[lld-macho] Make ObjC category checker print the source file name of …

[alx32]

When printing category conflicts in the ObjC category checker, also print the source file name of the problematic categories. Currently we only print the object file name. This change is mostly useful only for thinLTO builds, where the object file name will be of form 999.arm64.lto.o and thus does not reveal any information about the original source file.

[llvmbot]

@llvm/pr-subscribers-lld

@llvm/pr-subscribers-lld-macho

Author: None (alx32)

Changes

Summary: When printing category conflicts in the ObjC category checker, also print the source file name of the problematic categories. Currently we only print the object file name. This change is mostly useful only for thinLTO builds, where the object file name will be of form 999.arm64.lto.o and thus does not reveal any information about the original source file.

Test Plan: Added test case + check-lld.

---

Full diff: https://github.com/llvm/llvm-project/pull/80221.diff

2 Files Affected:

• (modified) lld/MachO/ObjC.cpp (+14-2)
• (modified) lld/test/MachO/objc-category-conflicts.s (+31-2)

diff --git a/lld/MachO/ObjC.cpp b/lld/MachO/ObjC.cpp
index 7e8cec026d2f7..02009d4ed59cf 100644
--- a/lld/MachO/ObjC.cpp
+++ b/lld/MachO/ObjC.cpp
@@ -237,12 +237,24 @@ void ObjcCategoryChecker::parseMethods(const ConcatInputSection *methodsIsec,
     StringRef newCatName =
         getReferentString(*containerIsec->getRelocAt(catLayout.nameOffset));
 
+    auto formatObjAndSrcFileName = [](const InputSection *section) {
+      lld::macho::InputFile *inputFile = section->getFile();
+      std::string result = toString(inputFile);
+
+      auto objFile = dyn_cast_or_null<ObjFile>(inputFile);
+      if (objFile && objFile->compileUnit) {
+        result += " (" + objFile->sourceFile() + ")";
+      }
+
+      return result;
+    };
+
     StringRef containerType = mc.kind == MCK_Category ? "category" : "class";
     warn("method '" + methPrefix + methodName.val() +
          "' has conflicting definitions:\n>>> defined in category " +
-         newCatName + " from " + toString(containerIsec->getFile()) +
+         newCatName + " from " + formatObjAndSrcFileName(containerIsec) +
          "\n>>> defined in " + containerType + " " + containerName + " from " +
-         toString(mc.isec->getFile()));
+         formatObjAndSrcFileName(mc.isec));
   }
 }
 
diff --git a/lld/test/MachO/objc-category-conflicts.s b/lld/test/MachO/objc-category-conflicts.s
index 59a9ed50eb055..4ac8dc72c8668 100644
--- a/lld/test/MachO/objc-category-conflicts.s
+++ b/lld/test/MachO/objc-category-conflicts.s
@@ -3,6 +3,9 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat1.s -o %t/cat1.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat2.s -o %t/cat2.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/klass.s -o %t/klass.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat1.s -g -o %t/cat1_w_sym.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat2.s -g -o %t/cat2_w_sym.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/klass.s -g -o %t/klass_w_sym.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat1.s --defsym MAKE_LOAD_METHOD=1 -o %t/cat1-with-load.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/cat2.s --defsym MAKE_LOAD_METHOD=1 -o %t/cat2-with-load.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-macos11.0 -I %t %t/klass.s --defsym MAKE_LOAD_METHOD=1 -o %t/klass-with-load.o
@@ -14,6 +17,14 @@
 # RUN: %no-fatal-warnings-lld --check-category-conflicts -dylib -lobjc %t/libklass.dylib %t/cat1.o \
 # RUN:   %t/cat2.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=CATCAT
 
