[clang-tidy] clang-apply-replacements: Don't insert null entry

Summary:
[clang-tidy] clang-apply-replacements: Don't insert null entry

Fix crash when running clang-apply-replacements on YML files which
contain an invalid file path. Make sure we never add a nullptr into the
map. The previous code started adding nullptr to the map after the first
warnings via errs() has been emitted.

Backtrace:
```
Starting program:
/home/kfunk/devel/build/llvm/bin/clang-apply-replacements /tmp/tmpIqtp7m
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
Described file '.moc/../../../../../../src/qt5.8/qtremoteobjects/src/remoteobjects/qremoteobjectregistrysource_p.h' doesn't exist. Ignoring...
...

Program received signal SIGSEGV, Segmentation fault.
main (argc=<optimized out>, argv=<optimized out>) at /home/kfunk/devel/src/llvm/tools/clang/tools/extra/clang-apply-replacements/tool/ClangApplyReplacementsMain.cpp:262
(gdb) p FileAndReplacements.first
$1 = (const clang::FileEntry *) 0x0
(gdb)
```

Added tests.

Before patch:

```
******************** TEST 'Clang Tools :: clang-apply-replacements/invalid-files.cpp' FAILED ********************
Script:
--
mkdir -p /home/kfunk/devel/build/llvm/tools/clang/tools/extra/test/clang-apply-replacements/Output/Inputs/invalid-files
clang-apply-replacements /home/kfunk/devel/build/llvm/tools/clang/tools/extra/test/clang-apply-replacements/Output/Inputs/invalid-files
ls -1 /home/kfunk/devel/build/llvm/tools/clang/tools/extra/test/clang-apply-replacements/Output/Inputs/invalid-files | FileCheck /home/kfunk/devel/src/llvm/tools/clang/tools/extra/test/clang-apply-replacements/invalid-files.cpp --check-prefix=YAML
--
Exit Code: 139

Command Output (stderr):
--
Described file 'idonotexist.h' doesn't exist. Ignoring...
/home/kfunk/devel/build/llvm/tools/clang/tools/extra/test/clang-apply-replacements/Output/invalid-files.cpp.script: line 4:  9919 Segmentation fault      clang-apply-replacements /home/kfunk/devel/build/llvm/tools/clang/tools/extra/test/clang-apply-   replacements/Output/Inputs/invalid-files

--
```

After Patch:

```
PASS: Clang Tools :: clang-apply-replacements/invalid-files.cpp (5 of 6)
```

Reviewers: alexfh, yawanng

Reviewed By: alexfh

Subscribers: cfe-commits, klimek, JDevlieghere, xazax.hun

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D35194

llvm-svn: 308974

clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp

@@ -288,13 +288,12 @@ bool mergeAndDeduplicate(const TUReplacements &TUs,
     for (const tooling::Replacement &R : TU.Replacements) {
       // Use the file manager to deduplicate paths. FileEntries are
       // automatically canonicalized.
-      const FileEntry *Entry = SM.getFileManager().getFile(R.getFilePath());
-      if (!Entry && Warned.insert(R.getFilePath()).second) {
-        errs() << "Described file '" << R.getFilePath()
-               << "' doesn't exist. Ignoring...\n";
-        continue;
+      if (const FileEntry *Entry = SM.getFileManager().getFile(R.getFilePath())) {
+        GroupedReplacements[Entry].push_back(R);
+      } else if (Warned.insert(R.getFilePath()).second) {
+          errs() << "Described file '" << R.getFilePath()
+                 << "' doesn't exist. Ignoring...\n";
       }
-      GroupedReplacements[Entry].push_back(R);
     }
   }
 
@@ -314,13 +313,12 @@ bool mergeAndDeduplicate(const TUDiagnostics &TUs,
         for (const tooling::Replacement &R : Fix.second) {
           // Use the file manager to deduplicate paths. FileEntries are
           // automatically canonicalized.
-          const FileEntry *Entry = SM.getFileManager().getFile(R.getFilePath());
-          if (!Entry && Warned.insert(R.getFilePath()).second) {
-            errs() << "Described file '" << R.getFilePath()
-                   << "' doesn't exist. Ignoring...\n";
-            continue;
+          if (const FileEntry *Entry = SM.getFileManager().getFile(R.getFilePath())) {
+            GroupedReplacements[Entry].push_back(R);
+          } else if (Warned.insert(R.getFilePath()).second) {
+              errs() << "Described file '" << R.getFilePath()
+                     << "' doesn't exist. Ignoring...\n";
           }
-          GroupedReplacements[Entry].push_back(R);
         }
       }
     }

clang-tools-extra/test/clang-apply-replacements/Inputs/invalid-files/invalid-files.yaml

@@ -0,0 +1,12 @@
+---
+MainSourceFile:  ''
+Replacements:
+  - FilePath:        idontexist.h
+    Offset:          2669
+    Length:          0
+    ReplacementText: ' override'
+  - FilePath:        idontexist.h
+    Offset:          2669
+    Length:          0
+    ReplacementText: ' override'
+...

clang-tools-extra/test/clang-apply-replacements/invalid-files.cpp

@@ -0,0 +1,5 @@
+// RUN: mkdir -p %T/invalid-files
+// RUN: clang-apply-replacements %T/invalid-files
+//
+// Check that the yaml files are *not* deleted after running clang-apply-replacements without remove-change-desc-files.
+// RUN: ls %T/Inputs/invalid-files/invalid-files.yaml