From 923e78785d8505d16026f1c2b78079b79adac8fa Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Thu, 28 Jan 2016 23:18:18 -0700
Subject: [PATCH] attempt to get preprocessor entities from libclang

I'm pretty sure it's impossible, the API does not
expose the macro expansion value

and the source location points to the macro's name,
not its value.
---
 src/parseh.cpp | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/parseh.cpp b/src/parseh.cpp
index 5a829edc4b..e87daa5fc6 100644
--- a/src/parseh.cpp
+++ b/src/parseh.cpp
@@ -713,6 +713,30 @@ static void render_aliases(Context *c) {
     }
 }
 
+static void process_preprocessor_entities(Context *c, ASTUnit &unit) {
+    for (PreprocessedEntity *entity : unit.getLocalPreprocessingEntities()) {
+        switch (entity->getKind()) {
+            case PreprocessedEntity::InvalidKind:
+            case PreprocessedEntity::InclusionDirectiveKind:
+            case PreprocessedEntity::MacroExpansionKind:
+                continue;
+            case PreprocessedEntity::MacroDefinitionKind:
+                {
+                    MacroDefinitionRecord *macro = static_cast<MacroDefinitionRecord *>(entity);
+                    const char *name = macro->getName()->getNameStart();
+                    fprintf(stderr, "definition macro: %s\n", name);
+                    SourceRange range = macro->getSourceRange();
+                    SourceLocation begin_loc = range.getBegin();
+                    SourceLocation end_loc = range.getEnd();
+
+                    const char *start_c = c->source_manager->getCharacterData(begin_loc);
+                    const char *end_c = c->source_manager->getCharacterData(end_loc);
+                    fprintf(stderr, "source: '%.*s'\n", (int)(end_c - start_c), start_c);
+                }
+        }
+    }
+}
+
 int parse_h_buf(ImportTableEntry *import, ZigList<ErrorMsg *> *errors, Buf *source,
         const char **args, int args_len, const char *libc_include_path, bool warnings_on)
 {
@@ -774,6 +798,12 @@ int parse_h_file(ImportTableEntry *import, ZigList<ErrorMsg *> *errors,
 
     // we don't need spell checking and it slows things down
     clang_argv->append("-fno-spell-checking");
+
+    // this gives us access to preprocessing entities, presumably at
+    // the cost of performance
+    clang_argv->append("-Xclang");
+    clang_argv->append("-detailed-preprocessing-record");
+
     // to make the end argument work
     clang_argv->append(nullptr);
 
@@ -844,6 +874,8 @@ int parse_h_file(ImportTableEntry *import, ZigList<ErrorMsg *> *errors,
     c->root = create_node(c, NodeTypeRoot);
     ast_unit->visitLocalTopLevelDecls(c, decl_visitor);
 
+    process_preprocessor_entities(c, *ast_unit);
+
     render_aliases(c);
 
     normalize_parent_ptrs(c->root);