Feature Enhancement: per-file coverage in Explorer, C/C++ Support & visualize branch/region execution

@types/lcov-parse/index.d.ts

@@ -10,7 +10,9 @@ declare namespace parse {
         block: number,
         branch: number,
         line: number,
-        taken: number
+        taken: number,
+        condition_coverage?: number,  // percentage of condition branches taken (0-100)
+        missing_branches?: number[]   // line numbers of untaken branches
     }
 
     interface FunctionDetail {

README.md

@@ -17,6 +17,9 @@ https://github.com/ryanluker/vscode-coverage-gutters/issues
 ![Coverage Gutters features watch](promo_images/coverage-gutters-features-1.gif)
 
 - Supports any language as long as you can generate a lcov style coverage file
+- **[NEW] Support for C/C++/Rust coverage formats**: Cobertura XML (gcovr) and LLVM-cov JSON
+- **[NEW] Branch coverage details**: CodeLens display and hover tooltips showing branch execution + missing branches
+- **[NEW] LLVM region counts**: Hover shows per-line region execution counts from LLVM JSON exports
 - Extensive logging and insight into operations via the output logs
 - Multi coverage file support for both xml and lcov
 - Coverage caching layer makes for speedy rendering even in large files
@@ -48,6 +51,9 @@ See [examples directory](example) on how to setup a project.
 - [Nodejs](example/node)
 - [Ruby](example/ruby)
 - [DotNet](example/dotnet)
+- [C](example/c) **(NEW)** - Cobertura XML via gcovr
+- [C++](example/cpp) **(NEW)** - Cobertura XML (gcovr) & LLVM-cov JSON
+- [Rust](example/rust) **(NEW)** - LLVM-cov JSON via cargo-tarpaulin or cargo-llvm-cov
 
 ## Tips and Tricks
 **Using Breakpoints**: Currently to both use the extension and code debugging breakpoints, you need to disable the gutter coverage and enable the line coverage via the settings ( `coverage-gutters.showGutterCoverage` and `coverage-gutters.showLineCoverage` respectively).

esbuild.mjs

@@ -0,0 +1,56 @@
+import esbuild from 'esbuild';
+
+const production = process.argv.includes('--production');
+const watch = process.argv.includes('--watch');
+
+async function main() {
+  const ctx = await esbuild.context({
+    entryPoints: ['src/extension.ts'],
+    bundle: true,
+    format: 'cjs',
+    minify: production,
+    sourcemap: !production,
+    sourcesContent: false,
+    platform: 'node',
+    outfile: 'dist/extension.js',
+    external: ['vscode'],
+    logLevel: 'silent',
+    plugins: [
+      /* add to the end of plugins array */
+      esbuildProblemMatcherPlugin
+    ]
+  });
+  if (watch) {
+    await ctx.watch();
+  } else {
+    await ctx.rebuild();
+    await ctx.dispose();
+  }
+}
+
+/**
+ * @type {import('esbuild').Plugin}
+ */
+const esbuildProblemMatcherPlugin = {
+  name: 'esbuild-problem-matcher',
+
+  setup(build) {
+    build.onStart(() => {
+      console.log('[watch] build started');
+    });
+    build.onEnd(result => {
+      result.errors.forEach(({ text, location }) => {
+        console.error(`✘ [ERROR] ${text}`);
+        console.error(`    ${location.file}:${location.line}:${location.column}:`);
+      });
+      console.log('[watch] build finished');
+    });
+  }
+};
+
+main().catch(e => {
+  console.error(e);
+  process.exit(1);
+});
+
+export {};

