[clangd] Dont provide locations for non-existent files.

[kadircet]

Summary

We were getting assertion errors when we had bad file names, instead we
should skip those.

[hokein]

unittests/clangd/SymbolCollectorTests.cpp

1036 ↗

(On Diff #176646)

We handled this case previously, but the code was removed in rL346488 (looks like sam missed the case where we don't use preamble, like building static index). I think we should bring the logic back -- revert the change of isSpelledInSourceCode and add SymbolCollectorTest, SymbolFormedByCLI should be enough.

[kadircet]

• Revert rL346488 partially.

[hokein]

thanks!

clang-tools-extra/trunk/clangd/AST.cpp

 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ScopedPrinter.h"
 
 using namespace llvm;
 namespace clang {
 namespace clangd {
 
 // Returns true if the complete name of decl \p D is spelled in the source code.
-// This is not the case for symbols formed via macro concatenation.
-// (We used to attempt to treat names spelled on the command-line this way too,
-// but the preamble doesn't preserve the required information).
+// This is not the case for:
+//   * symbols formed via macro concatenation, the spelling location will
+//     be "<scratch space>"
+//   * symbols controlled and defined by a compile command-line option
+//     `-DName=foo`, the spelling location will be "<command line>".
 bool isSpelledInSourceCode(const Decl *D) {
   const auto &SM = D->getASTContext().getSourceManager();
   auto Loc = D->getLocation();
   // FIXME: Revisit the strategy, the heuristic is limitted when handling
   // macros, we should use the location where the whole definition occurs.
   if (Loc.isMacroID()) {
     std::string PrintLoc = SM.getSpellingLoc(Loc).printToString(SM);
-    if (StringRef(PrintLoc).startswith("<scratch"))
+    if (StringRef(PrintLoc).startswith("<scratch") ||
+        StringRef(PrintLoc).startswith("<command line>"))
       return false;
   }
   return true;
 }
 
 bool isImplementationDetail(const Decl *D) { return !isSpelledInSourceCode(D); }
 
 SourceLocation findNameLoc(const clang::Decl* D) {

clang-tools-extra/trunk/unittests/clangd/SymbolCollectorTests.cpp

EXPECT_THAT(
       Symbols,
       UnorderedElementsAre(
           AllOf(QName("abc_Test"), DeclRange(Header.range("expansion")),
                 DeclURI(TestHeaderURI)),
           AllOf(QName("Test"), DeclRange(Header.range("spelling")),
                 DeclURI(TestHeaderURI))));
 }
 
+TEST_F(SymbolCollectorTest, SymbolFormedByCLI) {
+  Annotations Header(R"(
+    #ifdef NAME
+    class $expansion[[NAME]] {};
+    #endif
+  )");
+  runSymbolCollector(Header.code(), /*Main=*/"", /*ExtraArgs=*/{"-DNAME=name"});
+  EXPECT_THAT(Symbols, UnorderedElementsAre(AllOf(
+                           QName("name"), DeclRange(Header.range("expansion")),
+                           DeclURI(TestHeaderURI))));
+}
+
 TEST_F(SymbolCollectorTest, IgnoreSymbolsInMainFile) {
   const std::string Header = R"(
     class Foo {};
     void f1();
     inline void f2() {}
   )";
   const std::string Main = R"(
     namespace {