From 2cebf24c5b16ba66590dd18776f7166419ce14ad Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sat, 31 May 2025 14:47:36 +0300
Subject: [PATCH 01/20] Validate: report error lines

---
 tools/validate/validate.cpp | 37 ++++++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 0a7936b50af..18ea2497793 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -9,6 +9,7 @@
 #include <filesystem>
 #include <format>
 #include <print>
+#include <ranges>
 #include <string>
 #include <string_view>
 #include <type_traits>
@@ -80,11 +81,18 @@ void scan_file(
     size_t tab_characters            = 0;
     size_t trailing_whitespace_lines = 0;
 
+    constexpr size_t max_error_lines_per_file = 8;
+
+    array<size_t, max_error_lines_per_file> overlength_line_numbers{};
+    array<size_t, max_error_lines_per_file> tab_characters_line_numbers{};
+    array<size_t, max_error_lines_per_file> trailing_whitespace_line_numbers{};
+
     unsigned char prev      = '@';
     unsigned char previous2 = '@';
     unsigned char previous3 = '@';
 
     size_t columns = 0;
+    size_t line    = 1;
 
     for (BinaryFile binary_file{filepath}; binary_file.read_next_block(buffer);) {
         for (const auto& ch : buffer) {
@@ -94,13 +102,18 @@ void scan_file(
                 } else {
                     has_cr = true;
                 }
+                ++line;
             } else {
                 if (ch == LF) {
                     has_lf = true;
+                    ++line;
                 }
             }
 
             if (ch == '\t') {
+                if (tab_characters < max_error_lines_per_file) {
+                    tab_characters_line_numbers[disallowed_characters] = line;
+                }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
                 // 0xEF, 0xBB, and 0xBF are the UTF-8 BOM characters.
@@ -112,17 +125,24 @@ void scan_file(
                 ++disallowed_characters;
                 constexpr size_t MaxErrorsForDisallowedCharacters = 10;
                 if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
-                    validation_failure(any_errors, filepath, "file contains disallowed character 0x{:02X}.",
-                        static_cast<unsigned int>(ch));
+                    validation_failure(any_errors, filepath,
+                        "file contains disallowed character 0x{:02X}. error line {}", static_cast<unsigned int>(ch),
+                        line);
                 }
             }
 
             if (ch == CR || ch == LF) {
                 if (prev == ' ' || prev == '\t') {
+                    if (trailing_whitespace_lines < max_error_lines_per_file) {
+                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = line;
+                    }
                     ++trailing_whitespace_lines;
                 }
 
                 if (columns > max_line_length) {
+                    if (overlength_lines < max_error_lines_per_file) {
+                        overlength_line_numbers[overlength_lines] = line;
+                    }
                     ++overlength_lines;
                 }
                 columns = 0;
@@ -164,12 +184,14 @@ void scan_file(
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, "file contains {} tab characters.", tab_characters);
+        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines (up to {}): {}.",
+            tab_characters, max_error_lines_per_file, tab_characters_line_numbers | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {
-        validation_failure(
-            any_errors, filepath, "file contains {} lines with trailing whitespace.", trailing_whitespace_lines);
+        validation_failure(any_errors, filepath,
+            "file contains {} lines with trailing whitespace. Lines (up to {}): {}.", trailing_whitespace_lines,
+            max_error_lines_per_file, trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
     }
 
     if (overlength_lines != 0) {
@@ -188,8 +210,9 @@ void scan_file(
         static_assert(ranges::is_sorted(checked_extensions));
 
         if (ranges::binary_search(checked_extensions, filepath.extension().wstring())) {
-            validation_failure(any_errors, filepath, "file contains {} lines with more than {} columns.",
-                overlength_lines, max_line_length);
+            validation_failure(any_errors, filepath,
+                "file contains {} lines with more than {} columns. Lines (up to {}): {}.", overlength_lines,
+                max_line_length, max_error_lines_per_file, overlength_line_numbers | views::take(overlength_lines));
         }
     }
 }

From 0f3f6f985259925ef4002736060b4f032641d394 Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sat, 31 May 2025 15:57:20 +0300
Subject: [PATCH 02/20] Line and column in the message parameters

---
 tools/validate/validate.cpp | 86 ++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 31 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 18ea2497793..92fd826ed52 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -55,12 +55,32 @@ class BinaryFile {
     FILE* m_file{nullptr};
 };
 
+
+struct line_and_column_type {
+    size_t line;
+    size_t column;
+};
+
+constexpr line_and_column_type unspecified_line_and_column{1, 1};
+
+template <>
+struct std::formatter<line_and_column_type> {
+    constexpr auto parse(std::format_parse_context& ctx) {
+        return ctx.begin();
+    }
+
+    template <typename FormatContext>
+    auto format(const line_and_column_type& lc, FormatContext& ctx) const {
+        return std::format_to(ctx.out(), "{}:{}", lc.line, lc.column);
+    }
+};
+
 template <class... Args>
-void validation_failure(
-    bool& any_errors, const filesystem::path& filepath, format_string<type_identity_t<Args>...> fmt, Args&&... args) {
+void validation_failure(bool& any_errors, const filesystem::path& filepath, format_string<type_identity_t<Args>...> fmt,
+    line_and_column_type line_and_column, Args&&... args) {
     any_errors = true;
-    print(stderr, "##vso[task.logissue type=error;sourcepath={};linenumber=1;columnnumber=1]Validation failed: ",
-        filepath.string());
+    print(stderr, "##vso[task.logissue type=error;sourcepath={};linenumber={};columnnumber={}]Validation failed: ",
+        filepath.string(), line_and_column.line, line_and_column.column);
     println(stderr, fmt, forward<Args>(args)...);
 }
 