+# RUN: %no-fatal-warnings-lld --check-category-conflicts -dylib -lobjc %t/klass_w_sym.o %t/cat1_w_sym.o %t/cat2_w_sym.o -o \
+# RUN:   /dev/null 2>&1 | FileCheck %s --check-prefixes=CATCLS_W_SYM,CATCAT_W_SYM
+# RUN: %no-fatal-warnings-lld --check-category-conflicts -dylib -lobjc %t/libklass.dylib %t/cat1_w_sym.o \
+# RUN:   %t/cat2_w_sym.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=CATCAT_W_SYM
+
+# RUN: %no-fatal-warnings-lld --check-category-conflicts -dylib -lobjc %t/klass.o %t/cat1.o %t/cat2.o -o \
+# RUN:   /dev/null 2>&1 | FileCheck %s --check-prefixes=CATCLS,CATCAT
+
 ## Check that we don't emit spurious warnings around the +load method while
 ## still emitting the other warnings. Note that we have made separate
 ## `*-with-load.s` files for ease of comparison with ld64; ld64 will not warn
@@ -45,6 +56,24 @@
 # CATCAT-NEXT: >>> defined in category Cat2 from {{.*}}cat2{{.*}}.o
 # CATCAT-NEXT: >>> defined in category Cat1 from {{.*}}cat1{{.*}}.o
 
+
+# CATCLS_W_SYM:      warning: method '+s1' has conflicting definitions:
+# CATCLS_W_SYM-NEXT: >>> defined in category Cat1 from {{.*}}cat1_w_sym{{.*}}.o ({{.*}}cat1.s{{.*}})
+# CATCLS_W_SYM-NEXT: >>> defined in class Foo from {{.*}}klass_w_sym{{.*}}.o ({{.*}}klass.s{{.*}})
+
+# CATCLS_W_SYM:      warning: method '-m1' has conflicting definitions:
+# CATCLS_W_SYM-NEXT: >>> defined in category Cat1 from {{.*}}cat1_w_sym{{.*}}.o ({{.*}}cat1.s{{.*}})
+# CATCLS_W_SYM-NEXT: >>> defined in class Foo from {{.*}}klass_w_sym{{.*}}.o ({{.*}}klass.s{{.*}})
+
+# CATCAT_W_SYM:      warning: method '+s2' has conflicting definitions:
+# CATCAT_W_SYM-NEXT: >>> defined in category Cat2 from {{.*}}cat2_w_sym{{.*}}.o ({{.*}}cat2.s{{.*}})
+# CATCAT_W_SYM-NEXT: >>> defined in category Cat1 from {{.*}}cat1_w_sym{{.*}}.o ({{.*}}cat1.s{{.*}})
+
+# CATCAT_W_SYM:      warning: method '-m2' has conflicting definitions:
+# CATCAT_W_SYM-NEXT: >>> defined in category Cat2 from {{.*}}cat2_w_sym{{.*}}.o ({{.*}}cat2.s{{.*}})
+# CATCAT_W_SYM-NEXT: >>> defined in category Cat1 from {{.*}}cat1_w_sym{{.*}}.o ({{.*}}cat1.s{{.*}})
+
+
 #--- cat1.s
 
 .include "objc-macros.s"
@@ -55,7 +84,7 @@
 ## +(void) s1;
 ## +(void) s2;
 ## @end
-## 
+##
 ## @implementation Foo(Cat1)
 ## -(void) m1 {}
 ## -(void) m2 {}
@@ -114,7 +143,7 @@ __OBJC_$_CATEGORY_CLASS_METHODS_Foo_$_Cat1:
 ## -(void) m2;
 ## +(void) s2;
 ## @end
-## 
+##
 ## @implementation Foo(Cat2)
 ## -(void) m2 {}
 ## +(void) s2 {}

[kyulee-com]

This change is mostly useful only for thinLTO builds

I'm curious how it looks like with (full)lto builds where bitcodes are merged.

[alx32]

I'm curious how it looks like with (full)lto builds where bitcodes are merged.

Good catch. In that case the file paths won't be valid. i.e it'll be something like:

defined in category TheCategory from /tmp/lto.tmp (RandomFile.mm)

However, I don't see an easy way to tell at this location if we're within the LTO scenario.

[thevinster]

LGTM, just a minor nit.

However, I don't see an easy way to tell at this location if we're within the LTO scenario.

That's unfortunate. Spitting out some RandomFile might lead someone on a wild goose chase and I would prefer (if possible) to not even emit the source file in that scenario. In any case, this is already a quality improvement.

[kyulee-com]

lgtm