[clang/Lexer] Enhance `Lexer::getImmediateMacroNameForDiagnostics` to return a result from non-file buffers

[akyrtzi]

Summary

Use SourceManager::isWrittenInScratchSpace() to specifically check for token paste or stringization, instead of
excluding all non-file buffers. This allows diagnostics to mention macro names that were defined from the command-line.

[steven_wu]

LGTM

clang/lib/Lex/Lexer.cpp

1050–1054

nit: isn't FileID or from scratch space

[akyrtzi]

Adjust code comment.

clang/lib/Lex/Lexer.cpp

 
 StringRef Lexer::getImmediateMacroNameForDiagnostics(
     SourceLocation Loc, const SourceManager &SM, const LangOptions &LangOpts) {
   assert(Loc.isMacroID() && "Only reasonable to call this on macros");
   // Walk past macro argument expansions.
   while (SM.isMacroArgExpansion(Loc))
     Loc = SM.getImmediateExpansionRange(Loc).getBegin();
 
-  // If the macro's spelling has no FileID, then it's actually a token paste
-  // or stringization (or similar) and not a macro at all.
-  if (!SM.getFileEntryForID(SM.getFileID(SM.getSpellingLoc(Loc))))
+  // If the macro's spelling isn't FileID or from scratch space, then it's
+  // actually a token paste or stringization (or similar) and not a macro at
+  // all.
+  SourceLocation SpellLoc = SM.getSpellingLoc(Loc);
+  if (!SpellLoc.isFileID() || SM.isWrittenInScratchSpace(SpellLoc))
     return {};
 
   // Find the spelling location of the start of the non-argument expansion
   // range. This is where the macro name was spelled in order to begin
   // expanding this macro.
   Loc = SM.getSpellingLoc(SM.getImmediateExpansionRange(Loc).getBegin());
 
   // Dig out the buffer where the macro name was spelled and the extents of the

clang/test/Modules/build-fail-notes.m

 // RUN: rm -rf %t
 // RUN: not %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -F %S/Inputs -DgetModuleVersion="epic fail" %s 2>&1 | FileCheck %s
 
 @import DependsOnModule;
 
 // CHECK: While building module 'DependsOnModule' imported from
 // CHECK: While building module 'Module' imported from
 // CHECK: error: expected ';' after top level declarator
-// CHECK: note: expanded from here
+// CHECK: note: expanded from macro 'getModuleVersion'
 // CHECK: fatal error: could not build module 'Module'
 // CHECK: fatal error: could not build module 'DependsOnModule'
 // CHECK-NOT: error:
 
 // RUN: not %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -F %S/Inputs %s -fdiagnostics-show-note-include-stack 2>&1 | FileCheck -check-prefix=CHECK-REDEF %s
 extern int Module;
 
 // CHECK-REDEF: In module 'DependsOnModule' imported from
 // CHECK-REDEF: In module 'Module' imported from
 // CHECK-REDEF: Module.h:15:12: note: previous definition is here
 
 // RUN: not %clang_cc1 -Wincomplete-umbrella -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -F %S/Inputs -DgetModuleVersion="epic fail" -serialize-diagnostic-file %t/tmp.diag %s 2>&1
 // RUN: c-index-test -read-diagnostics %t/tmp.diag 2>&1 | FileCheck -check-prefix=CHECK-SDIAG %s
 
 // CHECK-SDIAG: Module.h:9:13: error: expected ';' after top level declarator
 // CHECK-SDIAG: build-fail-notes.m:4:9: note: while building module 'DependsOnModule' imported from
 // CHECK-SDIAG: DependsOnModule.h:1:10: note: while building module 'Module' imported from
-// CHECK-SDIAG: note: expanded from here
+// CHECK-SDIAG: note: expanded from macro 'getModuleVersion'
 // CHECK-SDIAG: warning: umbrella header for module 'Module' does not include header 'NotInModule.h' [-Wincomplete-umbrella]
 // CHECK-SDIAG: DependsOnModule.h:1:10: fatal: could not build module 'Module'
 // CHECK-SDIAG: build-fail-notes.m:4:9: note: while building module 'DependsOnModule' imported from
 

clang/test/Modules/epic-fail.m

 // RUN: rm -rf %t
 // RUN: not %clang_cc1 -fmodules-cache-path=%t -fmodules -fimplicit-module-maps -F %S/Inputs -DgetModuleVersion="epic fail" %s 2>&1 | FileCheck %s
 
 @import Module;
 @import DependsOnModule;
 
 // CHECK: While building module 'Module' imported from
 // CHECK: error: expected ';' after top level declarator
-// CHECK: note: expanded from here
+// CHECK: note: expanded from macro 'getModuleVersion'
 // CHECK: fatal error: could not build module 'Module'
 // CHECK: While building module 'DependsOnModule' imported from
 // CHECK: fatal error: could not build module 'Module'
 // CHECK-NOT: error: