dsymutil/modules: Reword the warning for static libraries without module caches

In addition to clarifying the warning message this contains a minor functional
change in that it now warns if the *immediate* parent directory in which the
missing PCM is expected to be isn't found.

This patch also includes a more comprehensive testcase.

rdar://problem/25860711

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270269 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/dsymutil/X86/module-warnings.test

@@ -0,0 +1,53 @@
+# Compile with:
+#    cat >modules.modulemap <<EOF
+#      module Foo {
+#        header "Foo.h"
+#        export *
+#      }
+#      module Bar {
+#        header "Bar.h"
+#        export *
+#      }
+# EOF
+#    echo 'typedef int bar;' >Bar.h
+#    echo '@import Bar; typedef bar foo;' >Foo.h
+#    echo '@import Foo; foo f() { return 0; }' >module-warnings.m
+#    clang -cc1 -emit-obj -fmodules -fmodule-map-file=modules.modulemap \
+#      -fmodule-format=obj -debug-info-kind=standalone -dwarf-ext-refs \
+#      -fmodules-cache-path=ModuleCache \
+#      -fdisable-module-hash module-warnings.m -o 1.o
+#
+# Test for module-related warnings.
+#
+# RUN: rm -rf %t.dir && mkdir %t.dir && mkdir %t.dir/ModuleCache
+# RUN: cp %p/../Inputs/module-warnings/1.o %t.dir
+# RUN: cp %p/../Inputs/module-warnings/Foo.pcm %t.dir/ModuleCache
+#
+# RUN: llvm-dsymutil -f -oso-prepend-path=%t.dir -y \
+# RUN:   %p/dummy-debug-map.map -o %t 2>&1 | FileCheck %s
+#
+# Module-not-found should be reported only once.
+# The exact error message depends on the OS so we don't check for it.
+# CHECK:     warning: {{.*}}Bar.pcm:
+# CHECK-NOT: warning: {{.*}}Bar.pcm:
+#
+# RUN: cp %p/../Inputs/module-warnings/libstatic.a %t.dir
+# RUN: llvm-dsymutil -f -oso-prepend-path=%t.dir -y %s -o %t 2>&1 | FileCheck %s
+# CHECK: rebuild the module cache
+# CHECK-NOT: static libraries
+#
+# RUN: rm -rf %t.dir/ModuleCache
+# RUN: llvm-dsymutil -f -oso-prepend-path=%t.dir -y %s -o %t 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=STATIC
+# STATIC: warning: {{.*}}Bar.pcm:
+# STATIC: note: Linking a static library
+# STATIC: warning: {{.*}}Foo.pcm:
+# STATIC-NOT: note:
+
+---
+triple:          'x86_64-apple-darwin'
+objects:
+  - filename: libstatic.a(1.o)
+    symbols:
+      - { sym: __Z3foov, objAddr: 0x0, binAddr: 0x10000, size: 0x10 }
+...

test/tools/dsymutil/X86/modules-warnings.test

@@ -1,26 +0,0 @@
-# Test for module-related warnings.
-# This reuses the inputs from the modules.m testcase.
-#
-# RUN: rm -rf %t.dir && mkdir %t.dir
-# RUN: cp %p/../Inputs/modules/1.o %p/../Inputs/modules/Foo.pcm %t.dir
-#
-# RUN: llvm-dsymutil -f -oso-prepend-path=%t.dir -y \
-# RUN:   %p/dummy-debug-map.map -o %t 2>&1 | FileCheck %s
-#
-# Module-not-found should be reported only once.
-# The exact error message depends on the OS so we don't check for it.
-# CHECK:     warning: {{.*}}Bar.pcm:
-# CHECK-NOT: warning: {{.*}}Bar.pcm:
-#
-# RUN: cp %p/../Inputs/modules/libstatic.a %t.dir
-# RUN: llvm-dsymutil -f -oso-prepend-path=%t.dir -y %s -o %t 2>&1 | FileCheck %s
-# CHECK: rebuild the module cache
-# CHECK-NOT: static libraries
-
----
-triple:          'x86_64-apple-darwin'
-objects:
-  - filename: libstatic.a(1.o)
-    symbols:
-      - { sym: __Z3foov, objAddr: 0x0, binAddr: 0x10000, size: 0x10 }
-...

tools/dsymutil/DwarfLinker.cpp

@@ -3302,7 +3302,6 @@ void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
     bool isClangModule = sys::path::extension(Filename).equals(".pcm");
     bool isArchive = ObjFile.endswith(")");
     if (isClangModule) {
-      sys::path::remove_filename(Path);
       StringRef ModuleCacheDir = sys::path::parent_path(Path);
       if (sys::fs::exists(ModuleCacheDir)) {
         // If the module's parent directory exists, we assume that the module
@@ -3320,8 +3319,11 @@ void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
         // was built on a different machine. We don't want to discourage module
         // debugging for convenience libraries within a project though.
         if (!ArchiveHintDisplayed) {
-          errs() << "note: Module debugging should be disabled when shipping "
-                    "static libraries.\n";
+          errs() << "note: Linking a static library that was built with "
+                    "-gmodules, but the module cache was not found.  "
+                    "Redistributable static libraries should never be built "
+                    "with module debugging enabled.  The debug experience will "
+                    "be degraded due to incomplete debug information.\n";
           ArchiveHintDisplayed = true;
         }
       }