Use toString to print out garbage-collected sections.

[ruiu]

Summary

Currently, archive file name is missing in this message. In general,
we should avoid constructing strings in an ad-hoc manner and instead
use toString() to get consistent output strings.

[sbc100]

Why not change wasm at the same time?

ELF/MarkLive.cpp

template <class ELFT> void elf::markLive() {
 
   // Follow the graph to mark all live sections.
   doGcSections<ELFT>();
 
   // Report garbage-collected sections.
   if (Config->PrintGcSections)
     for (InputSectionBase *Sec : InputSections)
       if (!Sec->Live)
-        message("removing unused section from '" + Sec->Name + "' in file '" +
-                Sec->File->getName() + "'");
+        message("removing unused section " + toString(Sec));
 }
 
 template void elf::markLive<ELF32LE>();
 template void elf::markLive<ELF32BE>();
 template void elf::markLive<ELF64LE>();
 template void elf::markLive<ELF64BE>();

test/ELF/comdat.s

 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/comdat.s -o %t2.o
 // RUN: ld.lld -shared %t.o %t.o %t2.o -o %t
 // RUN: llvm-objdump -d %t | FileCheck %s
 // RUN: llvm-readobj -s -t %t | FileCheck --check-prefix=READ %s
 // REQUIRES: x86
 
 // Check that we don't crash with --gc-section and that we print a list of
 // reclaimed sections on stderr.
 // RUN: ld.lld --gc-sections --print-gc-sections -shared %t.o %t.o %t2.o -o %t \
 // RUN:   2>&1 | FileCheck --check-prefix=GC %s
-// GC: removing unused section from '.text' in file
-// GC: removing unused section from '.text3' in file
-// GC: removing unused section from '.text' in file
-// GC: removing unused section from '.text' in file
+// GC: removing unused section {{.*}}.o:(.text)
+// GC: removing unused section {{.*}}.o:(.text3)
+// GC: removing unused section {{.*}}.o:(.text)
+// GC: removing unused section {{.*}}.o:(.text)
 
         .section  .text2,"axG",@progbits,foo,comdat,unique,0
 foo:
         nop
 
 // CHECK: Disassembly of section .text2:
 // CHECK-NEXT: foo:
 // CHECK-NEXT:   1000: {{.*}}  nop

test/ELF/emit-relocs-gc.s

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
 
 ## Show that we emit .rela.bar and .rela.text when GC is disabled.
 # RUN: ld.lld --emit-relocs %t.o -o %t
 # RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=NOGC
 # NOGC: .rela.text
 # NOGC: .rela.bar
 
 ## GC collects .bar section and we exclude .rela.bar from output. We keep
 ## .rela.text because we keep .text.
 # RUN: ld.lld --gc-sections --emit-relocs --print-gc-sections %t.o -o %t \
 # RUN:   | FileCheck --check-prefix=MSG %s
-# MSG: removing unused section from '.bar' in file
-# MSG: removing unused section from '.rela.bar' in file
+# MSG: removing unused section {{.*}}.o:(.bar)
+# MSG: removing unused section {{.*}}.o:(.rela.bar)
 # RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=GC
 # GC-NOT:  rela.bar
 # GC:      rela.text
 # GC-NOT:  rela.bar
 
 .section .bar,"a"
 .quad .bar
 
 .text
 relocs:
 .quad _start
 
 .global _start
 _start:
  nop

test/ELF/gc-sections-print.s

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 # RUN: ld.lld %t --gc-sections --print-gc-sections -o %t2 2>&1 | FileCheck -check-prefix=PRINT %s
 
-# PRINT:      removing unused section from '.text.x' in file
-# PRINT-NEXT: removing unused section from '.text.y' in file
+# PRINT:      removing unused section {{.*}}:(.text.x)
+# PRINT-NEXT: removing unused section {{.*}}:(.text.y)
 
 # RUN: ld.lld %t --gc-sections --print-gc-sections --no-print-gc-sections -o %t2 >& %t.log
 # RUN: echo >> %t.log
 # RUN: FileCheck -check-prefix=NOPRINT %s < %t.log
 
 # NOPRINT-NOT: removing
 
 .globl _start

test/ELF/linkerscript/discard-print-gc.s

 
 # RUN: echo "SECTIONS { .foo : { *(.foo) } }" > %t2.script
 # RUN: ld.lld -o %t.so -T %t2.script --gc-sections %t.o --print-gc-sections -shared 2>&1 | \
 # RUN:   FileCheck -check-prefix=CHECK %s
 
 .section .foo,"a"
 .quad 0
 
-# CHECK: removing unused section from '.foo'
-# QUIET-NOT: removing unused section from '.foo'
+# CHECK: removing unused section {{.*}}:(.foo)
+# QUIET-NOT: removing unused section {{.*}}:(.foo)