[clang] [clang] Adjust TextDiagnostic style ranges for interesting source region (PR #164941)
Timm Baeder via cfe-commits
cfe-commits at lists.llvm.org
Thu Oct 30 06:34:48 PDT 2025
https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/164941
>From b55b5ee5f3a83dd3a7d6878402b818e0aed11282 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Thu, 30 Oct 2025 14:34:00 +0100
Subject: [PATCH] [clang] Adjust TextDiagnostic style ranges for interesting
source region
---
clang/lib/Frontend/TextDiagnostic.cpp | 74 ++++++++++++++-----
...diags-interesting-source-region-colors.cpp | 28 +++++++
2 files changed, 83 insertions(+), 19 deletions(-)
create mode 100644 clang/test/Frontend/diags-interesting-source-region-colors.cpp
diff --git a/clang/lib/Frontend/TextDiagnostic.cpp b/clang/lib/Frontend/TextDiagnostic.cpp
index aea3e72d92a84..e9d7175ec8a6b 100644
--- a/clang/lib/Frontend/TextDiagnostic.cpp
+++ b/clang/lib/Frontend/TextDiagnostic.cpp
@@ -349,14 +349,13 @@ struct SourceColumnMap {
/// When the source code line we want to print is too long for
/// the terminal, select the "interesting" region.
-static void selectInterestingSourceRegion(std::string &SourceLine,
- std::string &CaretLine,
- std::string &FixItInsertionLine,
- Columns NonGutterColumns,
- const SourceColumnMap &Map) {
- Columns CaretColumns = Columns(CaretLine.size());
- Columns FixItColumns =
- Columns(llvm::sys::locale::columnWidth(FixItInsertionLine));
+static void selectInterestingSourceRegion(
+ std::string &SourceLine, std::string &CaretLine,
+ std::string &FixItInsertionLine, Columns NonGutterColumns,
+ const SourceColumnMap &Map,
+ SmallVector<clang::TextDiagnostic::StyleRange> &Styles) {
+ Columns CaretColumns = CaretLine.size();
+ Columns FixItColumns = llvm::sys::locale::columnWidth(FixItInsertionLine);
Columns MaxColumns =
std::max({Map.columns().V, CaretColumns.V, FixItColumns.V});
// if the number of columns is less than the desired number we're done
@@ -369,13 +368,11 @@ static void selectInterestingSourceRegion(std::string &SourceLine,
// Find the slice that we need to display the full caret line
// correctly.
Columns CaretStart = 0, CaretEnd = CaretLine.size();
- for (; CaretStart != CaretEnd; CaretStart = CaretStart.next())
- if (!isWhitespace(CaretLine[CaretStart.V]))
- break;
+ while (CaretStart != CaretEnd && isWhitespace(CaretLine[CaretStart.V]))
+ CaretStart = CaretStart.next();
- for (; CaretEnd != CaretStart; CaretEnd = CaretEnd.prev())
- if (!isWhitespace(CaretLine[CaretEnd.V - 1]))
- break;
+ while (CaretEnd != CaretStart && isWhitespace(CaretLine[CaretEnd.V]))
+ CaretEnd = CaretEnd.prev();
// caret has already been inserted into CaretLine so the above whitespace
// check is guaranteed to include the caret
@@ -521,8 +518,40 @@ static void selectInterestingSourceRegion(std::string &SourceLine,
if (BackColumnsRemoved > Columns(BackEllipse.size()))
SourceLine.replace(SourceEnd.V, std::string::npos, BackEllipse);
+ // Since we've modified the SourceLine, we also need to adjust the line's
+ // highlighting information. In particular, if we've removed
+ // from the front of the line, we need to move the style ranges to the
+ // left and remove unneeded ranges.
+ Columns FrontDiff = FrontColumnsRemoved > FrontEllipse.size()
+ ? FrontColumnsRemoved - FrontEllipse.size()
+ : 0;
+ Columns CodeStart = FrontColumnsRemoved > FrontEllipse.size()
+ ? FrontEllipse.size()
+ : FrontColumnsRemoved;
+ Bytes CodeEnd = Map.columnToByte(CodeStart + ColumnsKept);
+
+ for (auto &R : Styles) {
+ // Style ranges too far left. Just move them where they don't bother.
