[PATCH] D75009: [Diagnostic] Improve discoverability of ftabstop for misleading indentation

[Tyker via Phabricator via cfe-commits]

Tyker created this revision.
Tyker added a reviewer: eli.friedman.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Tyker added a comment.

i tried to find a good message but i don't think i succeeded. any suggestions.


This adds an additional note after the misleading warning when the code has a 
mix of tab and space informing about -ftabstop when -ftabstop is used in the 
generation of the warning.


Repository:
  rC Clang

https://reviews.llvm.org/D75009

Files:
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/lib/Parse/ParseStmt.cpp
  clang/test/Parser/warn-misleading-indentation.cpp


Index: clang/test/Parser/warn-misleading-indentation.cpp
===================================================================
--- clang/test/Parser/warn-misleading-indentation.cpp
+++ clang/test/Parser/warn-misleading-indentation.cpp
@@ -234,7 +234,8 @@
  	return 0;
 #if (TAB_SIZE == 1)
 // expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
-// expected-note@-5 {{here}}
+// expected-note@-3 {{there is a mix of tabs spaces; the tab size (-ftabstop=X) is set to 1}}
+// expected-note@-6 {{here}}
 #endif 
 }
 
@@ -256,7 +257,20 @@
       		return 0;
 #if (TAB_SIZE == 8)
 // expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
-// expected-note@-5 {{here}}
+// expected-note@-3 {{there is a mix of tabs spaces; the tab size (-ftabstop=X) is set to 8}}
+// expected-note@-6 {{here}}
+#endif
+}
+
+int a7()
+{
+	if (0)
+		return 1;
+        return 0;
+#if (TAB_SIZE == 4)
+// expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
+// expected-note@-3 {{there is a mix of tabs spaces; the tab size (-ftabstop=X) is set to 4}}
+// expected-note@-6 {{here}}
 #endif
 }
 
Index: clang/lib/Parse/ParseStmt.cpp
===================================================================
--- clang/lib/Parse/ParseStmt.cpp
+++ clang/lib/Parse/ParseStmt.cpp
@@ -1217,11 +1217,12 @@
 
   /// Compute the column number will aligning tabs on TabStop (-ftabstop), this
   /// gives the visual indentation of the SourceLocation.
-  static unsigned getVisualIndentation(SourceManager &SM, SourceLocation Loc) {
+  static unsigned getVisualIndentation(SourceManager &SM, SourceLocation Loc,
+                                       bool& HasTab, bool& HasSpace) {
     unsigned TabStop = SM.getDiagnostics().getDiagnosticOptions().TabStop;
 
     unsigned ColNo = SM.getSpellingColumnNumber(Loc);
-    if (ColNo == 0 || TabStop == 1)
+    if (ColNo == 0)
       return ColNo;
 
     std::pair<FileID, unsigned> FIDAndOffset = SM.getDecomposedLoc(Loc);
@@ -1241,6 +1242,8 @@
     // expanding tabs.
     for (const char *CurPos = EndPos - (ColNo - 1); CurPos != EndPos;
          ++CurPos) {
+      HasTab |= *CurPos == '\t';
+      HasSpace |= *CurPos == ' ';
       if (*CurPos == '\t')
         // Advance visual column to next tabstop.
         VisualColumn += (TabStop - VisualColumn % TabStop);
@@ -1266,9 +1269,12 @@
       P.MisleadingIndentationElseLoc = SourceLocation();
 
     SourceManager &SM = P.getPreprocessor().getSourceManager();
-    unsigned PrevColNum = getVisualIndentation(SM, PrevLoc);
-    unsigned CurColNum = getVisualIndentation(SM, Tok.getLocation());
-    unsigned StmtColNum = getVisualIndentation(SM, StmtLoc);
+    bool HasTab = false;
+    bool HasSpace = false;
+    unsigned PrevColNum = getVisualIndentation(SM, PrevLoc, HasTab, HasSpace);
+    unsigned CurColNum =
+        getVisualIndentation(SM, Tok.getLocation(), HasTab, HasSpace);
+    unsigned StmtColNum = getVisualIndentation(SM, StmtLoc, HasTab, HasSpace);
 
     if (PrevColNum != 0 && CurColNum != 0 && StmtColNum != 0 &&
         ((PrevColNum > StmtColNum && PrevColNum == CurColNum) ||
@@ -1278,6 +1284,10 @@
         (Tok.isNot(tok::identifier) ||
          P.getPreprocessor().LookAhead(0).isNot(tok::colon))) {
       P.Diag(Tok.getLocation(), diag::warn_misleading_indentation) << Kind;
+      if (HasTab && HasSpace)
+        P.Diag(Tok.getLocation(),
+               diag::note_misleading_indentation_tab_space_mix)
+            << SM.getDiagnostics().getDiagnosticOptions().TabStop;
       P.Diag(StmtLoc, diag::note_previous_statement);
     }
   }
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -63,6 +63,8 @@
   InGroup<MisleadingIndentation>, DefaultIgnore;
 def note_previous_statement : Note<
   "previous statement is here">;
+def note_misleading_indentation_tab_space_mix : Note<
+  "there is a mix of tabs spaces; the tab size (-ftabstop=X) is set to %0">;
 
 def ext_thread_before : Extension<"'__thread' before '%0'">;
 def ext_keyword_as_ident : ExtWarn<

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