@@ -83,9 +103,9 @@ void scan_file(
 
     constexpr size_t max_error_lines_per_file = 8;
 
-    array<size_t, max_error_lines_per_file> overlength_line_numbers{};
-    array<size_t, max_error_lines_per_file> tab_characters_line_numbers{};
-    array<size_t, max_error_lines_per_file> trailing_whitespace_line_numbers{};
+    array<line_and_column_type, max_error_lines_per_file> overlength_line_numbers{};
+    array<line_and_column_type, max_error_lines_per_file> tab_characters_line_numbers{};
+    array<line_and_column_type, max_error_lines_per_file> trailing_whitespace_line_numbers{};
 
     unsigned char prev      = '@';
     unsigned char previous2 = '@';
@@ -112,7 +132,7 @@ void scan_file(
 
             if (ch == '\t') {
                 if (tab_characters < max_error_lines_per_file) {
-                    tab_characters_line_numbers[disallowed_characters] = line;
+                    tab_characters_line_numbers[tab_characters] = {line, columns};
                 }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
@@ -125,23 +145,22 @@ void scan_file(
                 ++disallowed_characters;
                 constexpr size_t MaxErrorsForDisallowedCharacters = 10;
                 if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
-                    validation_failure(any_errors, filepath,
-                        "file contains disallowed character 0x{:02X}. error line {}", static_cast<unsigned int>(ch),
-                        line);
+                    validation_failure(any_errors, filepath, "file contains disallowed character 0x{:02X}.",
+                        {line, columns}, static_cast<unsigned int>(ch));
                 }
             }
 
             if (ch == CR || ch == LF) {
                 if (prev == ' ' || prev == '\t') {
                     if (trailing_whitespace_lines < max_error_lines_per_file) {
-                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = line;
+                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {line, columns};
                     }
                     ++trailing_whitespace_lines;
                 }
 
                 if (columns > max_line_length) {
                     if (overlength_lines < max_error_lines_per_file) {
-                        overlength_line_numbers[overlength_lines] = line;
+                        overlength_line_numbers[overlength_lines] = {line, columns};
                     }
                     ++overlength_lines;
                 }
@@ -158,40 +177,44 @@ void scan_file(
     }
 
     if (has_cr) {
-        validation_failure(any_errors, filepath, "file contains CR line endings (possibly damaged CRLF).");
+        validation_failure(any_errors, filepath, "file contains CR line endings (possibly damaged CRLF).",
+            unspecified_line_and_column);
     } else if (has_lf && has_crlf) {
-        validation_failure(any_errors, filepath, "file contains mixed line endings (both LF and CRLF).");
+        validation_failure(
+            any_errors, filepath, "file contains mixed line endings (both LF and CRLF).", unspecified_line_and_column);
     } else if (has_lf) {
-        validation_failure(any_errors, filepath, "file contains LF line endings.");
+        validation_failure(any_errors, filepath, "file contains LF line endings.", unspecified_line_and_column);
 
         if (prev != LF) {
-            validation_failure(any_errors, filepath, "file doesn't end with a newline.");
+            validation_failure(any_errors, filepath, "file doesn't end with a newline.", unspecified_line_and_column);
         } else if (previous2 == LF) {
-            validation_failure(any_errors, filepath, "file ends with multiple newlines.");
+            validation_failure(any_errors, filepath, "file ends with multiple newlines.", unspecified_line_and_column);
         }
     } else if (has_crlf) {
         if (previous2 != CR || prev != LF) {
-            validation_failure(any_errors, filepath, "file doesn't end with a newline.");
+            validation_failure(any_errors, filepath, "file doesn't end with a newline.", unspecified_line_and_column);
         } else if (previous3 == LF) {
-            validation_failure(any_errors, filepath, "file ends with multiple newlines.");
+            validation_failure(any_errors, filepath, "file ends with multiple newlines.", unspecified_line_and_column);
         }
     } else {
-        validation_failure(any_errors, filepath, "file doesn't contain any newlines.");
+        validation_failure(any_errors, filepath, "file doesn't contain any newlines.", unspecified_line_and_column);
     }
 
     if (has_utf8_bom) {
-        validation_failure(any_errors, filepath, "file contains UTF-8 BOM characters.");
+        validation_failure(any_errors, filepath, "file contains UTF-8 BOM characters.", unspecified_line_and_column);
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines (up to {}): {}.",
-            tab_characters, max_error_lines_per_file, tab_characters_line_numbers | views::take(tab_characters));
+        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines (up to {}):     {}.",
+            tab_characters_line_numbers[0], tab_characters, max_error_lines_per_file,
+            tab_characters_line_numbers | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {
         validation_failure(any_errors, filepath,
-            "file contains {} lines with trailing whitespace. Lines (up to {}): {}.", trailing_whitespace_lines,
-            max_error_lines_per_file, trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
+            "file contains {} lines with trailing whitespace. Lines (up to {}): {}.",
+            trailing_whitespace_line_numbers[0], trailing_whitespace_lines, max_error_lines_per_file,
+            trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
     }
 
     if (overlength_lines != 0) {
@@ -211,8 +234,9 @@ void scan_file(
 
         if (ranges::binary_search(checked_extensions, filepath.extension().wstring())) {
             validation_failure(any_errors, filepath,
-                "file contains {} lines with more than {} columns. Lines (up to {}): {}.", overlength_lines,
-                max_line_length, max_error_lines_per_file, overlength_line_numbers | views::take(overlength_lines));
+                "file contains {} lines with more than {} columns. Lines and columns (up to {}): {}.",
+                overlength_line_numbers[0], overlength_lines, max_line_length, max_error_lines_per_file,
+                overlength_line_numbers | views::take(overlength_lines));
         }
     }
 }
@@ -290,11 +314,11 @@ int main() {
         constexpr size_t maximum_relative_path_length = 120;
         if (relative_path.size() > maximum_relative_path_length) {
             validation_failure(any_errors, filepath, "filepath is too long ({} characters; the limit is {}).",
-                relative_path.size(), maximum_relative_path_length);
+                unspecified_line_and_column, relative_path.size(), maximum_relative_path_length);
         }
 
         if (relative_path.find(L' ') != wstring::npos) {
-            validation_failure(any_errors, filepath, "filepath contains spaces.");
+            validation_failure(any_errors, filepath, "filepath contains spaces.", unspecified_line_and_column);
         }
 
         const wstring extension = filepath.extension().wstring();
@@ -304,7 +328,7 @@ int main() {
         }
 
         if (ranges::binary_search(bad_extensions, extension)) {
-            validation_failure(any_errors, filepath, "file should not be checked in.");
+            validation_failure(any_errors, filepath, "file should not be checked in.", unspecified_line_and_column);
             continue;
         }
 

From 83fda835887d743b3c8a757d1a9b2716a9048d14 Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sat, 31 May 2025 15:59:54 +0300
Subject: [PATCH 03/20] Consistent message

---
 tools/validate/validate.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 92fd826ed52..a271dfd401d 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -205,14 +205,14 @@ void scan_file(
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines (up to {}):     {}.",
+        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines and columns (up to {}): {}.",
             tab_characters_line_numbers[0], tab_characters, max_error_lines_per_file,
             tab_characters_line_numbers | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {
         validation_failure(any_errors, filepath,
-            "file contains {} lines with trailing whitespace. Lines (up to {}): {}.",
+            "file contains {} lines with trailing whitespace. Lines and columns (up to {}): {}.",
             trailing_whitespace_line_numbers[0], trailing_whitespace_lines, max_error_lines_per_file,
             trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
     }

From 28a2e1cc04219b9e40105bf19a2fa3846f08b884 Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sun, 1 Jun 2025 10:48:06 +0300
Subject: [PATCH 04/20] less disruption via overload

---
 tools/validate/validate.cpp | 59 +++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 29 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index a271dfd401d..ba62d0966f6 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -61,8 +61,6 @@ struct line_and_column_type {
     size_t column;
 };
 
-constexpr line_and_column_type unspecified_line_and_column{1, 1};
-
 template <>
 struct std::formatter<line_and_column_type> {
     constexpr auto parse(std::format_parse_context& ctx) {
@@ -76,14 +74,20 @@ struct std::formatter<line_and_column_type> {
 };
 
 template <class... Args>
-void validation_failure(bool& any_errors, const filesystem::path& filepath, format_string<type_identity_t<Args>...> fmt,
-    line_and_column_type line_and_column, Args&&... args) {
+void validation_failure(bool& any_errors, const filesystem::path& filepath, line_and_column_type line_and_column,
+    format_string<type_identity_t<Args>...> fmt, Args&&... args) {
     any_errors = true;
     print(stderr, "##vso[task.logissue type=error;sourcepath={};linenumber={};columnnumber={}]Validation failed: ",
         filepath.string(), line_and_column.line, line_and_column.column);
     println(stderr, fmt, forward<Args>(args)...);
 }
 
+template <class... Args>
+void validation_failure(
+    bool& any_errors, const filesystem::path& filepath, format_string<type_identity_t<Args>...> fmt, Args&&... args) {
+    validation_failure(any_errors, filepath, {1, 1}, fmt, forward<Args>(args)...);
+}
+
 enum class TabPolicy : bool { Forbidden, Allowed };
 
 void scan_file(
@@ -145,8 +149,8 @@ void scan_file(
                 ++disallowed_characters;
                 constexpr size_t MaxErrorsForDisallowedCharacters = 10;
                 if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
-                    validation_failure(any_errors, filepath, "file contains disallowed character 0x{:02X}.",
-                        {line, columns}, static_cast<unsigned int>(ch));
+                    validation_failure(any_errors, filepath, {line, columns},
+                        "file contains disallowed character 0x{:02X}.", static_cast<unsigned int>(ch));
                 }
             }
 
