[clang-apply-replacements] No longer deduplucates replacements from the same TU

Summary:
clang-apply-replacements currently deduplicates all diagnostic replacements. However if you get a duplicated replacement from one TU then its expected that it should not be deduplicated. This goes some way to solving [[ https://bugs.llvm.org/show_bug.cgi?id=45150 | export-fixes to yaml adds extra newlines and breaks offsets. ]]

Take this example yaml.
```
---
MainSourceFile:  '/home/nathan/test/test.cpp'
Diagnostics:
  - DiagnosticName:  readability-braces-around-statements
    DiagnosticMessage:
      Message:         statement should be inside braces
      FilePath:        '/home/nathan/test/test.cpp'
      FileOffset:      14
      Replacements:
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          14
          Length:          0
          ReplacementText: ' {'
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          28
          Length:          0
          ReplacementText: '

}'
  - DiagnosticName:  readability-braces-around-statements
    DiagnosticMessage:
      Message:         statement should be inside braces
      FilePath:        '/home/nathan/test/test.cpp'
      FileOffset:      20
      Replacements:
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          20
          Length:          0
          ReplacementText: ' {'
        - FilePath:        '/home/nathan/test/test.cpp'
          Offset:          28
          Length:          0
          ReplacementText: '

}'
...```

The current behaviour is to deduplicate the text insertions at Offset 28 and only apply one of the replacements.
However as both of these replacements came from the same translation unit we can be confident they were both meant to be applied together
The new behaviour won't deduplicate the text insertion and instead insert both of the replacements.
If the duplicate replacement is found inside different translation units (from a header file change perhaps) then they will still be deduplicated as before.

Reviewers: aaron.ballman, gribozavr2, klimek, ymandel

Reviewed By: ymandel

Subscribers: ymandel, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76054

Author: njames93

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

@@ -143,18 +143,26 @@ groupReplacements(const TUReplacements &TUs, const TUDiagnostics &TUDs,
   llvm::DenseMap<const FileEntry *, std::vector<tooling::Replacement>>
       GroupedReplacements;
 
-  // Deduplicate identical replacements in diagnostics.
+  // Deduplicate identical replacements in diagnostics unless they are from the
+  // same TU.
   // FIXME: Find an efficient way to deduplicate on diagnostics level.
-  llvm::DenseMap<const FileEntry *, std::set<tooling::Replacement>>
+  llvm::DenseMap<const FileEntry *,
+                 std::map<tooling::Replacement,
+                          const tooling::TranslationUnitDiagnostics *>>
       DiagReplacements;
 
-  auto AddToGroup = [&](const tooling::Replacement &R, bool FromDiag) {
+  auto AddToGroup = [&](const tooling::Replacement &R,
+                        const tooling::TranslationUnitDiagnostics *SourceTU) {
     // Use the file manager to deduplicate paths. FileEntries are
     // automatically canonicalized.
     if (auto Entry = SM.getFileManager().getFile(R.getFilePath())) {
-      if (FromDiag) {
+      if (SourceTU) {
         auto &Replaces = DiagReplacements[*Entry];
-        if (!Replaces.insert(R).second)
+        auto It = Replaces.find(R);
+        if (It == Replaces.end())
+          Replaces.emplace(R, SourceTU);
+        else if (It->second != SourceTU)
+          // This replacement is a duplicate of one suggested by another TU.
           return;
       }
       GroupedReplacements[*Entry].push_back(R);
@@ -166,14 +174,14 @@ groupReplacements(const TUReplacements &TUs, const TUDiagnostics &TUDs,
 
   for (const auto &TU : TUs)
     for (const tooling::Replacement &R : TU.Replacements)
-      AddToGroup(R, false);
+      AddToGroup(R, nullptr);
 
   for (const auto &TU : TUDs)
     for (const auto &D : TU.Diagnostics)
       if (const auto *ChoosenFix = tooling::selectFirstFix(D)) {
         for (const auto &Fix : *ChoosenFix)
           for (const tooling::Replacement &R : Fix.second)
-            AddToGroup(R, true);
+            AddToGroup(R, &TU);
       }
 
   // Sort replacements per file to keep consistent behavior when

clang-tools-extra/test/clang-apply-replacements/Inputs/identical-in-TU/file1.yaml

@@ -0,0 +1,19 @@
+---
+MainSourceFile:     identical_in_TU.cpp
+Diagnostics:
+  - DiagnosticName: test-identical-insertion
+    DiagnosticMessage:
+      Message: Fix
+      FilePath: $(path)/identical_in_TU.cpp
+      FileOffset: 12
+      Replacements:
+        - FilePath:        $(path)/identical_in_TU.cpp
+          Offset:          12
+          Length:          0
+          ReplacementText: '0'
+        - FilePath:        $(path)/identical_in_TU.cpp
+          Offset:          12
+          Length:          0
+          ReplacementText: '0'
+...
+

clang-tools-extra/test/clang-apply-replacements/Inputs/identical-in-TU/file2.yaml

@@ -0,0 +1,19 @@
+---
+MainSourceFile:     identical-in-TU.cpp
+Diagnostics:
+  - DiagnosticName: test-identical-insertion
+    DiagnosticMessage:
+      Message: Fix
+      FilePath: $(path)/identical-in-TU.cpp
+      FileOffset: 12
+      Replacements:
+        - FilePath:        $(path)/identical-in-TU.cpp
+          Offset:          12
+          Length:          0
+          ReplacementText: '0'
+        - FilePath:        $(path)/identical-in-TU.cpp
+          Offset:          12
+          Length:          0
+          ReplacementText: '0'
+...
+

clang-tools-extra/test/clang-apply-replacements/Inputs/identical-in-TU/identical-in-TU.cpp

@@ -0,0 +1,2 @@
+class MyType {};
+// CHECK: class MyType00 {};

clang-tools-extra/test/clang-apply-replacements/identical-in-TU.cpp

@@ -0,0 +1,11 @@
+// RUN: mkdir -p %T/Inputs/identical-in-TU
+
+// RUN: grep -Ev "// *[A-Z-]+:" %S/Inputs/identical-in-TU/identical-in-TU.cpp > %T/Inputs/identical-in-TU/identical-in-TU.cpp
+// RUN: sed "s#\$(path)#%/T/Inputs/identical-in-TU#" %S/Inputs/identical-in-TU/file1.yaml > %T/Inputs/identical-in-TU/file1.yaml
+// RUN: sed "s#\$(path)#%/T/Inputs/identical-in-TU#" %S/Inputs/identical-in-TU/file2.yaml > %T/Inputs/identical-in-TU/file2.yaml
+// RUN: clang-apply-replacements %T/Inputs/identical-in-TU
+// RUN: FileCheck -input-file=%T/Inputs/identical-in-TU/identical-in-TU.cpp %S/Inputs/identical-in-TU/identical-in-TU.cpp
+
+// Similar to identical test but each yaml file contains the same fix twice. 
+// This check ensures that only the duplicated replacements in a single yaml 
+// file are applied twice. Addresses PR45150.