[clang] [clang][frontend] Make DumpModuleInfoAction emit the full macro (PR #85745)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-modules

Author: Zhang Yi (zhanyi22333)

<details>
<summary>Changes</summary>

This PR works on the TODO `Emit the macro definition bodies completely`  in FrontendActions.cpp. Emiting the macro definition bodies completely can help user get more details about macro.

The beginning of macro-body string is get by MacroInfo definition location in SourceManager. Then it compute the macro-body string length by locate the '\n' but not '\\\n'. After that, the string is getted and reformmatted into one line. 
When cannot get the MacroInfo, it will only emit the name of macro definition. 

@<!-- -->rjmccall @<!-- -->kpneal @<!-- -->zahiraam @<!-- -->efriedma-quic @<!-- -->vgvassilev @<!-- -->junaire

---
Full diff: https://github.com/llvm/llvm-project/pull/85745.diff


2 Files Affected:

- (modified) clang/lib/Frontend/FrontendActions.cpp (+29-3) 
- (modified) clang/test/Modules/cxx20-module-file-info-macros.cpp (+4-4) 


``````````diff
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index 81fcd8d5ae9bd3..aa2781daef3988 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -925,15 +925,41 @@ void DumpModuleInfoAction::ExecuteAction() {
 
     // Emit the macro definitions in the module file so that we can know how
     // much definitions in the module file quickly.
-    // TODO: Emit the macro definition bodies completely.
     if (auto FilteredMacros = llvm::make_filter_range(
             R->getPreprocessor().macros(),
             [](const auto &Macro) { return Macro.first->isFromAST(); });
         !FilteredMacros.empty()) {
       Out << "   Macro Definitions:\n";
       for (/*<IdentifierInfo *, MacroState> pair*/ const auto &Macro :
-           FilteredMacros)
-        Out << "     " << Macro.first->getName() << "\n";
+           FilteredMacros) {
+        SourceManager &SM = PP.getSourceManager();
+        clang::MacroInfo *MacroInfo = PP.getMacroInfo(Macro.first);
+        if (MacroInfo) {
+          bool isInvalid=true;
+          const char* ContentStrPtr=SM.getCharacterData(MacroInfo->getDefinitionLoc(),&isInvalid);
+          if (!isInvalid) {
+          int ContentLength=0;
+          while ( !(*(ContentStrPtr+ContentLength)=='\n') ||  *(ContentStrPtr+ContentLength-1)=='\\') {
+            ContentLength++;
+          }
+          std::string MacroContent=std::string(ContentStrPtr,ContentLength);
+          // Replace '\\\n' with space
+          size_t pos = 0;
+          while ((pos = MacroContent.find("\\\n", pos)) != std::string::npos) {
+            MacroContent.replace(pos, 2," ");
+          }
+          // Merge spaces
+          auto new_end = std::unique(MacroContent.begin(), MacroContent.end(), [](char a, char b) {
+            return a == ' ' && b == ' ';
+          });
+          MacroContent.erase(new_end, MacroContent.end());
+          Out << "     " << MacroContent << '\n';
+          }
+        }
+        else {
+          Out << "     " << Macro.first->getName() << "\n";
+        }
+      }
     }
 
     // Now let's print out any modules we did not see as part of the Primary.
diff --git a/clang/test/Modules/cxx20-module-file-info-macros.cpp b/clang/test/Modules/cxx20-module-file-info-macros.cpp
index 3b67e9b9acd410..fad218bdfc9638 100644
--- a/clang/test/Modules/cxx20-module-file-info-macros.cpp
+++ b/clang/test/Modules/cxx20-module-file-info-macros.cpp
@@ -37,8 +37,8 @@
 
 // CHECK: Macro Definitions:
 // CHECK-DAG: REDEFINE
-// CHECK-DAG: FUNC_Macro
-// CHECK-DAG: CONSTANT
+// CHECK-DAG: FUNC_Macro(X) (X+1)
+// CHECK-DAG: CONSTANT 43
 // CHECK-DAG: FOO
 // CHECK-NEXT: ===
 
@@ -46,8 +46,8 @@
 #include "foo.h"
 #undef REDEFINE
 // CHECK: Macro Definitions:
-// CHECK-DAG: CONSTANT
-// CHECK-DAG: FUNC_Macro
+// CHECK-DAG: CONSTANT 43
+// CHECK-DAG: FUNC_Macro(X) (X+1)
 // CHECK-DAG: FOO
 // CHECK-NEXT: ===
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/85745