[clang] c2377ea - [clang][Tooling] Prefer -x over -std when interpolating

[Kadir Cetinkaya via cfe-commits]

Author: Kadir Cetinkaya
Date: 2019-12-20T11:10:36+01:00
New Revision: c2377eae286bbe616267bef772ee736b030dd007

URL: https://github.com/llvm/llvm-project/commit/c2377eae286bbe616267bef772ee736b030dd007
DIFF: https://github.com/llvm/llvm-project/commit/c2377eae286bbe616267bef772ee736b030dd007.diff

LOG: [clang][Tooling] Prefer -x over -std when interpolating

Summary:
Currently interpolation logic prefers -std over -x. But the latter is a
more strong signal, so this patch inverts the order and only makes use of -std
if -x didn't exist.

Fixes https://github.com/clangd/clangd/issues/185

Thanks @sammccall for tracking this down!

Reviewers: sammccall

Subscribers: ilya-biryukov, usaxena95, cfe-commits, sammccall

Tags: #clang

Differential Revision: https://reviews.llvm.org/D71727

Added: 
    

Modified: 
    clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
    clang/unittests/Tooling/CompilationDatabaseTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
index 59b66abe65e9..2cc819a498c6 100644
--- a/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
+++ b/clang/lib/Tooling/InterpolatingCompilationDatabase.cpp
@@ -191,7 +191,8 @@ struct TransferableCommand {
                              OldArgs.data() + OldPos, OldArgs.data() + Pos);
     }
 
-    if (Std != LangStandard::lang_unspecified) // -std take precedence over -x
+    // Make use of -std iff -x was missing.
+    if (Type == types::TY_INVALID && Std != LangStandard::lang_unspecified)
       Type = toType(LangStandard::getLangStandardForKind(Std).getLanguage());
     Type = foldType(*Type);
     // The contract is to store None instead of TY_INVALID.

diff  --git a/clang/unittests/Tooling/CompilationDatabaseTest.cpp b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
index 91685c0d0c73..56ebadc5eae2 100644
--- a/clang/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/clang/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -749,6 +749,7 @@ TEST_F(InterpolateTest, Language) {
   add("dir/foo.cpp", "-std=c++17");
   add("dir/bar.c", "");
   add("dir/baz.cee", "-x c");
+  add("dir/aux.cpp", "-std=c++17 -x objective-c++");
 
   // .h is ambiguous, so we add explicit language flags
   EXPECT_EQ(getCommand("foo.h"),
@@ -767,6 +768,9 @@ TEST_F(InterpolateTest, Language) {
   Entries.erase(path(StringRef("dir/bar.c")));
   // Now we transfer across languages, so drop -std too.
   EXPECT_EQ(getCommand("foo.c"), "clang -D dir/foo.cpp");
+  // Prefer -x over -std when overriding language.
+  EXPECT_EQ(getCommand("aux.h"),
+            "clang -D dir/aux.cpp -x objective-c++-header -std=c++17");
 }
 
 TEST_F(InterpolateTest, Strip) {