fix: scoverage statement's line number should be 1-base (#18932)

fix #18916

This PR makes scoverage statements' line number 1-base, instead of
0-base. FYI @tarao

It would be ideal if we could find specifications of many of coverage
report fomats (such as Jacoco XML, cobertura.xml, lcov.txt...) and
confirm most of them expect the line numbers 1-base.

However, it seems there's no formal specification for them AFAIK. Since
we've been using 1-base so far in Scala2 and it hasn't been a problem,
so I guess it's OK to change to 1-base (and most of coverage report
format and visualizer expect 1-base probably).

I believe we should make coverage report 1-base by default, and it
should be reporter / aggregator's responsibility to adjust the line
numbers if some coverage format expects 0-base.

---

I tested on https://github.com/scoverage/sbt-scoverage-samples with HTML
reporter

## 3.3.1

![Screenshot 2023-11-15 at 16 55
06](https://github.com/lampepfl/dotty/assets/9353584/909b7eeb-22ca-41ca-bdfb-dc1e3ceb8ebb)

![Screenshot 2023-11-15 at 16 55
11](https://github.com/lampepfl/dotty/assets/9353584/97f086e2-f597-40e8-bee0-7a5d2dac9294)

In the latter picture, they are "3" even though the actual line number
is 4, because

- scoverage deserializer parses `scoverage.coverage`'s line number as it
is
-
https://github.com/scoverage/scalac-scoverage-plugin/blob/dd519767c916293f6d200639641a7f029970e261/serializer/src/main/scala/scoverage/serialize/Serializer.scala#L147
- and StatementWriter uses the `line` number without adjustment (to
1-base)
-
https://github.com/scoverage/scalac-scoverage-plugin/blob/dd519767c916293f6d200639641a7f029970e261/reporter/src/main/scala/scoverage/reporter/StatementWriter.scala#L34-L36

## 3.4.0-RC1-bin-SNAPSHOT
![Screenshot 2023-11-15 at 17 41
06](https://github.com/lampepfl/dotty/assets/9353584/6cbcaebd-3fae-4fcb-ae22-fc4bd844563a)

seems ok 👍

![Screenshot 2023-11-15 at 17 41
01](https://github.com/lampepfl/dotty/assets/9353584/ca16653f-267c-4e43-962c-abdbf277f30f)

compiler/src/dotty/tools/dotc/coverage/Coverage.scala

@@ -11,7 +11,12 @@ class Coverage:
 
   def addStatement(stmt: Statement): Unit = statementsById(stmt.id) = stmt
 
-/** A statement that can be invoked, and thus counted as "covered" by code coverage tools. */
+
+/**
+  * A statement that can be invoked, and thus counted as "covered" by code coverage tools.
+  *
+  * @param line 1-indexed line number
+  */
 case class Statement(
     location: Location,
     id: Int,

compiler/src/dotty/tools/dotc/transform/InstrumentCoverage.scala

@@ -97,7 +97,9 @@ class InstrumentCoverage extends MacroTransform with IdentityDenotTransformer:
         id = id,
         start = pos.start,
         end = pos.end,
-        line = pos.line,
+        // +1 to account for the line number starting at 1
+        // the internal line number is 0-base https://github.com/lampepfl/dotty/blob/18ada516a85532524a39a962b2ddecb243c65376/compiler/src/dotty/tools/dotc/util/SourceFile.scala#L173-L176
+        line = pos.line + 1,
         desc = sourceFile.content.slice(pos.start, pos.end).mkString,
         symbolName = tree.symbol.name.toSimpleName.toString,
         treeName = tree.getClass.getSimpleName.nn,

tests/coverage/pos/Constructor.scoverage.check

@@ -27,7 +27,7 @@ covtest.C
 <init>
 28
 36
-3
+4
 <init>
 DefDef
 false
@@ -44,7 +44,7 @@ covtest.C
 <init>
 69
 72
-5
+6
 g
 Apply
 false
@@ -61,7 +61,7 @@ covtest.C
 <init>
 80
 88
-8
+9
 <init>
 DefDef
 false
@@ -78,7 +78,7 @@ covtest.C
 <init>
 108
 128
-9
+10
 +
 Apply
 false
@@ -95,7 +95,7 @@ covtest.C
 f
 133
 138
-11
+12
 f
 DefDef
 false
@@ -112,7 +112,7 @@ covtest.C
 x
 153
 158
-12
+13
 x
 DefDef
 false
@@ -129,7 +129,7 @@ covtest.C
 <init>
 165
 169
-13
+14
 f
 Apply
 false
@@ -146,7 +146,7 @@ covtest.C
 <init>
 167
 168
-13
+14
 x
 Select
 false
@@ -163,7 +163,7 @@ covtest.C
 g
 173
 178
-15
+16
 g
 DefDef
 false
@@ -180,7 +180,7 @@ covtest.O$
 g
 203
 208
-18
+19
 g
 DefDef
 false
@@ -197,7 +197,7 @@ covtest.O$
 y
 223
 228
-19
+20
 y
 DefDef
 false
@@ -214,7 +214,7 @@ covtest.O$
 <init>
 235
 239
-20
+21
 g
 Apply
 false
@@ -231,7 +231,7 @@ covtest.O$
 <init>
 237
 238
-20
+21
 y
 Ident
 false