@@ -177,43 +181,41 @@ void scan_file(
     }
 
     if (has_cr) {
-        validation_failure(any_errors, filepath, "file contains CR line endings (possibly damaged CRLF).",
-            unspecified_line_and_column);
+        validation_failure(any_errors, filepath, "file contains CR line endings (possibly damaged CRLF).");
     } else if (has_lf && has_crlf) {
-        validation_failure(
-            any_errors, filepath, "file contains mixed line endings (both LF and CRLF).", unspecified_line_and_column);
+        validation_failure(any_errors, filepath, "file contains mixed line endings (both LF and CRLF).");
     } else if (has_lf) {
-        validation_failure(any_errors, filepath, "file contains LF line endings.", unspecified_line_and_column);
+        validation_failure(any_errors, filepath, "file contains LF line endings.");
 
         if (prev != LF) {
-            validation_failure(any_errors, filepath, "file doesn't end with a newline.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "file doesn't end with a newline.");
         } else if (previous2 == LF) {
-            validation_failure(any_errors, filepath, "file ends with multiple newlines.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "file ends with multiple newlines.");
         }
     } else if (has_crlf) {
         if (previous2 != CR || prev != LF) {
-            validation_failure(any_errors, filepath, "file doesn't end with a newline.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "file doesn't end with a newline.");
         } else if (previous3 == LF) {
-            validation_failure(any_errors, filepath, "file ends with multiple newlines.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "file ends with multiple newlines.");
         }
     } else {
-        validation_failure(any_errors, filepath, "file doesn't contain any newlines.", unspecified_line_and_column);
+        validation_failure(any_errors, filepath, "file doesn't contain any newlines.");
     }
 
     if (has_utf8_bom) {
-        validation_failure(any_errors, filepath, "file contains UTF-8 BOM characters.", unspecified_line_and_column);
+        validation_failure(any_errors, filepath, "file contains UTF-8 BOM characters.");
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, "file contains {} tab characters. Lines and columns (up to {}): {}.",
-            tab_characters_line_numbers[0], tab_characters, max_error_lines_per_file,
-            tab_characters_line_numbers | views::take(tab_characters));
+        validation_failure(any_errors, filepath, tab_characters_line_numbers[0],
+            "file contains {} tab characters. Lines and columns (up to {}): {}.", tab_characters,
+            max_error_lines_per_file, tab_characters_line_numbers | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {
-        validation_failure(any_errors, filepath,
+        validation_failure(any_errors, filepath, trailing_whitespace_line_numbers[0],
             "file contains {} lines with trailing whitespace. Lines and columns (up to {}): {}.",
-            trailing_whitespace_line_numbers[0], trailing_whitespace_lines, max_error_lines_per_file,
+            trailing_whitespace_lines, max_error_lines_per_file,
             trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
     }
 
@@ -233,10 +235,9 @@ void scan_file(
         static_assert(ranges::is_sorted(checked_extensions));
 
         if (ranges::binary_search(checked_extensions, filepath.extension().wstring())) {
-            validation_failure(any_errors, filepath,
-                "file contains {} lines with more than {} columns. Lines and columns (up to {}): {}.",
-                overlength_line_numbers[0], overlength_lines, max_line_length, max_error_lines_per_file,
-                overlength_line_numbers | views::take(overlength_lines));
+            validation_failure(any_errors, filepath, overlength_line_numbers[0],
+                "file contains {} lines with more than {} columns. Lines and columns (up to {}): {}.", overlength_lines,
+                max_line_length, max_error_lines_per_file, overlength_line_numbers | views::take(overlength_lines));
         }
     }
 }
@@ -314,11 +315,11 @@ int main() {
         constexpr size_t maximum_relative_path_length = 120;
         if (relative_path.size() > maximum_relative_path_length) {
             validation_failure(any_errors, filepath, "filepath is too long ({} characters; the limit is {}).",
-                unspecified_line_and_column, relative_path.size(), maximum_relative_path_length);
+                relative_path.size(), maximum_relative_path_length);
         }
 
         if (relative_path.find(L' ') != wstring::npos) {
-            validation_failure(any_errors, filepath, "filepath contains spaces.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "filepath contains spaces.");
         }
 
         const wstring extension = filepath.extension().wstring();
@@ -328,7 +329,7 @@ int main() {
         }
 
         if (ranges::binary_search(bad_extensions, extension)) {
-            validation_failure(any_errors, filepath, "file should not be checked in.", unspecified_line_and_column);
+            validation_failure(any_errors, filepath, "file should not be checked in.");
             continue;
         }
 

From 4eaf575a40d1cf467f9919816a75125114977ea3 Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sun, 1 Jun 2025 10:54:47 +0300
Subject: [PATCH 05/20] Fix off by one error

---
 tools/validate/validate.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index ba62d0966f6..258543ef1bb 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -136,7 +136,7 @@ void scan_file(
 
             if (ch == '\t') {
                 if (tab_characters < max_error_lines_per_file) {
-                    tab_characters_line_numbers[tab_characters] = {line, columns};
+                    tab_characters_line_numbers[tab_characters] = {line, columns + 1};
                 }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
@@ -157,14 +157,14 @@ void scan_file(
             if (ch == CR || ch == LF) {
                 if (prev == ' ' || prev == '\t') {
                     if (trailing_whitespace_lines < max_error_lines_per_file) {
-                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {line, columns};
+                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {line, columns + 1};
                     }
                     ++trailing_whitespace_lines;
                 }
 
                 if (columns > max_line_length) {
                     if (overlength_lines < max_error_lines_per_file) {
-                        overlength_line_numbers[overlength_lines] = {line, columns};
+                        overlength_line_numbers[overlength_lines] = {line, columns + 1};
                     }
                     ++overlength_lines;
                 }