example/c/README.md

@@ -0,0 +1,68 @@
+# C Coverage Example (single-file)
+
+This example demonstrates generating Cobertura XML coverage (`coverage.xml`) for a C program using GCC and `gcovr`. The code in `src/main.c` intentionally contains multi-conditional `if` logic to demonstrate partial and full coverage.
+
+## Toolchain
+
+Install GCC and gcovr on your machine:
+
+- Debian/Ubuntu
+```bash
+sudo apt-get update
+sudo apt-get install -y gcc gcovr
+```
+
+- macOS (Homebrew)
+```bash
+brew install gcc gcovr
+```
+
+Verify:
+```bash
+gcovr --version
+gcc --version
+```
+
+## Generate Coverage (Cobertura XML)
+
+From this folder (example/c):
+```bash
+# 1) Clean artifacts
+rm -rf build && mkdir -p build
+
+# 2) Build with GCC and gcov instrumentation
+gcc -O0 -g -std=c11 -fprofile-arcs -ftest-coverage -c src/main.c -o build/main.o
+gcc -fprofile-arcs -ftest-coverage -o build/app build/main.o
+
+# 3) Run program to produce .gcda
+./build/app
+
+# 4) Generate Cobertura XML using gcovr
+gcovr \
+    --root . \
+    --object-directory build \
+    --xml -o build/coverage.xml
+
+# (Optional) HTML report
+gcovr --root . --object-directory build --html-details -o build/coverage.html
+```
+
+The Coverage Gutters extension will automatically discover `coverage.xml` (Cobertura format).
+
+## View in VS Code
+
+```bash
+code ../../example.code-workspace
+```
+
+- Open `src/main.c`
+- Run command: Coverage Gutters: Watch Coverage and Visible Editors
+- Decorations appear (green/yellow/red), hovers show details
+
+## Expected Coverage Display
+
+After generating `build/coverage.xml` and opening in VS Code:
+
+- **Green indicators** (✓ Fully covered): fully covered lines/branches
+- **Yellow indicators** (⚠ Partial coverage): lines with partial branch coverage
+- **Red indicators** (✗ Not covered): lines or branches not executed

