Reland [clang][Sema, Lex, Parse] Preprocessor embed in C and C++ (#95802)

This commit implements the entirety of the now-accepted [N3017
-Preprocessor
Embed](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3017.htm) and
its sister C++ paper [p1967](https://wg21.link/p1967). It implements
everything in the specification, and includes an implementation that
drastically improves the time it takes to embed data in specific
scenarios (the initialization of character type arrays). The mechanisms
used to do this are used under the "as-if" rule, and in general when the
system cannot detect it is initializing an array object in a variable
declaration, will generate EmbedExpr AST node which will be expanded by
AST consumers (CodeGen or constant expression evaluators) or expand
embed directive as a comma expression.

This reverts commit
https://github.com/llvm/llvm-project/commit/682d461d5a231cee54d65910e6341769419a67d7.

---------

Co-authored-by: The Phantom Derpstorm <phdofthehouse@gmail.com>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Co-authored-by: H. Vetinari <h.vetinari@gmx.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
index 369816e..528eae2 100644
--- a/clang/lib/Frontend/DependencyFile.cpp
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -62,6 +62,19 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
                                     /*IsMissing=*/false);
   }
 
+  void EmbedDirective(SourceLocation, StringRef, bool,
+                      OptionalFileEntryRef File,
+                      const LexEmbedParametersResult &) override {
+    assert(File && "expected to only be called when the file is found");
+    StringRef FileName =
+        llvm::sys::path::remove_leading_dotslash(File->getName());
+    DepCollector.maybeAddDependency(FileName,
+                                    /*FromModule*/ false,
+                                    /*IsSystem*/ false,
+                                    /*IsModuleFile*/ false,
+                                    /*IsMissing*/ false);
+  }
+
   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
                           StringRef FileName, bool IsAngled,
                           CharSourceRange FilenameRange,
@@ -77,6 +90,18 @@ struct DepCollectorPPCallbacks : public PPCallbacks {
     // Files that actually exist are handled by FileChanged.
   }
 
+  void HasEmbed(SourceLocation, StringRef, bool,
+                OptionalFileEntryRef File) override {
+    if (!File)
+      return;
+    StringRef Filename =
+        llvm::sys::path::remove_leading_dotslash(File->getName());
+    DepCollector.maybeAddDependency(Filename,
+                                    /*FromModule=*/false, false,
+                                    /*IsModuleFile=*/false,
+                                    /*IsMissing=*/false);
+  }
+
   void HasInclude(SourceLocation Loc, StringRef SpelledFilename, bool IsAngled,
                   OptionalFileEntryRef File,
                   SrcMgr::CharacteristicKind FileType) override {