From c81422255e7c5c1c7f5aac6c25b68f84a404f974 Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sun, 1 Jun 2025 11:02:47 +0300
Subject: [PATCH 06/20] -line

---
 tools/validate/validate.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 258543ef1bb..af895b00795 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -55,7 +55,6 @@ class BinaryFile {
     FILE* m_file{nullptr};
 };
 
-
 struct line_and_column_type {
     size_t line;
     size_t column;

From e4deb7ff8bc9d101c0aad2b5d5fa7ec996d4e87d Mon Sep 17 00:00:00 2001
From: Alex Guteniev <gutenev@gmail.com>
Date: Sun, 1 Jun 2025 11:03:10 +0300
Subject: [PATCH 07/20] off by one here too

---
 tools/validate/validate.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index af895b00795..eadc8705afe 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -148,7 +148,7 @@ void scan_file(
                 ++disallowed_characters;
                 constexpr size_t MaxErrorsForDisallowedCharacters = 10;
                 if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
-                    validation_failure(any_errors, filepath, {line, columns},
+                    validation_failure(any_errors, filepath, {line, columns + 1},
                         "file contains disallowed character 0x{:02X}.", static_cast<unsigned int>(ch));
                 }
             }

From 555697f5b9ac9bcaba7864f996795d2a6a9ae2bb Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:03:10 -0700
Subject: [PATCH 08/20] Avoid `std::` qualification.

---
 tools/validate/validate.cpp | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index eadc8705afe..62040d9a7ae 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -60,17 +60,19 @@ struct line_and_column_type {
     size_t column;
 };
 
-template <>
-struct std::formatter<line_and_column_type> {
-    constexpr auto parse(std::format_parse_context& ctx) {
-        return ctx.begin();
-    }
+namespace std {
+    template <>
+    struct formatter<line_and_column_type> {
+        constexpr auto parse(format_parse_context& ctx) {
+            return ctx.begin();
+        }
 
-    template <typename FormatContext>
-    auto format(const line_and_column_type& lc, FormatContext& ctx) const {
-        return std::format_to(ctx.out(), "{}:{}", lc.line, lc.column);
-    }
-};
+        template <typename FormatContext>
+        auto format(const line_and_column_type& lc, FormatContext& ctx) const {
+            return format_to(ctx.out(), "{}:{}", lc.line, lc.column);
+        }
+    };
+} // namespace std
 
 template <class... Args>
 void validation_failure(bool& any_errors, const filesystem::path& filepath, line_and_column_type line_and_column,

From ed4bb5e3f8e5c31b872d6d669c6e7ae7b8c8d25a Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:04:50 -0700
Subject: [PATCH 09/20] Consistently take `const line_and_column_type&`.

---
 tools/validate/validate.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 62040d9a7ae..b0ba892b233 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -75,11 +75,11 @@ namespace std {
 } // namespace std
 
 template <class... Args>
-void validation_failure(bool& any_errors, const filesystem::path& filepath, line_and_column_type line_and_column,
+void validation_failure(bool& any_errors, const filesystem::path& filepath, const line_and_column_type& lc,
     format_string<type_identity_t<Args>...> fmt, Args&&... args) {
     any_errors = true;
     print(stderr, "##vso[task.logissue type=error;sourcepath={};linenumber={};columnnumber={}]Validation failed: ",
-        filepath.string(), line_and_column.line, line_and_column.column);
+        filepath.string(), lc.line, lc.column);
     println(stderr, fmt, forward<Args>(args)...);
 }
 

From 0981f3af28a9e059f612a1b54e9a712c3c47edbe Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:09:00 -0700
Subject: [PATCH 10/20] `line_and_column_type` => `line_and_column`

---
 tools/validate/validate.cpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index b0ba892b233..e802fbc5333 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -55,27 +55,27 @@ class BinaryFile {
     FILE* m_file{nullptr};
 };
 
-struct line_and_column_type {
+struct line_and_column {
     size_t line;
     size_t column;
 };
 
 namespace std {
     template <>
-    struct formatter<line_and_column_type> {
+    struct formatter<line_and_column> {
         constexpr auto parse(format_parse_context& ctx) {
             return ctx.begin();
         }
 
         template <typename FormatContext>
-        auto format(const line_and_column_type& lc, FormatContext& ctx) const {
+        auto format(const line_and_column& lc, FormatContext& ctx) const {
             return format_to(ctx.out(), "{}:{}", lc.line, lc.column);
         }
     };
 } // namespace std
 
 template <class... Args>
-void validation_failure(bool& any_errors, const filesystem::path& filepath, const line_and_column_type& lc,
+void validation_failure(bool& any_errors, const filesystem::path& filepath, const line_and_column& lc,
     format_string<type_identity_t<Args>...> fmt, Args&&... args) {
     any_errors = true;
     print(stderr, "##vso[task.logissue type=error;sourcepath={};linenumber={};columnnumber={}]Validation failed: ",
@@ -108,9 +108,9 @@ void scan_file(
 
     constexpr size_t max_error_lines_per_file = 8;
 