tests/coverage/pos/ContextFunctions.scoverage.check

@@ -27,7 +27,7 @@ covtest.OnError
 onError
 56
 67
-3
+4
 onError
 DefDef
 false
@@ -44,7 +44,7 @@ covtest.Imperative
 readName2
 121
 134
-7
+8
 readName2
 DefDef
 false
@@ -61,7 +61,7 @@ covtest.Imperative
 readPerson
 252
 309
-13
+14
 onError
 Apply
 false
@@ -78,7 +78,7 @@ covtest.Imperative
 readPerson
 252
 295
-13
+14
 <init>
 Apply
 false
@@ -95,7 +95,7 @@ covtest.Imperative
 $anonfun
 267
 294
-13
+14
 apply
 Apply
 false
@@ -112,7 +112,7 @@ covtest.Imperative
 readPerson
 192
 206
-11
+12
 readPerson
 DefDef
 false

tests/coverage/pos/Enum.scoverage.check

@@ -27,7 +27,7 @@ covtest.Planet
 surfaceGravity
 338
 356
-14
+15
 surfaceGravity
 DefDef
 false
@@ -44,7 +44,7 @@ covtest.Planet
 surfaceWeight
 444
 458
-15
+16
 surfaceGravity
 Select
 false
@@ -61,7 +61,7 @@ covtest.Planet
 surfaceWeight
 392
 409
-15
+16
 surfaceWeight
 DefDef
 false
@@ -78,7 +78,7 @@ covtest.EnumTypes$
 test
 1043
 1077
-30
+31
 println
 Apply
 false
@@ -95,7 +95,7 @@ covtest.EnumTypes$
 test
 1051
 1076
-30
+31
 +
 Apply
 false
@@ -112,7 +112,7 @@ covtest.EnumTypes$
 test
 1082
 1103
-31
+32
 println
 Apply
 false
@@ -129,7 +129,7 @@ covtest.EnumTypes$
 test
 1090
 1102
-31
+32
 s
 Apply
 false
@@ -146,7 +146,7 @@ covtest.EnumTypes$
 calculateEarthWeightOnPlanets
 1195
 1222
-34
+35
 surfaceGravity
 Select
 false
@@ -163,7 +163,7 @@ covtest.EnumTypes$
 calculateEarthWeightOnPlanets
 1229
 1320
-35
+36
 foreach
 Apply
 false
@@ -180,7 +180,7 @@ covtest.EnumTypes$
 calculateEarthWeightOnPlanets
 1238
 1251
-35
+36
 refArrayOps
 Apply
 false
@@ -197,7 +197,7 @@ covtest.EnumTypes$
 $anonfun
 1263
 1320
-36
+37
 println
 Apply
 false
@@ -214,7 +214,7 @@ covtest.EnumTypes$
 $anonfun
 1271
 1319
-36
+37
 s
 Apply
 false
@@ -231,7 +231,7 @@ covtest.EnumTypes$
 $anonfun
 1296
 1317
-36
+37
 surfaceWeight
 Apply
 false
@@ -248,7 +248,7 @@ covtest.EnumTypes$
 calculateEarthWeightOnPlanets
 1109
 1142
-33
+34
 calculateEarthWeightOnPlanets
 DefDef
 false
@@ -265,7 +265,7 @@ covtest.EnumTypes$
 test
 1326
 1347
-38
+39
 println
 Apply
 false
@@ -282,7 +282,7 @@ covtest.EnumTypes$
 test
 1352
 1385
-39
+40
 calculateEarthWeightOnPlanets
 Apply
 false
@@ -299,7 +299,7 @@ covtest.EnumTypes$
 test
 901
 909
-27
+28
 test
 DefDef
 false

tests/coverage/pos/Escaping.scoverage.check

@@ -27,7 +27,7 @@ covtest.\n.\r\n\f
 \r\n\f
 69
 80
-3
+4
 length
 Apply
 false
@@ -44,7 +44,7 @@ covtest.\n.\r\n\f
 \r\n\f
 40
 48
-3
+4
 \r\n\f
 DefDef
 false