
     SOURCE Diagnostic.td
     TARGET ClangDiagnostic${component}Enums)
+
+  clang_tablegen(Diagnostic${component}CompatIDs.inc
+    -gen-clang-diags-compat-ids -clang-component=${component}
+    SOURCE Diagnostic.td
+    TARGET ClangDiagnostic${component}CompatIDs)
 endmacro(clang_diag_gen)
 
 clang_diag_gen(Analysis)
@@ -31,6 +36,11 @@ clang_tablegen(DiagnosticIndexName.inc -gen-clang-diags-index-name
   SOURCE Diagnostic.td
   TARGET ClangDiagnosticIndexName)
 
+clang_tablegen(DiagnosticAllCompatIDs.inc
+  -gen-clang-diags-compat-ids
+  SOURCE Diagnostic.td
+  TARGET ClangDiagnosticAllCompatIDs)
+
 clang_tablegen(AttrList.inc -gen-clang-attr-list
   -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
   SOURCE Attr.td

clang/include/clang/Basic/Diagnostic.td

@@ -155,6 +155,19 @@ class DefaultWarnNoWerror {
 }
 class DefaultRemark { Severity DefaultSeverity = SEV_Remark; }
 
+class CompatWarningId<string name, int std, string diag, string diag_pre> {
+  string Component = ?;
+  string Name = name;
+  string Diag = diag;
+  string DiagPre = diag_pre;
+  int Std = std;
+
+  // This is unused, but Tablegen will complain if it's missing because we define
+  // the compatibility ids in the same place as the other diagnostics (which means
+  // that we'll be inside a 'let CategoryName = "" in { ... }' block).
+  string CategoryName = ?;
+}
+
 // C++ compatibility warnings.
 multiclass CXXCompat<
     string message,
@@ -178,6 +191,11 @@ multiclass CXXCompat<
                                      "CXX98Compat",
                                      "CXXPre"#std_ver#"Compat"))>,
         DefaultIgnore;
+
+    def : CompatWarningId<
+        NAME, std_ver,
+        "compat_cxx"#std_ver#"_"#NAME,
+        "compat_pre_cxx"#std_ver#"_"#NAME>;
 }
 
 // These generate pairs of C++ compatibility warnings of the form:

clang/include/clang/Basic/DiagnosticAST.h

@@ -36,6 +36,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticASTCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICAST_H

clang/include/clang/Basic/DiagnosticAnalysis.h

@@ -35,6 +35,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticAnalysisCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICANALYSIS_H

clang/include/clang/Basic/DiagnosticComment.h

@@ -36,6 +36,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticCommentCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICCOMMENT_H

clang/include/clang/Basic/DiagnosticCrossTU.h

@@ -36,6 +36,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticCrossTUCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICCROSSTU_H

clang/include/clang/Basic/DiagnosticDriver.h

@@ -36,6 +36,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticDriverCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICDRIVER_H

clang/include/clang/Basic/DiagnosticFrontend.h

@@ -36,6 +36,18 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // end namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticFrontendCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICFRONTEND_H

clang/include/clang/Basic/DiagnosticIDs.h

@@ -25,6 +25,7 @@
 namespace clang {
   class DiagnosticsEngine;
   class DiagnosticBuilder;
+  class LangOptions;
   class SourceLocation;
 
   // Import the diagnostic enums themselves.
@@ -104,6 +105,18 @@ namespace clang {
     };
   }
 
+  namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                \
+    }                                                                          \
+    ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticCommonCompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+  } // end namespace diag_compat
+
 class DiagnosticMapping {
   LLVM_PREFERRED_TYPE(diag::Severity)
   unsigned Severity : 3;
@@ -464,6 +477,11 @@ class DiagnosticIDs : public RefCountedBase<DiagnosticIDs> {
   /// given group name.
   static StringRef getNearestOption(diag::Flavor Flavor, StringRef Group);
 
+  /// Get the appropriate diagnostic Id to use for issuing a compatibility
+  /// diagnostic. For use by the various DiagCompat() helpers.
+  static unsigned getCXXCompatDiagId(const LangOptions &LangOpts,
+                                     unsigned CompatDiagId);
+
 private:
   /// Classify the specified diagnostic ID into a Level, consumable by
   /// the DiagnosticClient.

clang/include/clang/Basic/DiagnosticInstallAPI.h

@@ -35,5 +35,17 @@ enum {
 #undef DIAG_ENUM_ITEM
 #undef DIAG_ENUM
 } // namespace diag
+
+namespace diag_compat {
+#define DIAG_COMPAT_IDS_BEGIN() enum {
+#define DIAG_COMPAT_IDS_END()                                                  \
+  }                                                                            \
+  ;
+#define DIAG_COMPAT_ID(IDX, NAME, ...) NAME = IDX,
+#include "clang/Basic/DiagnosticInstallAPICompatIDs.inc"
+#undef DIAG_COMPAT_ID
+#undef DIAG_COMPAT_IDS_BEGIN
+#undef DIAG_COMPAT_IDS_END
+} // end namespace diag_compat
 } // namespace clang
 #endif // LLVM_CLANG_BASIC_DIAGNOSTICINSTALLAPI_H