+ if (R.End < FrontDiff.V) {
+ R.Start = R.End = std::numeric_limits<int>::max();
+ continue;
+ }
+ // Move them left. (Note that this can wrap R.Start, but that doesn't
+ // matter).
+ R.Start -= FrontDiff.V;
+ R.End -= FrontDiff.V;
+
+ // If the range overlaps the end of the code, don't leak into the back
+ // ellipse.
+ if (R.Start < CodeEnd.V && R.End > CodeEnd.V)
+ R.End = CodeEnd.V;
+ // Don't leak into the ellipse at the end.
+ if (R.Start >= CodeEnd.V)
+ R.Start = R.End = std::numeric_limits<int>::max();
+ }
+
// If that's enough then we're done
- if (FrontColumnsRemoved + ColumnsKept <= Columns(NonGutterColumns))
+ if (FrontColumnsRemoved + ColumnsKept <= NonGutterColumns)
return;
// Otherwise remove the front as well
@@ -1391,6 +1420,12 @@ void TextDiagnostic::emitSnippetAndCaret(
OS.indent(MaxLineNoDisplayWidth + 2) << "| ";
};
+ Columns MessageLength = DiagOpts.MessageLength;
+
+ // If we don't have enough columns available, just abort now.
+ if (MessageLength != 0 && MessageLength <= Columns(MaxLineNoDisplayWidth + 4))
+ return;
+
// Prepare source highlighting information for the lines we're about to
// emit, starting from the first line.
std::unique_ptr<SmallVector<StyleRange>[]> SourceStyles =
@@ -1450,10 +1485,10 @@ void TextDiagnostic::emitSnippetAndCaret(
// If the source line is too long for our terminal, select only the
// "interesting" source region within that line.
- Columns MessageLength = DiagOpts.MessageLength;
- if (MessageLength.V != 0)
+ if (MessageLength != 0)
selectInterestingSourceRegion(SourceLine, CaretLine, FixItInsertionLine,
- MessageLength, SourceColMap);
+ MessageLength, SourceColMap,
+ SourceStyles[LineNo - Lines.first]);
// If we are in -fdiagnostics-print-source-range-info mode, we are trying
// to produce easily machine parsable output. Add a space before the
@@ -1508,8 +1543,9 @@ void TextDiagnostic::emitSnippet(StringRef SourceLine,
// Print the source line one character at a time.
bool PrintReversed = false;
std::optional<llvm::raw_ostream::Colors> CurrentColor;
- size_t I = 0;
+ size_t I = 0; // Bytes.
while (I < SourceLine.size()) {
+ // llvm::errs() << "I: " <<I << '\n';
auto [Str, WasPrintable] =
printableTextForNextCharacter(SourceLine, &I, DiagOpts.TabStop);
diff --git a/clang/test/Frontend/diags-interesting-source-region-colors.cpp b/clang/test/Frontend/diags-interesting-source-region-colors.cpp
new file mode 100644
index 0000000000000..474b450181942
--- /dev/null
+++ b/clang/test/Frontend/diags-interesting-source-region-colors.cpp
@@ -0,0 +1,28 @@
+// RUN: not %clang_cc1 %s -fmessage-length=40 -fcolor-diagnostics -fno-show-source-location -Wunused-value -o - 2>&1 | FileCheck %s
+
+
+int main() {
+ 1 + + if;
+ // CHECK: expected expression
+ // CHECK-NEXT: ...+ [[MAGENTA:.\[0;34m]]if[[RESET:.\[0m]];
+
+
+ a + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1;
+ // CHECK: use of undeclared identifier
+ // CHECK-NEXT: a + [[GREEN:.\[0;32m]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] ...
+
+
+ /*😂😂😂*/ a + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1;
+ // CHECK: use of undeclared identifier
+ // CHECK-NEXT: [[YELLOW:.\[0;33m]]/*😂😂😂*/[[RESET]] a + [[GREEN:.\[0;32m]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] + [[GREEN]]1[[RESET]] ...
+
+
+
+ "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
+ // CHECK: [[GREEN:.\[0;32m]]"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"[[RESET]];
+
+ "😂xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
+ // CHECK: [[GREEN:.\[0;32m]]"😂xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"[[RESET]];
+}
+
+
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