example/c/coverage.xml

@@ -0,0 +1,3 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<!DOCTYPE coverage SYSTEM 'http://cobertura.sourceforge.net/xml/coverage-04.dtd'>
+<coverage line-rate="0.8636363636363636" branch-rate="0.5268817204301075" lines-covered="76" lines-valid="88" branches-covered="98" branches-valid="186" complexity="0.0" timestamp="1766158321" version="gcovr 4.2"><sources><source>.</source></sources><packages><package name="src" line-rate="0.8636363636363636" branch-rate="0.5268817204301075" complexity="0.0"><classes><class name="main_c" filename="src/main.c" line-rate="0.8636363636363636" branch-rate="0.5268817204301075" complexity="0.0"><methods/><lines><line number="8" hits="3" branch="false"/><line number="9" hits="3" branch="false"/><line number="11" hits="3" branch="true" condition-coverage="50% (3/6)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="12" hits="0" branch="false"/><line number="15" hits="3" branch="true" condition-coverage="50% (4/8)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="16" hits="2" branch="false"/><line number="17" hits="1" branch="true" condition-coverage="12% (1/8)"><conditions><condition number="0" type="jump" coverage="12%"/></conditions></line><line number="18" hits="0" branch="false"/><line number="20" hits="1" branch="false"/><line number="23" hits="3" branch="true" condition-coverage="50% (4/8)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="24" hits="0" branch="false"/><line number="25" hits="3" branch="true" condition-coverage="75% (3/4)"><conditions><condition number="0" type="jump" coverage="75%"/></conditions></line><line number="26" hits="1" branch="false"/><line number="27" hits="2" branch="true" condition-coverage="75% (3/4)"><conditions><condition number="0" type="jump" coverage="75%"/></conditions></line><line number="28" hits="1" branch="false"/><line number="32" hits="3" branch="true" condition-coverage="50% (5/10)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="33" hits="1" branch="false"/><line number="36" hits="3" branch="false"/><line number="40" hits="3" branch="false"/><line number="42" hits="3" branch="true" condition-coverage="50% (3/6)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="43" hits="0" branch="false"/><line number="46" hits="3" branch="true" condition-coverage="62% (5/8)"><conditions><condition number="0" type="jump" coverage="62%"/></conditions></line><line number="47" hits="0" branch="true" condition-coverage="0% (0/4)"><conditions><condition number="0" type="jump" coverage="0%"/></conditions></line><line number="48" hits="1" branch="false"/><line number="51" hits="2" branch="true" condition-coverage="70% (7/10)"><conditions><condition number="0" type="jump" coverage="70%"/></conditions></line><line number="52" hits="1" branch="true" condition-coverage="50% (2/4)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="53" hits="1" branch="false"/><line number="56" hits="1" branch="true" condition-coverage="33% (2/6)"><conditions><condition number="0" type="jump" coverage="33%"/></conditions></line><line number="57" hits="1" branch="false"/><line number="60" hits="0" branch="false"/><line number="65" hits="3" branch="false"/><line number="66" hits="3" branch="false"/><line number="67" hits="3" branch="false"/><line number="68" hits="3" branch="false"/><line number="69" hits="3" branch="false"/><line number="71" hits="3" branch="true" condition-coverage="50% (1/2)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="72" hits="0" branch="false"/><line number="75" hits="3" branch="true" condition-coverage="66% (4/6)"><conditions><condition number="0" type="jump" coverage="66%"/></conditions></line><line number="76" hits="1" branch="false"/><line number="79" hits="2" branch="true" condition-coverage="25% (2/8)"><conditions><condition number="0" type="jump" coverage="25%"/></conditions></line><line number="80" hits="0" branch="false"/><line number="83" hits="2" branch="true" condition-coverage="16% (1/6)"><conditions><condition number="0" type="jump" coverage="16%"/></conditions></line><line number="84" hits="0" branch="false"/><line number="87" hits="2" branch="false"/><line number="91" hits="3" branch="false"/><line number="92" hits="3" branch="true" condition-coverage="50% (2/4)"><conditions><condition number="0" type="jump" coverage="50%"/></conditions></line><line number="94" hits="3" branch="false"/><line number="95" hits="23" branch="true" condition-coverage="100% (2/2)"><conditions><condition number="0" type="jump" coverage="100%"/></conditions></line><line number="96" hits="20" branch="false"/><line number="97" hits="20" branch="true" condition-coverage="100% (4/4)"><conditions><condition number="0" type="jump" coverage="100%"/></conditions></line><line number="98" hits="18" branch="true" condition-coverage="100% (4/4)"><conditions><condition number="0" type="jump" coverage="100%"/></conditions></line><line number="99" hits="18" branch="true" condition-coverage="100% (10/10)"><conditions><condition number="0" type="jump" coverage="100%"/></conditions></line><line number="100" hits="10" branch="true" condition-coverage="75% (3/4)"><conditions><condition number="0" type="jump" coverage="75%"/></conditions></line><line number="101" hits="1" branch="false"/><line number="104" hits="3" branch="false"/><line number="105" hits="3" branch="true" condition-coverage="75% (6/8)"><conditions><condition number="0" type="jump" coverage="75%"/></conditions></line><line number="106" hits="3" branch="true" condition-coverage="33% (2/6)"><conditions><condition number="0" type="jump" coverage="33%"/></conditions></line><line number="107" hits="3" branch="false"/><line number="111" hits="3" branch="false"/><line number="112" hits="3" branch="false"/><line number="113" hits="3" branch="true" condition-coverage="58% (7/12)"><conditions><condition number="0" type="jump" coverage="58%"/></conditions></line><line number="115" hits="2" branch="false"/><line number="116" hits="1" branch="true" condition-coverage="33% (2/6)"><conditions><condition number="0" type="jump" coverage="33%"/></conditions></line><line number="117" hits="1" branch="false"/><line number="118" hits="0" branch="true" condition-coverage="0% (0/10)"><conditions><condition number="0" type="jump" coverage="0%"/></conditions></line><line number="119" hits="0" branch="false"/><line number="121" hits="0" branch="false"/><line number="124" hits="3" branch="true" condition-coverage="75% (6/8)"><conditions><condition number="0" type="jump" coverage="75%"/></conditions></line><line number="125" hits="1" branch="false"/><line number="127" hits="3" branch="false"/><line number="130" hits="1" branch="false"/><line number="131" hits="1" branch="false"/><line number="134" hits="1" branch="false"/><line number="135" hits="1" branch="false"/><line number="136" hits="1" branch="false"/><line number="138" hits="1" branch="false"/><line number="139" hits="1" branch="false"/><line number="140" hits="1" branch="false"/><line number="142" hits="1" branch="false"/><line number="143" hits="1" branch="false"/><line number="144" hits="1" branch="false"/><line number="146" hits="1" branch="false"/><line number="147" hits="1" branch="false"/><line number="148" hits="1" branch="false"/><line number="150" hits="1" branch="false"/><line number="151" hits="1" branch="false"/><line number="152" hits="1" branch="false"/><line number="154" hits="1" branch="false"/></lines></class></classes></package></packages></coverage>