-    array<line_and_column_type, max_error_lines_per_file> overlength_line_numbers{};
-    array<line_and_column_type, max_error_lines_per_file> tab_characters_line_numbers{};
-    array<line_and_column_type, max_error_lines_per_file> trailing_whitespace_line_numbers{};
+    array<line_and_column, max_error_lines_per_file> overlength_line_numbers{};
+    array<line_and_column, max_error_lines_per_file> tab_characters_line_numbers{};
+    array<line_and_column, max_error_lines_per_file> trailing_whitespace_line_numbers{};
 
     unsigned char prev      = '@';
     unsigned char previous2 = '@';

From 49956126059aac3c12717ac1a28ec287ca186674 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:14:21 -0700
Subject: [PATCH 11/20] Track 0-based `lines` while reading the file.

---
 tools/validate/validate.cpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index e802fbc5333..d9ee06e05ff 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -117,7 +117,7 @@ void scan_file(
     unsigned char previous3 = '@';
 
     size_t columns = 0;
-    size_t line    = 1;
+    size_t lines   = 0;
 
     for (BinaryFile binary_file{filepath}; binary_file.read_next_block(buffer);) {
         for (const auto& ch : buffer) {
@@ -127,17 +127,17 @@ void scan_file(
                 } else {
                     has_cr = true;
                 }
-                ++line;
+                ++lines;
             } else {
                 if (ch == LF) {
                     has_lf = true;
-                    ++line;
+                    ++lines;
                 }
             }
 
             if (ch == '\t') {
                 if (tab_characters < max_error_lines_per_file) {
-                    tab_characters_line_numbers[tab_characters] = {line, columns + 1};
+                    tab_characters_line_numbers[tab_characters] = {lines + 1, columns + 1};
                 }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
@@ -150,7 +150,7 @@ void scan_file(
                 ++disallowed_characters;
                 constexpr size_t MaxErrorsForDisallowedCharacters = 10;
                 if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
-                    validation_failure(any_errors, filepath, {line, columns + 1},
+                    validation_failure(any_errors, filepath, {lines + 1, columns + 1},
                         "file contains disallowed character 0x{:02X}.", static_cast<unsigned int>(ch));
                 }
             }
@@ -158,14 +158,14 @@ void scan_file(
             if (ch == CR || ch == LF) {
                 if (prev == ' ' || prev == '\t') {
                     if (trailing_whitespace_lines < max_error_lines_per_file) {
-                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {line, columns + 1};
+                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {lines + 1, columns + 1};
                     }
                     ++trailing_whitespace_lines;
                 }
 
                 if (columns > max_line_length) {
                     if (overlength_lines < max_error_lines_per_file) {
-                        overlength_line_numbers[overlength_lines] = {line, columns + 1};
+                        overlength_line_numbers[overlength_lines] = {lines + 1, columns + 1};
                     }
                     ++overlength_lines;
                 }

From af61ed6e8d31d7bc188a2b481cf890336a38896d Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:20:16 -0700
Subject: [PATCH 12/20] `tab_characters_line_numbers` =>
 `tab_character_line_numbers`

---
 tools/validate/validate.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index d9ee06e05ff..f6eb3e0e8a9 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -109,7 +109,7 @@ void scan_file(
     constexpr size_t max_error_lines_per_file = 8;
 
     array<line_and_column, max_error_lines_per_file> overlength_line_numbers{};
-    array<line_and_column, max_error_lines_per_file> tab_characters_line_numbers{};
+    array<line_and_column, max_error_lines_per_file> tab_character_line_numbers{};
     array<line_and_column, max_error_lines_per_file> trailing_whitespace_line_numbers{};
 
     unsigned char prev      = '@';
@@ -137,7 +137,7 @@ void scan_file(
 
             if (ch == '\t') {
                 if (tab_characters < max_error_lines_per_file) {
-                    tab_characters_line_numbers[tab_characters] = {lines + 1, columns + 1};
+                    tab_character_line_numbers[tab_characters] = {lines + 1, columns + 1};
                 }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
@@ -208,9 +208,9 @@ void scan_file(
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, tab_characters_line_numbers[0],
+        validation_failure(any_errors, filepath, tab_character_line_numbers[0],
             "file contains {} tab characters. Lines and columns (up to {}): {}.", tab_characters,
-            max_error_lines_per_file, tab_characters_line_numbers | views::take(tab_characters));
+            max_error_lines_per_file, tab_character_line_numbers | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {

From f675d570cd0ae2f3f4ed728667cb2a4d19528b7f Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:22:20 -0700
Subject: [PATCH 13/20] `typename` => `class`

---
 tools/validate/validate.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index f6eb3e0e8a9..aadc540768c 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -67,7 +67,7 @@ namespace std {
             return ctx.begin();
         }
 
-        template <typename FormatContext>
+        template <class FormatContext>
         auto format(const line_and_column& lc, FormatContext& ctx) const {
             return format_to(ctx.out(), "{}:{}", lc.line, lc.column);
         }

From bc37e18949d5c454f4497f5dccf9f3726283fd76 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 13:25:41 -0700
Subject: [PATCH 14/20] Add DMIs for `line_and_column`.

