From 576f60d80792d85578593039e2b57d6cbb74caa0 Mon Sep 17 00:00:00 2001
From: Graeme Geldenhuys <graemeg@gmail.com>
Date: Wed, 3 Jun 2026 00:40:00 +0100
Subject: [PATCH] fix(stdlib): TStringList.Text/LoadFromFile preserve verbatim
 lines
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SplitIntoList — the sole backend for TStringList.SetText and LoadFromFile —
trimmed leading and trailing spaces from each split segment. That is correct
for CSV-style splitting but wrong for line-splitting: a TStringList must store
each line verbatim, including indentation.

Removed the trimming so each segment is added as Copy(S, Start, Len) untouched.
SplitIntoList has exactly one caller (SetText), so no trimming-dependent code
is affected.

This also fixes a latent test-infrastructure bug: the threaded test runner
parses each subprocess suite's stdout via TStringList.Text and identifies
failure-detail lines by their two-space indentation. With indentation stripped,
those lines never matched, AddFailure was never called, and the merged result
reported zero failures — so the plain summary printed OK even when [Threaded]
suites failed. With lines preserved, the summary now correctly reports failures.

Regression test: TestRun_TextSet_PreservesLeadingWhitespace asserts on raw
stdout so the spaces inside [] are checked without round-tripping through Text.

Self-hosting fixpoint verified clean.
---
 .../test/pascal/cp.test.e2e.tstringlist.pas   | 42 +++++++++++++++++++
 stdlib/src/main/pascal/classes.pas            | 22 ++++------
 2 files changed, 49 insertions(+), 15 deletions(-)

diff --git a/compiler/src/test/pascal/cp.test.e2e.tstringlist.pas b/compiler/src/test/pascal/cp.test.e2e.tstringlist.pas
index 84b9687..4a2ef8e 100644
--- a/compiler/src/test/pascal/cp.test.e2e.tstringlist.pas
+++ b/compiler/src/test/pascal/cp.test.e2e.tstringlist.pas
@@ -39,6 +39,7 @@ type
     procedure TestRun_TextGet;
     procedure TestRun_TextGet_ManyLines;
     procedure TestRun_TextSet;
+    procedure TestRun_TextSet_PreservesLeadingWhitespace;
     procedure TestRun_GrowBeyondInitialCapacity;
     procedure TestRun_Sorted_Add_OrderedOutput;
     procedure TestRun_Sorted_Find;
@@ -278,6 +279,31 @@ const
     end.
     ''';
 
+  { Text/LoadFromFile must preserve each line verbatim, including leading and
+    trailing whitespace — standard TStringList semantics.  Regression for the
+    SplitIntoList trimming bug that silently dropped indentation (which in turn
+    masked failures in the threaded test-runner's subprocess output parser).
+    The program prints each line wrapped in [] so the harness can see the
+    surrounding spaces without itself round-tripping through Text. }
+  SrcTextSetPreservesWhitespace =
+    '''
+    program P;
+    uses Classes;
+    var L: TStringList; I: Integer;
+    begin
+      L := TStringList.Create;
+      L.Text := 'a' + #10 + '  indented' + #10 + 'trailing  ';
+      WriteLn(L.Count);
+      I := 0;
+      while I < L.Count do
+      begin
+        WriteLn('[' + L.Get(I) + ']');
+        I := I + 1
+      end;
+      L.Free
+    end.
+    ''';
+
   SrcGrow =
     '''
     program P;
@@ -694,6 +720,22 @@ begin
   end
 end;
 
+procedure TE2ETStringListTests.TestRun_TextSet_PreservesLeadingWhitespace;
+var
+  Output: string;
+  RCode:  Integer;
+begin
+  if not ToolchainAvailable then begin Fail('<toolchain-missing>'); Exit end;
+  AssertTrue('compile+run',
+    CompileAndRunWithRTL(SrcTextSetPreservesWhitespace, Output, RCode));
+  AssertEquals('exit 0', 0, RCode);
+  { Assert on the raw stdout so the leading/trailing spaces inside [] are
+    checked directly, without round-tripping through Text. }
+  AssertEquals('verbatim lines preserved',
+    '3' + #10 + '[a]' + #10 + '[  indented]' + #10 + '[trailing  ]' + #10,
+    Output);
+end;
+
 procedure TE2ETStringListTests.TestRun_GrowBeyondInitialCapacity;
 var
   Output: string;
diff --git a/stdlib/src/main/pascal/classes.pas b/stdlib/src/main/pascal/classes.pas
index 0d5c2b7..eadfccc 100644
--- a/stdlib/src/main/pascal/classes.pas
+++ b/stdlib/src/main/pascal/classes.pas
@@ -273,9 +273,12 @@ procedure SplitIntoList(const S: string; ASep: Integer; AList: TStringList);
 var
   I:     Integer;
   Start: Integer;
-  SLo:   Integer;
-  SHi:   Integer;
 begin
+  { Line-splitter for TStringList.Text / LoadFromFile.  Each segment between
+    separators is added verbatim — leading and trailing whitespace is part of
+    the line and must be preserved (standard TStringList semantics).  Trimming
+    here previously stripped indentation, which silently corrupted any
+    whitespace-significant text round-tripped through Text. }
   AList.Clear;
   Start := 0;
   I     := 0;
@@ -283,24 +286,13 @@ begin
   begin
     if OrdAt(S, I) = ASep then
     begin
-      { Trim surrounding spaces }
-      SLo := Start;
-      SHi := I - 1;
-      while (SLo <= SHi) and (OrdAt(S, SLo) = 32) do SLo := SLo + 1;
-      while (SHi >= SLo) and (OrdAt(S, SHi) = 32) do SHi := SHi - 1;
-      AList.Add(Copy(S, SLo, SHi - SLo + 1));
+      AList.Add(Copy(S, Start, I - Start));
       Start := I + 1;
     end;
     I := I + 1;
   end;
   if Start < Length(S) then
-  begin
-    SLo := Start;
-    SHi := Length(S) - 1;
-    while (SLo <= SHi) and (OrdAt(S, SLo) = 32) do SLo := SLo + 1;
-    while (SHi >= SLo) and (OrdAt(S, SHi) = 32) do SHi := SHi - 1;
-    AList.Add(Copy(S, SLo, SHi - SLo + 1));
-  end;
+    AList.Add(Copy(S, Start, Length(S) - Start));
 end;