example/c/src/main.c

@@ -0,0 +1,155 @@
+// C example with multi-conditional branches in a single file
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+// Compute a score with layered conditions and short-circuit logic
+int score_user(int age, int yearsActive, int posts, bool verified) {
+    int score = 0;
+
+    if (age < 0 || yearsActive < 0 || posts < 0) {
+        return -1; // invalid
+    }
+
+    if ((age >= 18 && verified) || (yearsActive > 5 && posts > 100)) {
+        score += 25;
+    } else if ((age >= 16 && yearsActive >= 1) && (verified || posts > 10)) {
+        score += 10;
+    } else {
+        score += 1;
+    }
+
+    if ((posts > 500 && yearsActive > 3) || (verified && posts > 250)) {
+        score += 50;
+    } else if (posts > 50 && yearsActive > 1) {
+        score += 15;
+    } else if (posts == 0 && !verified) {
+        score -= 5;
+    }
+
+    // tiering bonus
+    if ((age > 30 && yearsActive > 10 && verified) || (age > 50 && posts > 50)) {
+        score += 10;
+    }
+
+    return score;
+}
+
+// Categorize risk with nested combinations
+const char* risk_category(int creditScore, int latePayments, double debtRatio,
+                          bool isStudent, bool hasJob) {
+    if (creditScore < 0 || creditScore > 850 || debtRatio < 0.0) {
+        return "invalid";
+    }
+
+    if ((creditScore >= 750 && latePayments == 0 && debtRatio < 0.3) ||
+        (creditScore >= 700 && latePayments <= 1 && debtRatio < 0.25)) {
+        return "low";
+    }
+
+    if ((creditScore >= 650 && latePayments <= 2 && debtRatio < 0.4 && hasJob) ||
+        (isStudent && creditScore >= 620 && debtRatio < 0.35)) {
+        return "medium";
+    }
+
+    if ((creditScore < 600 && latePayments > 2) || debtRatio > 0.6) {
+        return "high";
+    }
+
+    return "unknown";
+}
+
+// Complex boolean decision utilizing flags (bitmask)
+// flags: bit0=require2FA, bit1=admin, bit2=readOnly, bit3=trial
+bool allow_action(int hour24, int failedLogins, int flags, bool emailVerified) {
+    bool require2FA = (flags & 0x1) != 0;
+    bool isAdmin    = (flags & 0x2) != 0;
+    bool readOnly   = (flags & 0x4) != 0;
+    bool trial      = (flags & 0x8) != 0;
+
+    if (readOnly) {
+        return false;
+    }
+
+    if ((hour24 < 6 || hour24 > 22) && !isAdmin) {
+        return false;
+    }
+
+    if ((failedLogins >= 3 && !isAdmin) || (!emailVerified && require2FA)) {
+        return false;
+    }
+
+    if (trial && require2FA && !emailVerified) {
+        return false;
+    }
+
+    return true;
+}
+
+// String utility with mixed conditions
+int word_score(const char* s) {
+    if (s == NULL || s[0] == '\0') return 0;
+
+    int vowels = 0, consonants = 0, digits = 0, others = 0;
+    for (size_t i = 0; s[i] != '\0'; ++i) {
+        char c = s[i];
+        if ((c >= '0' && c <= '9')) { digits++; continue; }
+        char lower = (c >= 'A' && c <= 'Z') ? (char)(c + 32) : c;
+        if (lower=='a'||lower=='e'||lower=='i'||lower=='o'||lower=='u') vowels++;
+        else if (lower >= 'a' && lower <= 'z') consonants++;
+        else others++;
+    }
+
+    int score = vowels*2 + consonants - (digits>0 ? 1:0) - others;
+    if ((vowels >= 3 && consonants >= 3) || (digits >= 2 && others == 0)) score += 5;
+    if ((vowels == 0 && consonants > 5) || (others > 3)) score -= 3;
+    return score;
+}
+
+// Multi-conditional numerical routine
+int bounded_transform(int x, int y, int z) {
+    int res = 0;
+    if ((x > 0 && y > 0 && z > 0) && (x + y > z) && (y + z > x) && (x + z > y)) {
+        // triangle-ish constraints
+        res = x*y + z;
+    } else if ((x <= 0 || y <= 0) && z > 100) {
+        res = z - (x + y);
+    } else if ((x == 0 && y == 0 && z == 0) || (x == y && y == z)) {
+        res = x + y + z;
+    } else {
+        res = x - y + z;
+    }
+
+    if ((res % 2 == 0 && (x & 1) == 1) || (res % 3 == 0 && (y & 1) == 0)) {
+        res += 7;
+    }
+    return res;
+}
+
+int main(void) {
+    printf("Running C coverage example (single-file, complex branches)\n");
+
+    // Exercise multiple code paths but leave some branches uncovered on purpose
+    printf("score_user A: %d\n", score_user(19, 0, 5, true));
+    printf("score_user B: %d\n", score_user(35, 12, 60, true));
+    printf("score_user C: %d\n", score_user(15, 0, 0, false));
+
+    printf("risk low: %s\n", risk_category(760, 0, 0.2, false, true));
+    printf("risk med: %s\n", risk_category(655, 2, 0.33, true, false));
+    printf("risk high: %s\n", risk_category(580, 3, 0.7, false, false));
+
+    printf("allow_action 1: %d\n", allow_action(14, 0, 0x0, true));
+    printf("allow_action 2: %d\n", allow_action(23, 4, 0x1, false));
+    printf("allow_action 3: %d\n", allow_action(7, 2, 0x2, true));
+
+    printf("word_score(foo42): %d\n", word_score("foo42"));
+    printf("word_score(STRong!): %d\n", word_score("STRong!"));
+    printf("word_score(vowels): %d\n", word_score("aeiouxyz"));
+
+    printf("bounded_transform A: %d\n", bounded_transform(3,4,5));
+    printf("bounded_transform B: %d\n", bounded_transform(-1,0,150));
+    printf("bounded_transform C: %d\n", bounded_transform(2,2,2));
+
+    return 0;
+}