1 is the "default" / "don't care" value used below.
---
 tools/validate/validate.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index aadc540768c..a986e2aaaa7 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -56,8 +56,8 @@ class BinaryFile {
 };
 
 struct line_and_column {
-    size_t line;
-    size_t column;
+    size_t line   = 1;
+    size_t column = 1;
 };
 
 namespace std {

From be185f5e21265ec4f66a94f7e33755ed529e4b49 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 15:40:18 -0700
Subject: [PATCH 15/20] Consistently mention lines before columns.

---
 tools/validate/validate.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index a986e2aaaa7..9f369bea1ad 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -116,8 +116,8 @@ void scan_file(
     unsigned char previous2 = '@';
     unsigned char previous3 = '@';
 
-    size_t columns = 0;
     size_t lines   = 0;
+    size_t columns = 0;
 
     for (BinaryFile binary_file{filepath}; binary_file.read_next_block(buffer);) {
         for (const auto& ch : buffer) {

From 9a413167538d0f642da44bbf51817bb5fec99f1d Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 15:51:25 -0700
Subject: [PATCH 16/20] Use the new limit/pattern for `disallowed_characters`.

---
 tools/validate/validate.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 9f369bea1ad..159c40ad1f6 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -147,12 +147,11 @@ void scan_file(
             } else if (ch != CR && ch != LF && !(ch >= 0x20 && ch <= 0x7E)) {
                 // [0x20, 0x7E] are the printable characters, including the space character.
                 // https://en.wikipedia.org/wiki/ASCII#Printable_characters
-                ++disallowed_characters;
-                constexpr size_t MaxErrorsForDisallowedCharacters = 10;
-                if (disallowed_characters <= MaxErrorsForDisallowedCharacters) {
+                if (disallowed_characters < max_error_lines_per_file) {
                     validation_failure(any_errors, filepath, {lines + 1, columns + 1},
                         "file contains disallowed character 0x{:02X}.", static_cast<unsigned int>(ch));
                 }
+                ++disallowed_characters;
             }
 
             if (ch == CR || ch == LF) {

From b68d4b3b3e0c54f7b61e4262c4fa03792597a857 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Thu, 5 Jun 2025 15:58:23 -0700
Subject: [PATCH 17/20] Also increment lines when file ends with CR.

---
 tools/validate/validate.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 159c40ad1f6..222f1443e72 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -178,6 +178,7 @@ void scan_file(
 
     if (prev == CR) { // file ends with CR
         has_cr = true;
+        ++lines;
     }
 
     if (has_cr) {

From a37437269a232e29b5c3da8f799fa326d17a9254 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Fri, 6 Jun 2025 08:33:19 -0700
Subject: [PATCH 18/20] meow_line_numbers => meow_locations

---
 tools/validate/validate.cpp | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 222f1443e72..2d16a7446fb 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -108,9 +108,9 @@ void scan_file(
 
     constexpr size_t max_error_lines_per_file = 8;
 
-    array<line_and_column, max_error_lines_per_file> overlength_line_numbers{};
-    array<line_and_column, max_error_lines_per_file> tab_character_line_numbers{};
-    array<line_and_column, max_error_lines_per_file> trailing_whitespace_line_numbers{};
+    array<line_and_column, max_error_lines_per_file> overlength_locations{};
+    array<line_and_column, max_error_lines_per_file> tab_character_locations{};
+    array<line_and_column, max_error_lines_per_file> trailing_whitespace_locations{};
 
     unsigned char prev      = '@';
     unsigned char previous2 = '@';
@@ -137,7 +137,7 @@ void scan_file(
 
             if (ch == '\t') {
                 if (tab_characters < max_error_lines_per_file) {
-                    tab_character_line_numbers[tab_characters] = {lines + 1, columns + 1};
+                    tab_character_locations[tab_characters] = {lines + 1, columns + 1};
                 }
                 ++tab_characters;
             } else if (ch == 0xEF || ch == 0xBB || ch == 0xBF) {
@@ -157,14 +157,14 @@ void scan_file(
             if (ch == CR || ch == LF) {
                 if (prev == ' ' || prev == '\t') {
                     if (trailing_whitespace_lines < max_error_lines_per_file) {
-                        trailing_whitespace_line_numbers[trailing_whitespace_lines] = {lines + 1, columns + 1};
+                        trailing_whitespace_locations[trailing_whitespace_lines] = {lines + 1, columns + 1};
                     }
                     ++trailing_whitespace_lines;
                 }
 
                 if (columns > max_line_length) {
                     if (overlength_lines < max_error_lines_per_file) {
-                        overlength_line_numbers[overlength_lines] = {lines + 1, columns + 1};
+                        overlength_locations[overlength_lines] = {lines + 1, columns + 1};
                     }
                     ++overlength_lines;
                 }
@@ -208,16 +208,16 @@ void scan_file(
     }
 