example/cpp/README.md

@@ -0,0 +1,66 @@
+# C++ Coverage Example (LLVM-cov JSON)
+
+This example demonstrates generating LLVM coverage in JSON format for a C++ program using Clang and LLVM tools. The code in `src/main.cpp` intentionally contains multi-conditional `if` logic to demonstrate partial coverage, branch details, and region-wise execution counts.
+
+## Toolchain
+
+Install Clang and LLVM tools:
+
+**Debian/Ubuntu:**
+```bash
+sudo apt-get update
+sudo apt-get install -y clang llvm
+```
+
+**macOS (Homebrew):**
+```bash
+brew install llvm
+```
+
+**Verify installation:**
+```bash
+clang++ --version
+llvm-cov --version
+llvm-profdata --version
+```
+
+## Generate LLVM Coverage JSON
+
+LLVM's native coverage export format includes **region-wise execution counts** and detailed branch information for fine-grained coverage analysis.
+
+From this folder (example/cpp):
+
+```bash
+# 1) Clean artifacts
+rm -rf build && mkdir -p build
+
+# 2) Build with Clang profile instrumentation
+clang++ -fprofile-instr-generate -fcoverage-mapping -O0 -g -std=c++17 \
+  -c src/main.cpp -o build/main.o
+clang++ -fprofile-instr-generate -o build/app build/main.o
+
+# 3) Run with profiling enabled
+LLVM_PROFILE_FILE=build/default.profraw ./build/app
+
+# 4) Merge profiling data
+llvm-profdata merge -o build/default.profdata build/default.profraw
+
+# 5) Export coverage as JSON
+llvm-cov export -format=json -instr-profile=build/default.profdata \
+  ./build/app > llvm-cov.json
+```
+
+The extension auto-discovers `llvm-cov.json` and displays:
+- **Line coverage** (green/yellow/red decorations)
+- **Branch coverage** with true/false edge counts (CodeLens + hover)
+- **Region-wise execution counts** on hover (column and count per region entry)
+
+## View in VS Code
+
+```bash
+code ../../example.code-workspace
+```
+
+- Open `src/main.cpp`
+- Run command: Coverage Gutters: Watch Coverage and Visible Editors
+- Decorations appear (green/yellow/red), hovers show details