     if (tab_policy == TabPolicy::Forbidden && tab_characters != 0) {
-        validation_failure(any_errors, filepath, tab_character_line_numbers[0],
+        validation_failure(any_errors, filepath, tab_character_locations[0],
             "file contains {} tab characters. Lines and columns (up to {}): {}.", tab_characters,
-            max_error_lines_per_file, tab_character_line_numbers | views::take(tab_characters));
+            max_error_lines_per_file, tab_character_locations | views::take(tab_characters));
     }
 
     if (trailing_whitespace_lines != 0) {
-        validation_failure(any_errors, filepath, trailing_whitespace_line_numbers[0],
+        validation_failure(any_errors, filepath, trailing_whitespace_locations[0],
             "file contains {} lines with trailing whitespace. Lines and columns (up to {}): {}.",
             trailing_whitespace_lines, max_error_lines_per_file,
-            trailing_whitespace_line_numbers | views::take(trailing_whitespace_lines));
+            trailing_whitespace_locations | views::take(trailing_whitespace_lines));
     }
 
     if (overlength_lines != 0) {
@@ -236,9 +236,9 @@ void scan_file(
         static_assert(ranges::is_sorted(checked_extensions));
 
         if (ranges::binary_search(checked_extensions, filepath.extension().wstring())) {
-            validation_failure(any_errors, filepath, overlength_line_numbers[0],
+            validation_failure(any_errors, filepath, overlength_locations[0],
                 "file contains {} lines with more than {} columns. Lines and columns (up to {}): {}.", overlength_lines,
-                max_line_length, max_error_lines_per_file, overlength_line_numbers | views::take(overlength_lines));
+                max_line_length, max_error_lines_per_file, overlength_locations | views::take(overlength_lines));
         }
     }
 }

From 3013086a31be161b13acbcc64a841ce990bf1c02 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Fri, 6 Jun 2025 08:51:50 -0700
Subject: [PATCH 19/20] Use the array technique for disallowed characters.

---
 tools/validate/validate.cpp | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 2d16a7446fb..4a0da809fc1 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -60,6 +60,11 @@ struct line_and_column {
     size_t column = 1;
 };
 
+struct character_line_column {
+    unsigned char ch = '?';
+    line_and_column lc;
+};
+
 namespace std {
     template <>
     struct formatter<line_and_column> {
@@ -72,6 +77,18 @@ namespace std {
             return format_to(ctx.out(), "{}:{}", lc.line, lc.column);
         }
     };
+
+    template <>
+    struct formatter<character_line_column> {
+        constexpr auto parse(format_parse_context& ctx) {
+            return ctx.begin();
+        }
+
+        template <class FormatContext>
+        auto format(const character_line_column& clc, FormatContext& ctx) const {
+            return format_to(ctx.out(), "0x{:02X}@{}", static_cast<unsigned int>(clc.ch), clc.lc);
+        }
+    };
 } // namespace std
 
 template <class... Args>
@@ -111,6 +128,7 @@ void scan_file(
     array<line_and_column, max_error_lines_per_file> overlength_locations{};
     array<line_and_column, max_error_lines_per_file> tab_character_locations{};
     array<line_and_column, max_error_lines_per_file> trailing_whitespace_locations{};
+    array<character_line_column, max_error_lines_per_file> disallowed_character_locations{};
 
     unsigned char prev      = '@';
     unsigned char previous2 = '@';
@@ -148,8 +166,7 @@ void scan_file(
                 // [0x20, 0x7E] are the printable characters, including the space character.
                 // https://en.wikipedia.org/wiki/ASCII#Printable_characters
                 if (disallowed_characters < max_error_lines_per_file) {
-                    validation_failure(any_errors, filepath, {lines + 1, columns + 1},
-                        "file contains disallowed character 0x{:02X}.", static_cast<unsigned int>(ch));
+                    disallowed_character_locations[disallowed_characters] = {ch, {lines + 1, columns + 1}};
                 }
                 ++disallowed_characters;
             }
@@ -241,6 +258,12 @@ void scan_file(
                 max_line_length, max_error_lines_per_file, overlength_locations | views::take(overlength_lines));
         }
     }
+
+    if (disallowed_characters != 0) {
+        validation_failure(any_errors, filepath, disallowed_character_locations[0].lc,
+            "file contains {} disallowed characters. Locations (up to {}): {}.", disallowed_characters,
+            max_error_lines_per_file, disallowed_character_locations | views::take(disallowed_characters));
+    }
 }
 
 int main() {

From 4cd3065fd078c73a9284ca34844b59f5346bd081 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@microsoft.com>
Date: Fri, 6 Jun 2025 10:38:00 -0700
Subject: [PATCH 20/20] Spaces. The final frontiers.

---
 tools/validate/validate.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/validate/validate.cpp b/tools/validate/validate.cpp
index 4a0da809fc1..55ed9a2d266 100644
--- a/tools/validate/validate.cpp
+++ b/tools/validate/validate.cpp
@@ -86,7 +86,7 @@ namespace std {
 
         template <class FormatContext>
         auto format(const character_line_column& clc, FormatContext& ctx) const {
-            return format_to(ctx.out(), "0x{:02X}@{}", static_cast<unsigned int>(clc.ch), clc.lc);
+            return format_to(ctx.out(), "0x{:02X} @ {}", static_cast<unsigned int>(clc.ch), clc.lc);
         }
     };
 } // namespace std